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Impact of postharvest calcium chloride treatments on decay rate and physicochemical quality properties in strawberry fruit

BMC Plant Biology volume 24, Article number: 1088 (2024) Cite this article

Abstract

Background

Post-harvest losses cause significant product losses in the world, which leads to food waste. Therefore, it is of great importance for people to have access to sufficient amounts of products by increasing the storage period of fruits with applications such as post-harvest calcium chloride (CaCl2). In this study, the effect of calcium chloride (CaCl2) on physical quality parameters and bioactive contents of stored strawberry fruit (Albion cv.) was investigated. Accordingly, strawberries were treated with 2%, 4% and 6% CaCl2 before storage and stored for 15 days (0 ± 0.5 °C and 90 ± 5% RH). Analyses and measurements were conducted every 5 days during the storage period.Weight loss, decay rate, soluble solids content (SSC), acidity, pH, respiration rate, organic acids (malic, citric, ascorbic, fumaric, oxalic, succinic and tartaric) and phenolic compounds (catechin, chlorogenic, ferulic, gallic, o-coumaric, p-coumaric, protocatechuic, quercetin, rutin and syringic) were analyzed as quality parameters during storage.

Results

In the study, in general, the best values were observed in 6% CaCl2-treated fruits in terms of weight loss, SSC, TA, decay and respiration rates, although they varied according to different storage periods. Similarly, in terms of phenolic compounds, organic acids and vitamin C, 6% CaCl2-treated fruits had significantly better prevention of quality losses. In addition, the most common phenolic compound of strawberry fruits was gallic acid, followed by chlorogenic acid and catechin, respectively. On the other hand, the predominant organic acid observed in the fruits was malic acid, followed by citric acid, succinic acid and oxalic acid, respectively.

Conclusions

In this study, it was observed that CaCl2 applications more effectively prevented weight loss and decay rate by reducing the respiration rate compared to the control group at the end of the storage period (15th day). It was concluded that, particularly, the 6% CaCl2 dose can be used as an important treatment to extend storage life by preserving fruit quality and biochemical changes.

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Background

Strawberry, belonging to the genus Fragaria spp. Linnaeus of the Rosaceae family, is a perennial herbaceous plant with superficial roots, with more than twenty species in the world [1]. In well-drained soils, strawberries can grow up to 60–70 cm with fringe-shaped roots and are highly susceptible to adverse environmental conditions, especially suboptimal day length (photoperiod) and temperature factors [2]. The fruit grows in regions of the world with an altitude of at least 1000 m above sea level and in tropical-subtropical climates [3]. Strawberries grow naturally in Turkey, with the highest production in Mersin, Aydın and Muğla provinces, mainly in the Mediterranean and Aegean regions [4]. However, strawberry leaves, which have a lifespan of 1 to 3 months on average and have a dark green color, are arranged spirally in a 2/5 arrangement on the plant stem. The flowers of strawberry consist of five petals and are in the form of panicles [5].

Strawberries are unique among fruits because their seeds are on the outside. They are distinguished by their vibrant red color, juicy texture, and sweet flavor [6]. After adequate pollination, strawberries take approximately 30 to 35 days to ripen. The timing of the harvest varies: strawberries grown outdoors can be picked by mid-March, while those grown under cover are harvested at the end of November [7]. The fruits, which are very delicious with their own aromatic taste, are rich in calcium, phosphorus, potassium, iron, vitamins A, B and C [8]. The rich bioactive compounds (phenolic acids, flavonoids, antioxidants, etc.) present in strawberry fruits are reported to provide certain benefits against various diseases [9]. In addition, the fruit is consumed in large quantities, either directly as fresh fruit for the table or industrially in the form of prepared foods such as jams, juices, pies, ice cream, milkshakes and chocolate [10].

Adverse conditions during cultivation, such as extended transportation, extreme temperature fluctuations, inadequate pre-harvest care, and plant diseases or pests, can significantly shorten the shelf life and storage time of fruits by compromising their quality and freshness [11]. Due to the soft texture of strawberry fruits, their shelf life is short, leading to fruit decay and wastage [12]. Therefore, it is necessary to develop suitable post-harvest processing and storage strategies to preserve the nutritional value and quality of strawberries. To this end, various approaches have been investigated, including edible coatings [13], bioactive coatings [14], modified atmosphere packaging (MAP) [15], UV treatment [16] and calcium chloride [17].

In this method, by applying calcium chloride to the fruit surface after harvest, both the calcium content in the fruit increases and the shelf life of the fruit is significantly extended [18]. Calcium chloride prolongs the shelf life of fruits by preserving their quality and firmness. This inorganic salt is a key component of pectin, which enhances membrane firmness and flexibility in plant cells, thereby maintaining the cell's overall structure and extending the fruit's shelf life [19].

It has been reported that postharvest calcium chloride (2% and 4%) applications preserve the physicochemical properties of strawberry fruits during storage [20]. This study was carried out to determine the effects of calcium chloride applications at doses of 2%, 4% and 6% on some physical and biochemical parameters of strawberry fruits stored for different periods (5, 10 and 15 days). In the study, the effect of calcium chloride on the changes in phenolic compounds and organic acids, which are especially biochemical properties, during storage was investigated.

Material and methods

Material

In this study, fruits were harvested in the application area established with Albion strawberry variety in Bolu (Türkiye) province and these fruits were used in the experiment. Seedlings of Albion strawberry variety were purchased from Yaltır company in Adana (Türkiye) province and the experiment was established with these seedlings. The spacing between Albion strawberry seedlings within the row was 35 cm (Bolu province), and they were irrigated using a drip irrigation system. The strawberry plot, from which the fruits were harvested, was established using Frigo-type seedlings of the Albion cultivar. Strawberry fruits harvested at commercial ripeness with a total soluble solid content (SSC) of 12% were placed in plastic containers and transported to the Bolu Abant İzzet Baysal University Faculty of Agriculture laboratory using a refrigerated vehicle. Calcium chloride doses were adjusted according to the results of previous studies by Çezik and Saraçoğlu [20]. Çezik and Saraçoğlu [20] showed that 2% and 4% postharvest calcium chloride application were effective doses in preserving the quality and biochemical properties of strawberry fruits. In this study, calcium chloride doses were determined as 2%, 4% and 6% by taking the findings of these researchers as reference and the effects of these doses especially on individual phenolic compounds, organic acids, and quality properties of fruits were investigated. This study was designed according to an experimental design consisting of three replications (1 kg of fruit per replicate), 3 doses of calcium chloride (2% CaCl2, 4% CaCl2 and 6% C CaCl2) and different storage periods (5, 10 and 15 days). Accordingly, the fruits were immersed in 0% (control, pure water), 2%, 4% and %6 CaCl2 solutions for 10 min, respectively. Then, the fruits were air-dried on blotting paper and placed in perforated polyethylene (PE) bags and placed in cold storage (0 ± 0.5 °C and 90 ± 5 RH) for storage for 15 days. The PE bag was chosen to hold 1 kg of strawberry fruit with a thickness of 0.01 mm and dimensions of 30 cm × 40 cm. Measurements were taken at the beginning of storage (harvest) and every 5 days for each control and CaCl2 application during the 15-day storage period.

Determination of weight loss and decay rate

Weight loss (%) of strawberry fruits was measured using a digital precision scale (0.01 g scale). Weight loss was calculated according to Hosseini et al. [11] as follows:

[(fruit weight at the beginning of storage—fruit weight at storage time) / (fruit weight at the beginning of storage)] × 100.

The decay rate was determined by evaluating 30 fruits. Fruit decay rate (%) was scored as 0 = no decay, 1 = light decay (decay covers at most 25% of the fruit surface), 2 = moderate decay (decay covers between 25 and 50% of the fruit surface) and 3 = severe decay (decay covers more than 50% of the fruit surface). Accordingly, the decay rate was determined using the following formula: [(1 × FN1 2 × FN2 3 × FN3) × 100/(3 × FN)].

In the formula; FN is the total number of fruits, FN1, FN2 and FN3 are the number of fruits showing different decay scores [21].

Determination of soluble solids content (SSC), acidity, pH and respiration rate

Soluble solids content (SSC) (%) was measured with a portable hand refractometer (ATC, BX50, Türkiye). Acidity was determined by titrating 10 mL of juice mixed with 10 mL of distilled water against 1/10 N NaOH using phenolphthalein as an indicator, expressed as a percentage [22]. pH levels were measured with a table pH meter (Thermo, OrionStar A111, USA). For respiration rate, 100 g of fruit per replicate were placed in 2000 mL glass bottles with a 2 cm hole in the cap. A CO2 sensor probe (Testo 535 CO2 Meter, Germany) was inserted into the hole and sealed with parafilm to prevent leakage [23]. Experiments were performed in a controlled environment. Results are given in mg CO2 kg−1 h−1, calculated using

$$\:RR=\frac{{\Delta\:}\text{C}\text{O}2\times\:\:\text{M}\text{C}\text{O}2\:\times\:\:\text{V}\text{h}}{Vm\:x\:m\:x\:{\Delta\:}\text{t}}$$

ΔCO2=CO2(t2)—CO2(t1)

$$\:\text{V}\text{m}=\frac{R\:x\:T}{\text{P}}$$

Here;

RR: Respiration rate, mg CO2 kg−1 h.−1

ΔCO2: CO2 bulk density, ppm, 10–6 L L.−1

MCO2: Molecular weight of CO2 gas, 44.01 g mol.−1

Vh: Bottle volume, L.

m: Fruit weight, kg.

Δt: Duration of the experiment, h.

CO2(t1): Initial CO2 concentration, ppm, 10–6 L L.−1

CO2(t2): CO2 concentration at the end of the experiment, ppm, 10–6 L L.−1

Vm: Molar volume of gas, L mol.−1

R: Gas constant, 0.08206 L−1 mol−1 1 K−1.

T: Temperature, K.

P: Pressure, atm.

Organic acid determination

Organic acids were extracted from fresh samples using a modified method by Bevilacqua and Califano [24]. 50 g of sample was treated with 10 mL of 0.009 N H2SO4, homogenized, and centrifuged at 14,000 rpm for 15 min. The supernatants were filtered first through filter paper and then twice through a 0.45 m membrane filter (Millipore Millex-HV Hydrophilic PVDF, Millipore, USA) before being passed through a SEP-PAK C18 cartridge. The SEP-PAK C18 cartridge was passed through 2.5 ml of methanol and then through empty air twice to activate it. It was then injected into the HPLC device (Agilent HPLC 1100 series). The diode array detector (Agilent, USA) in the system was set to 210 nm wavelengths and the Aminex HPX-87H column was used. 0.009 N H2SO4 filtered through a 0.45 µm membrane filter was used as the mobile phase and the results were expressed as mg 100 g−1. In this study malic, citric, fumaric, oxalic, tartaric, succinic, and ascorbic acid standards (Sigma-Aldrich Germany) were determined using the Aminex HPX-87H column in an HPLC device.

Phenolic compound determination

For phenolic compound analysis, 250 g of fruit were homogenized and mixed with distilled water (1:1 ratio). The mixture was centrifuged at 15,000 rpm for 15 min. Supernatants were filtered through coarse filter paper and then through a 0.45 µm membrane filter (Millipore Millex-HV Hydrophilic PVDF, USA) before injection into an Agilent HPLC system. Chromatographic separation used a 250 × 4.6 mm, 4 μm ODS column (HiChrom, USA) with a mobile phase of solvent A (methanol: acetic acid: water-10:2:28) and solvent B (methanol: acetic acid: water—90:2:8). Detection wavelengths were 270 nm and 280 nm. The flow rate was 1 ml/min, and 20 µl was injected. Standards (catechin, chlorogenic, ferulic, gallic, o-coumaric, p-coumaric, protocatechuic, quercetin, rutin and syringic) were from Sigma-Aldrich (Germany) with ≥ 99% purity [25].

Statistical analysis

Data were subjected to two-way ANOVA using SAS software, Version 9.1 (SAS Institute Inc., Cary, NC, USA). When the F-test showed significance, means were compared using Tukey’s post-hoc test. Pearson’s pairwise correlations were used to assess relationships between the studied traits, utilizing the 'corrplot' package in R. The interactions between factors (storage periods and calcium chloride doses) and traits were analyzed via principal component analysis (PCA) with the 'ggplot2' package in R. Heatmap analysis was conducted using the 'bioconductor' package in R [26].

Results

Weight loss, SSC, acidity and pH

According to the storage time x CaCl2 interaction, weight loss in strawberry fruits was found to be statistically significant at P < 0.05 level (Table 1). In this study, CaCI2-treated fruits showed significantly lower weight loss than control fruits, especially on the 5th and 10th days of storage, while at the end of storage (15th day), lower weight loss was detected only in fruits treated with 6% CaCl2. On the 5th day of storage, weight loss was determined as 2.75% in the control group, while it was 0.59% in 6% CaCl2 application. On the 15th day of storage, weight loss was determined as 4.57% in the control group, while it was 3.93% in 6% CaCl2 application. The effects of calcium chloride applications on weight loss were found to be statistically insignificant regardless of storage time (F: 0.96). However, the effects were significant when storage time was taken into account (P ≤ 0.05; F: 3.82). Therefore, it was determined that calcium chloride applications were more effective than the control group in reducing increases in weight loss, especially when storage time was taken into account.

Table 1 Effect of postharvest calcium chloride treatments on fruit quality of strawberry
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The SSC levels in strawberries showed a consistent decreasing trend depending on the storage duration. It was found that CaCl2 treatments significantly slowed down this decrease in SSC levels compared to the control group, with statistical significance at the P < 0.05 level (Table 1). On the 5th day of storage, the SSC level in the control group was 9.88%, while it was 10.87% in the 6% CaCl2 treatment group. By the end of the storage period (15th day), the SSC level in the control group was 7.82%, whereas it was 9.36% in the 6% CaCl2 treatment group. It was found that calcium chloride treatments were statistically insignificant when considered independently of storage time. However, during storage, calcium chloride treatments were more effective than the control group in mitigating the decrease in SSC, and this effect was statistically significant (F: 3.49).

The effect of post-harvest CaCl2 applications on TA values of strawberry fruits was found to be statistically significant depending on the storage period (P < 0.001), but the effect of calcium chloride applications alone was found to be insignificant, independent of the storage period. TA showed a consistently decreasing trend throughout the study (Table 1). According to the data presented in Table 1, only the samples treated with 6% CaCl2 differed significantly from the control samples on the 5th and 10th days. By the end of the storage period (15th day), only the samples treated with 4% CaCl2 showed a significant difference from the control samples. A negative correlation was observed between acidity and pH values in strawberry fruits throughout the storage period. While acidity decreased during storage, pH increased. According to ANOVA results, calcium chloride treatments were found to be more effective than the control group in preventing changes in acidity and pH, depending on the storage duration.

Decay and respiration rates

According to the storage time x CaCl2 interaction, the decay rate of strawberry fruits was found to be statistically significant (P < 0.001), except for the 15-day storage period. In the study, at the end of 5 and 10 days of storage, 4% and 6% of CaCl2 treated fruits showed significantly lower decay rates than the control fruits (Table 1). Moreover, the lowest decay rates were observed in 4% (0.79% decay rate) and 6% (0.65% decay rate) CaCl2-treated fruits at the end of 5 days of storage and in 6% CaCl2 (1.26% decay rate) treated fruits at the end of 10 days of storage.

The respiration rate of strawberry fruits was found to be statistically significant (P < 0.001). Accordingly, at the end of 5 days of storage, respiration rates of all CaCl2 applied fruits were found to be significantly lower than control fruits. On the 15th day of storage, no statistically significant difference was found between the applications and the control group. In study, at the end of 10 days of storage, 6% CaCl2-treated fruits showed significantly lower respiration rates than the control fruits, while 2% CaCl2-treated fruits showed the same respiration rates as the control fruits. Additionally, the lowest respiration rates were detected in fruits treated with 6% CaCl2 after 10 and 15 days of storage. At the end of 5 days of storage, there was no difference between the applications in terms of minimum respiration rate. The study's ANOVA statistical analysis of respiration rate and decay rate showed that the F values for the interaction between storage time and calcium chloride were 7.84 and 9.07, respectively, and were significant at the P < 0.001 level. This indicates that the effect of calcium chloride treatments becomes apparent with storage time and demonstrates that these treatments help maintain the quality characteristics of the fruits.

Organic acids

The amounts of organic acids and vitamin C (ascorbic acid) detected in strawberry fruits were found to be statistically significant (P < 0.001). It was determined that the most common compound found in strawberry fruits in terms of organic acids was malic acid, followed by citric acid, succinic acid and oxalic acid, respectively (Table 2). In the study, according to storage time x CaCl2 interactions, it was observed that 6% CaCl2 for malic acid, 6% CaCl2 for oxalic acid and 4% CaCl2 for succinic acid were the highest organic acids in all three storage times compared to control group fruits. Additionally, while levels varied with storage time, 4% and 6% CaCl2-treated fruits generally had higher citric acid, and 6% CaCl2-treated fruits had higher fumaric acid, compared to the control fruits. On the other hand, in terms of tartaric acid, which is one of specific organic acids, 6% CaCl2 treated fruits were found to contain higher amounts of organic acids compared to the control fruits, especially on the 5th and 10th days of storage. Also, in terms of vitamin C, although it varied according to different storage periods, in general, 6% CaCl2-treated fruits contained significantly more vitamin C than control fruits (Table 2). In the study, therefore, it was concluded that, in general, organic acid and vitamin C losses were prevented more in 6% CaCl2-treated fruits than in control group fruits, although it varied according to specific organic acids and different storage periods. In addition, it was determined that the most common compound found in strawberry fruits in terms of organic acids was malic acid, followed by citric acid, succinic acid and oxalic acid, respectively (Table 2).

Table 2 Effect of postharvest calcium chloride treatments on organic acid contents of strawberry fruits (mg 100 g−1 FW)
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Phenolic compounds

It was found that the predominant phenolic compound in strawberry fruits was gallic acid, with chlorogenic acid and catechin following in abundance (Tables 3 and 4). In the research, gallic acid showed a decrease during the storage period and at the end of storage (15th day) it was determined as 17.23 mg 100 g−1 in the control group, while it was determined as 18.32 mg 100 g-1 in 6% CaCl2 application. In the storage time × CaCl2 interaction, the change in gallic acid content was found to be statistically significant at p ≤ 0.001 (F:19.23). While the amount of chlorogenic acid was 8.38 mg 100 g-1 on the 15th day of storage, it was determined as 9.84 mg 100 g-1 in 6% CaCl2 application. When the catechin content was examined, it was seen that it increased on the 5th day of storage compared to the harvest period and tended to decrease on the 10th and 15th days. Additionally, although varying with storage time, fruits treated with 4% CaCl2 generally had the highest levels of gallic and o-coumaric acids, while fruits treated with 6% CaCl2 had the highest level of protocatechuic acid. The highest levels of syringic acid were observed in fruits treated with both 4% and 6% CaCl2 compared to the control group. On the other hand, when the other phenolic compound amounts determined in the study were analyzed; the highest phenolic compound amounts were determined in 6% CaCl2 treatment for chlorogenic acid and p-coumaric acid in all three storage periods, in 4% CaCl2 treatment for ferulic acid on the 5th and 10th days of storage, and in 2% CaCI2 and 6% CaCl2 treatments on the 10th and 15th days of storage for catechin and quercetin, respectively. In terms of rutin compound, the highest amount was observed in 4% CaCl2-treated fruits after only 15 days of storage. Overall, both 4% and 6% CaCl2 treatments were more effective than the control in preventing losses of phenolic compounds during storage. Gallic acid was the most common phenolic compound in strawberries, followed by chlorogenic acid and catechin.

Table 3 Effect of postharvest calcium chloride treatments on phenolic compounds of strawberry fruits (mg 100 g−1 FW)
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Table 4 Continue of Table 3 (mg 100 g−1 FW)
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Relationships between quality attributes, organic acids, phenolic compounds, and calcium chloride during storage

The correlation distributions of various organic acids in strawberry fruits are depicted in the basic coordinate plane of PCA identification in Fig. 1. Both the agro-morphological characteristics and organic acid content of strawberry fruits changed during cold storage, with the effects of CaCl2 treatments varying depending on the dosage. The analysis showed that the first two principal component axes explained 85.08% of the total variation, underscoring their importance in the evaluation. When Fig. 2 is examined, it is seen that malic acid and ascorbic acid form a separate group, separate from weight loss, pH, degradation rate and respiration rate. Similarly, the correlation distributions of various phenolic compounds in strawberry fruits are illustrated in the basic coordinate plane of PCA description in Fig. 2. The phenolic compound contents of strawberry fruits also changed during cold storage, with effects of CaCl2 treatments varying by dose. The analysis indicated that the first two principal component axes accounted for 80% of total variation, with the first principal component axis explaining 66% and second 14%. These axes were thus deemed crucial for the analysis. Catechin, quercetin, chlorogenic acid, o-coumaric acid, and syringic acid showed parallelism and were in the same plane. Similarly, ferulic acid, gallic acid, protocatechuic acid, and p-coumaric acid formed statistically close groups, while rutin exhibited different changes from the other compounds.

Fig. 1
figure 1

Distribution of agro morphological and organic acids according to principal component analysis grouped by storage periods and calcium chloride treatments

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Fig. 2
figure 2

Distribution of phenolic compounds according to principal component analysis grouped by storage periods and calcium chloride treatments

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Heatmap analysis was conducted to assess the impact of storage periods and CaCl2 doses on various biochemical properties of strawberry fruits. In this analysis, a shift towards red on the color scale indicates an increase in statistical significance. According to the heatmap results, changes in respiration rate, weight loss, pH, and decay rate for CaCl2 treatments at 2–4% on the 15th day, as well as for the control group on 10th and 15th days, were more significant compared to other treatments (indicated by red color). Conversely, changes in organic acids and phenolic compounds (except for quercetin, rutin, and catechin) in the control harvest group were identified as the most statistically significant parameters (red color). However, phenolic compounds and organic acids formed a less significant cluster (blue color), particularly on the 15th day of the control group (Fig. 3).

Fig. 3
figure 3

Hatmap analysis of fruit traits and bioactive compounds according to treatments and storage periods. The blue to red color scale shows the minimum to maximum values for each trait

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Weight loss was positively correlated with decay rate (r = 0.77, p ≤ 0.001), pH (r = 0.78, p ≤ 0.001), and respiration rate (r = 0.50, p ≤ 0.001), while it was negatively correlated with SSC and AC. Organic acids were highly positively correlated with each other, and phenolic compounds showed a similar high positive correlation among themselves. Ascorbic acid exhibited a positive correlation with citric acid (r = 0.87, p ≤ 0.001), malic acid (r = 0.92, p ≤ 0.001), oxalic acid (r = 0.90, p ≤ 0.001), tartaric acid (r = 0.86, p ≤ 0.001), succinic acid (r = 0.78, p ≤ 0.001), and fumaric acid (r = 0.76, p ≤ 0.001). Similarly, vitamin C showed a positive correlation with phenolic compounds, specifically ascorbic acid correlated positively with gallic acid (r = 0.79, p ≤ 0.001), protocatechuic acid (r = 0.90, p ≤ 0.001), p-coumaric acid (r = 0.86, p ≤ 0.001), chlorogenic acid (r = 0.86, p ≤ 0.001), o-coumaric acid (r = 0.88, p ≤ 0.001), and ferulic acid (r = 0.81, p ≤ 0.001) (Fig. 4).

Fig. 4
figure 4

Relationship among physicochemical properties of strawberry fruits. The color gradient ranging from red to blue represents correlation values between -1 and + 1. *, **, and *** denote significance levels at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001, respectively. WL: weight loss, DR: decay rate, SSC: soluble solids contents, AC: acidity, RR: respiration rate, CA: citric acid, MA: malic acid, OA: oxalic, TA: tartaric acid, SA: succinic acid, FA: fumaric acid, AA: ascorbic acid, GA: gallic, Cat: catechin, Prt: protocatechuic, SYR: syringic, P–C: p-coumaric, Chl: chlorogenic, O-Q: o-coumaric, Fer: ferulic, Quer: quercetin

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Discussion

Weight loss in fruits is primarily caused by metabolic processes like respiration and transpiration. In this study, it was observed that weight loss increased during storage, and it was determined that CaCl2 doses, especially on the 5th and 10th days of storage, prevented weight loss more than the control group.This effect is linked to the generally lower respiration rates observed in CaCl2-treated fruits compared to the control group (Table 1). For instance, Chen et al. [27] treated strawberries with 0%, 1%, and 4% CaCl2 and stored them at 4 °C for 15 days, finding that fruits treated with 1% and 4% CaCl2 had significantly less weight loss compared to the controls. Similarly, Turmanidze et al. [28] found that strawberries stored at 0 °C and 95% relative humidity for 8 days experienced less weight loss when treated with 2% CaCl2. Shahzad et al. [29] observed that strawberries stored at 4 °C and 80–85% relative humidity for 15 days showed significantly reduced weight loss when treated with 6% CaCl2. Additionally, Wan Mahfuzah et al. [30] reported that strawberries stored at 10 °C for 12 days showed the least weight loss with 1% CaCl2 treatment, compared to other treatment levels and the control. The findings of this study are consistent with previous research on the impact of CaCl2 treatment in reducing weight loss in stored strawberries.

Chen et al. [27] found that strawberries treated with 1% CaCl2 and stored for 15 days had a higher soluble solids content (SSC) compared to the control fruits. Similarly, García et al. [31] reported that in Spanish strawberries (Fragaria ananassa cv. Tudla) stored at 18 °C for 3 days, those treated with 1% CaCl2 exhibited the highest SSC levels compared to the controls. In another study, Lateef et al. [32] investigated the 'Sweet Charlie' strawberry variety, applying two different concentrations of CaCl2 (1% and 2%) and found that both treatments resulted in significantly higher SSC than the control fruits. They also noted that strawberries treated with 2% CaCl2 had the highest SSC content. EL-Sayed et al. [33] observed similar results in strawberries stored at 10 °C for 7 days, where fruits treated with 1% and 2% CaCl2 had significantly higher SSC than the controls. These findings, along with those in this study, demonstrate that CaCl2 treatment consistently increases SSC in stored strawberries. This effect may be attributed to calcium's role in slowing down the ripening and aging processes in strawberries, which helps preserve total sugars and consequently leads to higher SSC levels [34].

EL-Sayed et al. [33] observed that in strawberries stored for 7 days, 2% CaCl2 treated fruits contained significantly more TA than control fruits. Similar to this literature study on TA value, CaCI2 application increased the TA value of strawberry in this study. Regarding the increase in TA value in CaCI2-treated strawberries; it is known that fruit acidity value is directly related to the preservation of total sugar content in fruits, but it is also known that applied CaCI2 can preserve more total sugars by ripening the fruit later and thus TA value appears in higher amounts [35]. In this study, the interaction between storage duration and CaCl2 treatments showed that, on the 15th day of storage, all CaCl2 treatments better preserved the TA content compared to the control group. The 2% CaCl2 treatment preserved approximately 13% more TA compared to the control group. The findings of this study are consistent with those of other researchers. The lack of exact similarity in results is thought to be influenced by the strawberry variety used, cultural practices, and ecological factors in the study.

Turmanidze et al. [36] reported that for strawberries stored at 20 °C and 90% relative humidity for 8 days, the pH values of fruits treated with 1% and 2% CaCl2 were not significantly different from those of the control fruits. Wan Mahfuzah et al. [30] found that for strawberries stored at 10 °C for 12 days and treated with three different doses of CaCl2 (1%, 2%, and 3%), all treated fruits showed the same pH values as the control fruits. In our study, the pH value of the control fruits showed a continuous increasing trend throughout the storage period. CaCl2 treatments were more effective in limiting this increase compared to the control. This suggests that CaCl2, which reduces respiration rates, helps prevent biochemical changes in the fruits. Consequently, our findings are similar to those of other researchers [30, 36]. Differences between studies are generally attributed to variations in strawberry varieties, cultural practices, CaCl2 dosages, and storage conditions [20].

In addition, it is known that pH values decreased in CaCl2 -treated strawberries as a result of decreased respiration rate compared to control group fruits [20]. Chen et al. [27] reported that in strawberries stored for 15 days, 1% CaCl2-treated fruits had significantly lower decay rates than control fruits. García et al. [31] reported that in Spanish strawberries stored at 18 °C for 3 days, 1% CaCI2-treated fruits showed less decay than the control. Shahzad et al. [29] reported that in strawberries stored for 15 days, 5% CaCl2-treated fruits showed minimum decay rate compared to untreated fruits. Çezik and Saraçoğlu [20] applied CaCl2 at three different doses (0%, 2% and 4%) on strawberry variety 'Monterey' stored for 21 days at 90% relative humidity and found less decay in 2% CaCl2 treated fruits than in control fruits. The results of the above literature studies on the effect of CaCl2 application on fruit decay rate in strawberry were in parallel with the results of this study. As a matter of fact, Moline [37] concluded that CaCl2 applied to strawberries acts as an important barrier against pathogens on the fruit surface and effectively minimizes fruit decay. In a study conducted by Matar et al. [15], it was demonstrated that in modified atmosphere packaging applications, the shelf life of fruits with reduced respiration rates was extended while preserving their quality and biochemical properties. It has been determined that strawberries coated with limonene liposomes have lower respiration rates compared to the control and alginate coatings [14]. Similarly, it has been reported that the pH values of strawberries coated with liposomes were significantly lower and their anthocyanin content was higher. These results suggest that limonene liposomes may be effective in preserving the post-harvest quality of strawberries [14].

Similar to the results of this study in terms of respiration rate, some researchers have reported that there is a linear relationship between the increase in CaCl2 in fruits and the decrease in fruit respiration rates. The researchers emphasized that lower amount of CO2 is secreted in CaCl2-treated fruit, metabolic activities of the fruits are reduced and thus fruit respiration rates are reduced [38].

Turmanidze et al. [36], in their study on strawberries stored for 8 days, reported that phenolic compound losses were significantly more prevented in 1% and 2% CaCl2-treated fruits than in control fruits. Shahzad et al. [29] reported that phenolic compounds were significantly better preserved in 6% CaCl2-treated fruits than in control fruits in their study in which they stored strawberry fruit at 4 °C and 80–85% relative humidity for 15 days. Öcalan et al. [39] reported that phenolic compound amounts were higher in 4% CaCl2-treated fruits compared to 2% CaCl2-treated fruits and control fruits in strawberries stored at 1–2 °C for 14 days and treated with two different doses (2% and 4%) of CaCl2. The results of this study were in parallel with the above literature results on phenolic compounds. Phenolic compounds show a protective shield against oxidative stress caused by the scavenging of free radicals in fruit cells. Therefore, it is known that phenolic compounds, which have important functions in strawberries as in most fruits, can increase significantly as a result of decreased softening process and respiration rate in strawberries treated with CaCl2 [38].

According to Turmanidze et al. [36], strawberries that were treated with 2% CaCl2 and stored for 8 days exhibited significantly higher levels of vitamin C compared to the control group. Similarly, Sohail et al. [40] reported that peaches stored at 35 °C for 15 days, and treated with various doses of CaCl2 (1%, 2%, and 3%), showed better preservation of vitamin C content, with the highest retention in fruits treated with 3% CaCl2. Veltman et al. [41] also observed that CaCl2 had a significant effect on maintaining vitamin C levels in peaches. The results of this study align with those in the literature on the preservation of organic acids. However, differences in the optimal CaCl2 dose and vitamin C content between studies may be attributed to factors such as variations in fruit types, CaCl2 concentrations, storage durations, and conditions [27]. Ascorbic acid, a nutrient crucial for metabolic activities in fruits, is prone to oxidation and degradation, especially during processing and storage, due to reduced ascorbate peroxidase enzyme activity [41]. It is well known that CaCl2 application can significantly slow the oxidation of vitamin C by enhancing the activity of various catalytic enzymes essential for fruit biosynthesis, thereby preserving vitamin C levels [42].

Conclusions

The study determined that post-harvest 6% CaCl2 application prevented weight loss more than the control group on the 5th and 10th days of storage, and its effect was statistically insignificant regardless of the storage period.There was a decrease in SSC levels during storage and it was found that especially 6% CaCl2 application prevented the decrease in SSC rate more. It was observed that especially CaCl2 doses significantly reduced decay on the 5th and 10th days of storage. Respiration rate varied during storage and CaCl2 treatments preserved the change in respiration rate more than the control group. Additionally, biochemical analysis showed that the losses of phenolic compounds, organic acids, and vitamin C were better prevented in fruits treated with 4% and 6% CaCl2, with 6% CaCl2 being particularly effective in preserving organic acids and vitamin C. Therefore, the study concluded that a 6% CaCl2 treatment is generally effective in maintaining the quality and extending the shelf life of strawberries. In this study, the effects of calcium chloride on the individual phenolic and organic acid contents of strawberry fruits were revealed and in this respect, it is particularly important to provide a valuable literature source for future research.

Data availability

Data will be available on request to corresponding authors.

Abbreviations

H:

Hour

Min:

Minute

pH:

Power of hydrogen

SSC:

Soluble solids content

TA:

Titratable acidity

References

  1. Sharma RR. Growing strawberries. Lucknow, India: International Book Distributing Co.; 2002. p. 1–99.

    Google Scholar 

  2. Redondo-Gómez S, García-López JV, Mesa-Marín J, Pajuelo E, Rodriguez-Llorente ID, Mateos-Naranjo E. Synergistic effect of plant-growth-promoting rhizobacteria improves strawberry growth and flowering with soil salinization and ıncreased atmospheric CO2 levels and temperature conditions. Agronomy. 2022;12:2082.

    Article  Google Scholar 

  3. Moreira AFP, De Resende JTV, Shimizu GD, Hata FT, Do Nascimento D, Oliveira LVB, Zanin DS, Mariguele KH. Characterization of strawberry genotypes with low chilling requirement for cultivation in tropical regions. Sci Hortic. 2022;292:110629.

    Article  CAS  Google Scholar 

  4. TÜİK. Türkiye İstatistik Kurumu. Available at www.tuik.gov.tr. 2023;(Erişim tarihi: 1 Temmuz 2024).

  5. Kang C, Darwish O, Geretz A, Shahan R, Alkharouf N, Liu Z. Genome-scale transcriptomic insights into early-stage fruit development in woodland strawberry Fragaria vesca. Plant Cell. 2013;25:1960–78.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  6. Barbey C, Hogshead M, Schwartz AE, Mourad N, Verma S, Lee S, Whitaker VM, Folta KM. The genetics of differential gene expression related to fruit traits in strawberry (Fragaria ×ananassa). Front Genet. 2020;10:1317.

    Article  PubMed  PubMed Central  Google Scholar 

  7. Given NM, Venis MA, Grierson D. Hormonal regulation of ripening in the strawberry, a non-climacteric fruit. Plant. 1988;174:402–6.

    Article  CAS  Google Scholar 

  8. Wang SY, Zheng W. Effect of plant growth temperature on antioxidant capacity in strawberry. J Agric Food Chem. 2001;49:4977–82.

    Article  PubMed  CAS  Google Scholar 

  9. Afrin S, Giampieri F, Gasparrini M, Forbes-Hernandez T, Varela-López A, Quiles J, Mezzetti B, Battino M. Chemopreventive and therapeutic effects of edible berries: A focus on colon cancer prevention and treatment. Molecules. 2016;21:169.

    Article  PubMed  PubMed Central  Google Scholar 

  10. Kim AN, Lee KY, Jeong EJ, Cha SW, Kim BG, Kerr WL, Choi SG. Effect of vacuum–grinding on the stability of anthocyanins, ascorbic acid, and oxidative enzyme activity of strawberry. LWT. 2021;136(1):110304.

    Article  CAS  Google Scholar 

  11. Hosseini MS, Zahedi SM, Abadía J, Karimi M. Effects of postharvest treatments with chitosan and putrescine to maintain quality and extend shelf-life of two banana cultivars. Food Sci Nutr. 2018;6:1328–37.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  12. Zhang L, Wang L, Zeng X, Chen R, Yang S, Pan SA. Comparative transcriptome analysis reveals fruit discoloration mechanisms in postharvest strawberries in response to high ambient temperature. Food Chem.: X. 2019;2:100025.

  13. Rashid A, Qayum A, Liang Q, Kang L, Raza H, Chi Z, Chi R, Ren X, Ma H. Preparation and characterization of ultrasound-assisted essential oil-loaded nanoemulsions stimulated pullulan-based bioactive film for strawberry fruit preservation. Food Chem. 2023;422:136254.

    Article  PubMed  CAS  Google Scholar 

  14. Dhital R, Mor NB, Watson DB, Kohli P, Choudhary R. Efficacy of limonene nano coatings on post-harvest shelf life of strawberries. LWT – Food Sci. Technol. 2018; 97; 124–134.

  15. Matar C, Gaucel S, Gontard N, Guilbert S, Guillard V. Predicting shelf life gain of fresh strawberries ‘Charlotte cv’ in modified atmosphere packaging. Postharvest Biol Technol. 2018;142:28–38.

    Article  CAS  Google Scholar 

  16. Xu Y, Charles MT, Luo Z, Mimee B, Z Tong, Roussel D, Rolland D, P Véronneau Y. Preharvest UV-C treatment affected postharvest senescence and phytochemicals alternation of strawberry fruit with the possible involvement of abscisic acid regulation. Food. Chem. 2019; 299: 125138.

  17. Mozhdehi F, Abdossi V, Kalatejari S. Effect of packing system, calcium chloride and chlorine on the storage life of strawberry fruits (Fragaria ananassa cv. Kordistan). Journal of Basic & Applied Sci. 2021;8(2):393–398.

  18. Conway WS, Sams CE, Kelman A. Enhancing the natural resistance of plant tissues to postharvest disease through calcium applications. HortSci. 1994;29:751–4.

    Article  CAS  Google Scholar 

  19. Sams CE. Preharvest factors affecting postharvest texture. Postharvest Biol Technol. 1999;15:249–54.

    Article  Google Scholar 

  20. Çezik F, Saraçoğlu O. The effect of pedicel length and post-harvest calcium chloride application on the storage life of strawberry fruit. Applied Fruit Sci. 2024;66:843–53.

    Article  Google Scholar 

  21. Cao S, Hu Z, Pang B, Wang H, Xie H, Wu F. Effect of ultrasound treatment on fruit decay and quality maintenance in strawberry after harvest. Food Cont. 2010;21:529–32.

    Article  CAS  Google Scholar 

  22. Hanif A, Ahmad S, Jaskani MJ, Ahmad R. Papaya treatment with putrescine maintained the overall quality and promoted the antioxidative enzyme activities of the stored fruit. Sci Hortic. 2020;268:109367.

    Article  CAS  Google Scholar 

  23. Huang H, Danao M, Rausch K, Singh V. Diffusion and production of carbon dioxide in bulk corn at various temperatures and moisture contents. J Stored Prod Res. 2013;55:21–6.

    Article  Google Scholar 

  24. Bevilacqua AE, Califano AN. Determination of organic acids in dairy products by high performance liquid chroma-tography. J Food Sci. 1989;54:1076–9.

    Article  CAS  Google Scholar 

  25. Rodriguez-Delgado MA, Malovana S, Perez JP, Borges T, Garcia-Montelongo FJ. Separation pf phenolic compounds by high-performance liquid chromatography with absorbance and fluorimetric detection. J Chromatography. 2001;912:249–57.

    Article  CAS  Google Scholar 

  26. Gentleman RC, Carey VJ, Bates DM, Bolstad B, Dettling M, Dudoit S, Ellis B, Gautier L, Ge Y, Gentry J, Hornik K, Hothorn T, Huber W, Lacus S, Irizarry R, Leisch F, Li C, Maechler M, Rossini AJ, Sawitzki G, Smith C, Smyth G, Tierney L, Hanh JHY, Zhang J. Bioconductor: open software development for computational biology and bioinformatics. Genome Biol. 2004;5(10):1–16.

    Article  Google Scholar 

  27. Chen F, Liu H, Yang H, Lai S, Cheng X, Xin Y, Yang B, Hou H, Yao Y, Zhang S, Bu G, Deng Y. Quality attributes and cell wall properties of strawberries (Fragaria annanassa Duch.) under calcium chloride treatment. Food Chemist. 2011;126(2):450–459.

  28. Turmanidze T, Gulua L, Jgenti M, Wicker L. Potential antioxidant retention and quality maintenance in raspberries and strawberries treated with calcium chloride and stored under refrigeration. Braz J Food Technol. 2017;20:e2016089.

    Article  Google Scholar 

  29. Shahzad S, Ahmad S, Anwar R, Ahmad R. Pre-storage application of calcium chloride and salicylic acid maintain the quality and extend the shelf life of strawberry. Pak J Agri Sci. 2020;57(2):339–50.

    Google Scholar 

  30. Wan Mahfuzah WI, Zulkifli MS, Latifah MN, Fauziah O. Evaluations for effectiveness of calcium chloride treatment on the postharvest quality of strawberry. ISHS Acta Horticultur. 2012;1012:VII.

  31. García JM, Herrera S, Morilla A. Effects of postharvest dips in calcium chloride on strawberry. J Agric Food Chem. 1996;44(1):30–3.

    Article  Google Scholar 

  32. Lateef MA, Noori AM, Saleh YM, Al-Taey DKA. The effect of foliar spraying with salicylic acid and calcium chloride on the growth, yield, and storage traits of two strawberry cultivars, Fragaria x ananassa Duch. Int J Agricult Stat Sci. 2021;17(2):611–5.

    Google Scholar 

  33. EL-Sayed SSF, EL-Mogy MM, Mahmoud GA. Potassium silicate and calcium chloride improve production and shelf-lifeof strawberries. Fayoum Journal of Agricultural Research and Develop. 2023;37(4):736–759.

  34. Sharma RR, Krishna H, Patel VB, Dahuja A, Singh R. Fruit calcium content and lipoxygenase activity in relation to albinism disorder in strawberry. Scientia Horticultur. 2006;107:150–4.

    Article  CAS  Google Scholar 

  35. Amiri S, Rezazad BL, Malekzadeh S, Amiri S, Mostashari P, Ahmadi GP. Effect of Aloe vera gel-based active coatingin corporated with catechin nanoemulsionand calcium chloride on postharvest quality of fresh strawberry fruit. Journal of Food Processing and Preserva. 2022;46(10):e15960.

    Article  CAS  Google Scholar 

  36. Turmanidze T, Gulua L, Jgenti M, Wicker L. Effect of calcium chloride treatments on quality characteristics of blackberry, raspberry and strawberry fruits after cold storage. Turkish Journal of Agriculture - Food Science and Techno. 2016;4(12):1127–33.

    Article  Google Scholar 

  37. Moline HE. Preharvest management for postharvest biological control. Biological Control of Postharvest Diseases-Theory and Practice. CL Wilson and ME Wisniewski, eds. CRC Press, Boca Raton, Florida, The United States of America. 1994;57–62.

  38. Wang Y, Xie X, Long LE. The effect of postharvest calcium application in hydro-cooling water on tissue calcium content, biochemical changes, and quality attributes of sweet cherry fruit. Food Chemist. 2014;160:22–30.

    Article  CAS  Google Scholar 

  39. Öcalan ON, Çezik F, Al-Salihi AAM, Çiğdem MR, Yıldız K. (2022). The effect of post-harvest calcium chloride applications on the shelf life quality of strawberry. Turkish Journal of Agriculture - Food Science and Technol. 2022;10(sp1):2701–2707.

  40. Sohail M, Khalil SA, Afridi SR, Rehman UK, Ahmad T, Ullah F. Enhancing post harvest storage life of peach fruits using calcium chloride. Journal of the Chemical Society of Pakist. 2013;35:109–13.

    CAS  Google Scholar 

  41. Veltman RH, Kho RMA, Van-Schaik CR, Sanders MG, Oosterhaven J. Ascorbic acid and tissue browning in pears under controlled atmosphere conditions. Postharvest Biology and Technology Amster. 2000;19:129–37.

    Article  CAS  Google Scholar 

  42. Castello ML, Chiralt A, Fito PJ. Changes in respiration rate and physical properties of strawberries due to osmotic dehydration and storage. J Food Eng. 2010;97(1):64–71.

    Article  CAS  Google Scholar 

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Authors and Affiliations

  1. Ege University, Faculty of Agriculture, Department of Horticulture, İzmir, Türkiye

    Deniz Eroğul & Fatih Sen

  2. Bolu Abant Izzet Baysal University, Faculty of Agriculture, Department of Horticulture, Bolu, Türkiye

    Muttalip Gundogdu

  3. Bolu Abant Izzet Baysal University, Seben İzzet Baysal Vocational School, Department of Plant and Animal Production, Bolu, Türkiye

    Akgul Tas

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DE: Visualization, Conceptualization, Methodology, Data analyzing, Supervision, Writing—original draft, Review, and editing. AT: Investigations, Data collections, Visualization. MG and FS: Methodology, Supervision, Visualization, Writing—original draft, Review, and editing. MG: Methodology, Supervision.

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Eroğul, D., Gundogdu, M., Sen, F. et al. Impact of postharvest calcium chloride treatments on decay rate and physicochemical quality properties in strawberry fruit. BMC Plant Biol 24, 1088 (2024). https://doi.org/10.1186/s12870-024-05792-0

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