Abstract
The aim of this research was to determinate the influence of harvest time and storage duration on several chemical and physical quality parameters of “Cripps Pink” apple cultivar. Fruits were harvested 199 (1Ht), 207 (2Ht), and 214 (3Ht) days after full bloom, and analyzed after 0 (1St), 14 (2Sd), and 30 (3Sd) weeks of storage in a controlled atmosphere (2 °C, 95% relative air moisture, 2% CO2, and 1% O2). Fruit firmness, content of starch, total soluble solids, dry matter, as well as vitamin C, and total acids content were decreased after 14 weeks of storage in each harvest time. The same results were obtained after 30 weeks of storage, except that the pH was increased. Total phenol content and non-flavonoid phenolic fraction decreased during storage, unlike fruit color which did not markedly increased or decreased during storage in every harvest time. Results shown influence of harvest time on storage life and quality of apple fruit, which resulted in progressive content decreasing of some compounds in apple fruit.
El objetivo de esta investigación fue determinar la influencia del tiempo de cosecha y duración en almacenamiento en varios parámetros químicos y físicos de calidad de la variedad de manzana Cripps Pink. Las frutas se cosecharon 199 (1Ht), 207 (2Ht), y 214 (3Ht) días después del florecemiento completo y fueron analizadas después de 0 (1St), 14 (2Sd), y 30 (3Sd) semanas de almacenamiento bajo ambiente controlado (2 °C, 95% de humedad relativa ambiental, 2% CO2 y 1% O2). La firmeza de la fruta, el contenido de almidón, sólidos solubles totales, materia seca, vitamina C, y el contenido total de ácidos disminuyeron después de 14 semanas de almacenamiento en cada tiempo de cosecha. Los mismos resultados se obtuvieron después de 30 semanas de almacenamiento, pero aumentó el pH. El contenido total de fenoles y la fracción fenólica no flavonoide disminuyeron durante el almacenamiento, al contrario del color de la fruta que no aumentó ni disminuyó marcadamente durante el almacenamiento para ninguno de los tiempos de cosecha. Los resultados muestran la influencia del tiempo de cosecha en la vida de almacenamiento y la calidad de la fruta, que resultó en una disminución progresiva del contenido de algunos compuestos de la fruta.
Introduction
In apple production, only a low percentage of apple fruits could be sold immediately after the harvest, while the largest part is stored for an extended period of time to keep them available for a market. Fruit maturity is determined by physiological and structural changes. This includes ethylene synthesis, climacteric cellular respiration, chlorophyll degradation, membrane changes, protein, and aroma volatile synthesis (Brady, Citation1987; Brown, Buchanan, & Hicks, Citation1965; Fellman, Rudell, Mattinson, & Mattheis, Citation2003). Fruit maturity at harvest is the critical factor which has affected flavor development, post harvest ripening and handling the fruit. Harvesting too early may result in a pronounced lack of flavor development, whereas late-harvested fruit undergoes rapid firmness loss during storage (Mattheis, Fellman, Chen, & Patterson, Citation1991). In contrast, Smith (Citation1984), points that the harvest of unripe fruits enhances a number of desirable characteristics, such as extensively prolonging the ripening period and delaying decline in firmness, acidity, and green ground color relative to ripe fruit. Peirs, Lammertyn, Ooms, & Nicolaí (Citation2000) stated in their study that Streif index decreases until the threshold value.
During the storage time, quality of apple fruit is changing. Physical and chemical analysis can establish changes in fruit quality depending on storage time. Aaby, Haffner, and Skrede (Citation2001) in their study on “Gravenstain” apple cultivar reported that firmness and acids decreased during 14 weeks in controlled atmosphere (CA) storage. Recorded values of firmness in harvest time were 8.9 kg cm−2, whereas after storage they were 6.1 kg cm−2 and the values of acids were decreased from 0.86% to 0.68%. In the same report, there was no major difference in total soluble solids (TSS) value, so on harvest time they were 12.1%, whereas after storage they were 11.9%. The same results have been published by Róth et al. (Citation2007) showing a major difference during the storage in TSS. At harvest it was 13.10%, while after 6 months in CA storage it was 13.70%. In the same study on “Gravenstain” apple cultivar, the pH value increased from 3.16 to 3.24. Echeverría, Fuentes, Graell, Lara, and López (Citation2004) reported similar results in their study on the “Fuji” apple, where fruit firmness decreased after 7 months in CA storage from 7.71 kg cm−2 to 7.31 kg cm−2. In this study, C values for color were determined – as 33.8 at harvest time and 34.6 after 3 months of storage; even after the period of 7 months the values remained the same. In the work done by López et al. (Citation2006), who studied “Cripps Pink” apple cultivar fruits, a decrease in firmness was also noted from 9.83 kg cm−2 (after 14 weeks of storage) and 9.55 kg cm−2 (after 24 weeks of storage). The change in value of total phenols also influences apple fruit quality. Phenols increased during the 120 days storage in CA from 52 mg kg−1 to 64 mg kg−1 at “Jonagold” apple cultivar, and the same increase was also reported in “Sampson” apple, from 42 mg kg−1 to 51 mg kg−1 (Leja, Mareczeka, & Benb, Citation2003).
“Cripps Pink” is a late apple cultivar and relatively new on the market, so it is very important to define its storage potential. The aim of this research is to determinate the influence of harvest time on fruit quality and storage life.
Materials and methods
Experimental site and experimental design
“Cripps Pink” apple is cultivated at the plantation “Komin” located in the south part of Croatia (longitude 17°39′, latitude 43°03′). Soil between rows was grass covered and inter row spaces were treated with herbicides. The plantation has high planting density (3330 trees ha−1) on the rootstock M9 at a 3 × 1 m2 planting distance.
Fruits were harvested at three harvest times, with intention to find the optimal time. The first harvest (1Ht) took place 199 days after full bloom, the second (2Ht) 207 days after full bloom, and third (3Ht) 217 days after full bloom. Apple trees were marked with numbers, and the fruits used to provide each sample (20 fruits per sample), were randomly picked by computer generated randomization. However, only healthy and uniformly-sized fruits were taken. Immediately after harvest, fruits were delivered to the laboratory. They were selected according to the average weight, color, and absence of defects. Physical and chemical analyses were done immediately after each harvest (0Sd) on four randomly chosen samples (four replicates) consisting of 30 fruits. So, the experimental design of this research was completely randomized with four replicates, and later statistical analysis of data was carried out accordingly. After analysis, fruits were stored at 2 °C in CA (relative air moisture 95%, CO2 2%, and O2 1%). Then, after 14 (1Sd) and 30 weeks (2Sd) of storage in such conditions, physical and chemical analysis of fruits were taken. In addition, 30 fruits per sample were taken at each harvest and stored at 20 °C for measuring weight loss after storage.
Physical analysis
Weight loss was determined by a single fruit weight measuring unit (Metler Toledo PM 2000 Precision Balance). Flesh firmness was measured on four opposite sides of each fruit with a penetrometer (AOAC, 1995) fitted with an 11.1 mm diameter plunger tip; results were expressed in kg cm−2. Appropriately, Straif index was determined at each harvest. Fruit color was represented by the Hue angle (H), chroma (C; = a2 + b2), and lightness (L; 0: black; 100: white) – whereas a and b define the red-greenness and blue-yellowness, respectively, according to the CIE Lab system on a colorimeter (ColorTec-PCM, Clinton, NJ 08809, USA). Hue angle (H) was calculated as H = arctan b/a (deg; 0°: red-purple; 90°: yellow; 180°: green; 270°: blue).
Chemical analysis
Total acidity (TA; expressed as % of malic acid) was measured according to the AOAC method (AOAC, 1995). Soluble solids content (SSC), expressed as °Brix, were measured using the Abbe refractometer (A. Krüss, Germany) calibrated against sucrose. Total dry matter content was determined after drying ∼5 g of pulp at 105 °C until a stable weight was reached after two subsequent weight measurements. pH was measured with a pH meter (Mettler-Toledo, Switzerland). Evaluation of starch index (the stage of starch hydrolysis) was performed on 20 apples per sample by dipping their cross-sectional halves in an iodine solution (15 g KI + 6 g I2 per litre) for 30 s, and rated visually using a 1–10 EUROFRU scale (1 = full starch; 10 = no starch) (Villatoro et al., Citation2008). The Streif index was computed as the ratio of firmness (F) to the product of TSS and starch index:
Streif index is usually used to estimate the maturity status of apples; within the same cultivar, the lower the Streif index is, the more advanced the fruit maturity (DeLong, Prange, Harrison, Shofield, & De Ell, Citation1999; Streif, Citation1996).
Ascorbic acid was determined using 2,6-dichloroindophenol titrimetric method according to AOAC method 967.21 (2002) and expressed as mg kg−1 of fresh fruit flesh weight (FW).
Total phenolics (TPC) and non-flavonoids (TNF) were determined using the Folin-Ciocalteu colorimetric method described by Ough and Amerine (Citation1998). Results were expressed as mg of gallic acid equivalents (GAE) kg−1 of FW.
Statistical analysis
According to completely randomized experimental design (with four replicates) ANOVA and Tukey's Studentized Range (HSD) tests were performed to determine the significance of differences within examined factors (harvest time and storage duration) as well as between their combination (after proven interaction significance), using the commercial software SAS 9.1® (SAS Institute: Cary, NC). Values are presented as the mean±SD of four replications. p-values lower than 0.05, either from ANOVA or HSD, were considered statistically significant.
Results and discussion
In –, values of analyzed parameters by harvest time and by storage duration, as well as the effects of interaction between them, are presented.
Table 1. Effects of harvest time and storage duration on apple fruit (cv. “Cripps Pink”) basic physical and chemical parameters.
Tabla 1. Efectos del tiempo de cosecha y duración en almacenamiento en los parámetros físicos y químicos básicos de la manzana (cv. Cripps Pink).
In , physical and chemical parameters of fruit ripeness are showed. It is obvious that the fruit firmness did not change depending on harvest time, but it was decreasing during the storage time; then, the apple stored to 14 weeks had maximal value (8.53 cm−2) and after 30 weeks the minimum was (6.78 kg cm−2). Moreover, the other acceptability studies have confirmed decreasing fruit firmness after storage (Aaby et al., Citation2001; Cocci, Rocculi, Romani, & Rosa, Citation2006; Echeverría et al., Citation2004; López et al., Citation2006).
Starch index content showed significant difference at all harvest times depending on the sampling. The starch value decreased with the advanced harvest time (7.6 and 8.9 in the first and the third harvest respectively) (). In study of “Gala” apple, Drake and Eisele (Citation1997), reported similar results, where starch index values were increasing from 3.1 at the first harvest time to 4.4 at the third harvest time (on the scale 1–5). After 14 weeks of storage, the amount of starch was slightly decreased (starch index 8.0), and after 30 weeks no starch was detected (starch index 10.0). This shows that starch was hydrolyzed into monosaccharide, which was already known. Echeverría et al. (Citation2004) confirmed absence of harvest time influence in cultivar Fuji on fruit firmness, TSS, but it had an effect on the starch index.
SSCs (°Brix) showed slight differences among harvest times as well as among storage durations, whereas no significant interaction was detected between those two factors, as reported by others (Lopez et al., 2006; Róth et al., Citation2007). However, at the second and the third harvest time, the SSC (15.1 and 15.0 °Brix) was significantly different from those which were measured in the first harvest time (14.2 °Brix), and also was the lowest after 30 weeks of storage (14.3 °Brix) while total dry matter content was the highest (17.8%) ().
Streif index decreased with each later harvest time; in the first harvest time it was 0.168, the second was 0.145 and the third was 0.116.
The total dry matter content has showed significant differences depending on the harvest time and storage duration (); unlike SSC, harvest time × storage duration interaction was highly significant for this parameter. The total dry matter content showed significant higher content in the second harvest time (178.1 g kg−1 of FW) in comparison with the first and the third harvest times. Generally, the value of total dry matter content had reached maximum immediately after harvest (176.6 g kg−1 of FW) and 30 weeks of storage (177.6 g kg−1 of FW), and the minimum was reached after 14 weeks of storage (168.5 g kg−1 of FW). In general, fruits had the highest total dry matter content after 30 weeks of storage, regardless of the harvest time.
In comparison with the total acids content, there were no significant differences between harvest times. On the other side, comparing average total acids content by storage durations, significant differences between storage durations was measured; as expected, total acids content decreased with the duration of fruits storage (). The fact that the total acids decreased during the storage life has been confirmed by other authors (Aaby et al., Citation2001; Duquea, Barreiro, & Arrabac, Citation1999; López et al., Citation2006).
Apples of all harvests, as well as all storage durations had significantly different pH values; as it could be expected, the lowest pH was found in apples of first harvest time (3.73). Also, the storage of apples significantly increased their pH values (in comparison with the freshly harvested fruits); however, apples which were stored for 30 weeks, had significantly lower pH (3.82) when compared with those stored for 14 weeks (3.96). Similar to our results, Aaby et al. (Citation2001) found a slight increase in pH during a storage period, but it was not statistical significantly.
Values of vitamin C content and the major antioxidant compound classes are statistically elaborated and shown in . All of these parameters are largely influenced by harvest time, storage duration, and their interaction. Loss of vitamin C during the storage is influenced by storage conditions such as temperature, storage duration, and atmosphere (Delaporte, Citation1971; Mapson, Citation1970). As expected, vitamin C content was higher in freshly harvested fruits, and decreased during storage.
Table 2. Effects of harvest time and storage duration on antioxidant compounds contents in apples (cv. “Cripps Pink”).
Tabla 2. Efectos del tiempo de cosecha y duración en almacenamiento en los contenidos de compuestos antioxidantes de la manzana (cv. Cripps Pink).
Apples of each harvest, and storage duration had significantly different content of total phenols (). At the first harvest, the minimum value was after 30 weeks of storage and maximum at harvest. At the second and third harvest time, the amount of total phenols decreased during the storage. It is in accordance with results of Piretti, Gallerani, and Pratella (Citation1994). However, as result of the decomposition of tannin compounds, total phenol content could be increased during storage as reported by Leja et al. (Citation2003).
Like the total phenols compounds, non-flavonoid phenolic fraction showed significant difference at each harvest time (). A similar trend was observed at each harvest with the maximum value at harvest and the minimum after 30 weeks of storage. The highest value of non-flavonoids was observed immediately after harvest in the third harvest (59.7 mg kg−1), but it seems that they rapidly decreased during storage in comparison with the first two harvests.
Awad and de Jager (Citation2003) observed different trends of total phenols during storage than other authors have confirmed. Kolesnik, Elizarova, Starodubsteva, Afanasyeva, and Erokhina (Citation1977) affirmed an increase of total phenols, whereas Piretti et al. (Citation1994) affirmed a decrease, and Ju, Yuan, Liu, Zhan, and Wang (Citation1996) found no changes in the amount of total phenols during storage.
Color parameters have been listed in . Like other fruit parameters, they also exhibit significant difference influenced by harvest time and the storage duration of apples – except fruit chroma which had significantly changed only during storage.
Table 3. Effects of harvest time and sampling time on apple fruit (cv. “Cripps Pink”) color parameters.
Tabla 3. Efectos del tiempo de cosecha y tiempo de muestreo en los parámetros de color de la manzana (cv. Cripps Pink).
Apples of each harvest, as well as for each storage duration showed significantly different lightness; so, the maximal value was after 14 weeks, and then it decreased after 30 weeks of storage.
Like the lightness, fruit chroma varied significantly only in storage duration (), without influence of harvest time. The value was increasing during 14 weeks of storage life, which was confirmed by Echeverría et al. (Citation2004). After 30 weeks of storage, C value was decreased.
Table 4. Effects of harvest time and storage duration on apple fruit (cv. “Cripps Pink”) weight loss calculated after storage and shelf life.
Tabla 4. Efectos del tiempo de cosecha y duración en almacenamiento en la pérdida de peso calculado después de la vida de almacenamiento y de estante de la manzana (cv. Cripps Pink).
In the third harvest, fruits had significantly lower value of the hue angle in relation to the first harvest. After 14 weeks of storage, the hue angle reached the highest value (80.4) and on further storage it decreased and hence, after 30 weeks, the hue angle had the lowest value (70.3).
Weight loss after storage at each harvest time, showed significant differences depending on the sampling ().
The fruit weight loss after the shelf life was not significantly influenced by harvest time or storage duration, Also, interaction between these two factors and the respective fruit weight loss was not significant.
Significantly greater fruit weight loss was observed after 30 weeks of storage (3.19%) in comparison with weight loss after 14 weeks of storage (2.05%); however, at the beginning of storage (first 14 weeks) fruit weight loss was almost doubled compared to fruit in storage in the rest of the storage time (15–30th week) when fruits lost only 1.14% of their weight.
Conclusion
The harvest time showed significant effect on all observed parameters except the fruit firmness, acids, fruit chroma, and weight loss (after storage and after shelf life). The lowest differences among the majority of all measured fruit parameters were noticed in the third harvest time and after 30 weeks of storage. “Cripps Pink” apple cultivar fruits harvested in the third harvest time preserved satisfactory quality without increasing the physical disorder incidences. On the other hand, the first and the second harvest time were not appropriate for the long-term storage of apple fruits. The storage duration significantly influenced every parameter except TSS, dry matter, and weight loss after shelf life. Results show that the storage life and harvest time significantly affected the majority of ripeness parameters. However, it seems that is not possible to determine optimal harvest time and storage duration based on one or two parameters of ripeness. This research reveals a strong influence of harvest time and storage duration, as well as their interaction, on “Cripps Pink” apple cultivar fruits quality.
Related Research Data
References
- Aaby , K. , Haffner , K. and Skrede , G. 2001 . Aroma quality of gravenstein apples influenced by regular and controlled atmosphere storage . Lebensmittel-Wissenschaft und-Technologie , 35 : 254 – 259 .
- Awad , M. A. and de Jager , A. 2003 . Influences of air and controlled atmosphere storage on the concentration of potentially healthful phenolics in apples and other fruits . Postharvest Biology and Technology , 27 : 53 – 58 .
- Brady , C. J. 1987 . Fruit Ripening . Annual Review of Plant Physiology , 38 : 155 – 177 .
- Brown , D. S. , Buchanan , J. R. and Hicks , J. R. 1965 . Volatiles from apple fruits as related to variety, maturity, and ripeness . Proceedings of the American Society for Horticultural Science , 88 : 98 – 104 .
- Cocci , E. , Rocculi , P. , Romani , S. and Rosa , M. D. 2006 . Changes in nutritional properties of minimally processed apples during storage . Postharvest Biology and Technology , 39 : 265 – 271 .
- Delaporte , N. 1971 . Influence de la teneur en oxygène des atmosphères sur le taux d'acide ascorbique des pommes au cours de leur conservation . Lebensmittel-Wissenschaft und-Technologie , 4 : 106 – 112 .
- DeLong , J. M. , Prange , R. K. , Harrison , P. A. , Shofield , R. A. and De Ell , J. R. 1999 . Using the Streif index as a final harvest window for controlled-atmosphere storage of apples . HortScience , 34 ( 7 ) : 1251 – 1257 .
- Drake , S. R. and Eisele , T. A. 1997 . Quality of ‘Gala’ apples as influenced by harvest maturity, storage atmosphere and concomitant storage with ‘Bartlett’ pears . Journal of Food Quality , 20 : 41 – 51 .
- Duquea , P. , Barreiro , M. G. and Arrabac , J. D. 1999 . Respiratory metabolism during cold storage of apple fruit. I. Sucrose metabolism and glycolysis . Physiologia Plantarum , 107 : 14 – 23 .
- Echeverría , G. , Fuentes , T. , Graell , J. , Lara , I. and López , M. L. 2004 . Aroma volatile compounds of ‘Fuji’ apples in relation to harvest date and cold storage technology a comparison of two seasons . Postharvest Biology and Technology , 32 : 29 – 44 .
- Fellman , J. K. , Rudell , D. R. , Mattinson , D. S. and Mattheis , J. P. 2003 . Relationship of harvest maturity to flavor regeneration after CA storage of ‘Delicious’ apples . Postharvest Biology and Technology , 27 : 39 – 51 .
- Ju , Z. , Yuan , Y. , Liu , C. , Zhan , S. and Wang , M. 1996 . Relationships among simple phenol, flavonoid and anthocyanin in apple fruit peel at harvest and scald susceptibility . Postharvest Biology and Technology , 8 : 83 – 93 .
- Kolesnik , A. , Elizarova , L. G. , Starodubsteva , T. V. , Afanasyeva , V. S. and Erokhina , T. S. 1977 . Changes in polyphenols during storage of fruits and vegetables . Prikladnaia Biokhimiia i Mikrbiologiia , 13 : 333 – 339 .
- Leja , M. , Mareczeka , A. and Benb , J. 2003 . Antioxidant properties of two apple cultivars during long-term storage . Food Chemistry , 80 : 303 – 307 .
- López , M. L. , Villatoro , C. , Fuentes , T. , Graell , J. , Lara , I. and Echeverría , G. 2006 . Volatile compounds, quality parameters and consumer acceptance of ‘Pink Lady®’ apples stored in different conditions . Postharvest Biology and Technology , 43 : 55 – 66 .
- Mapson , L. W. 1970 . “ Vitamins in fruits ” . In The biochemistry of fruits and their products (Vol. 1, pp. 369–383) , Edited by: Hulme , A. C. Vol. 1 , 369 – 383 . London : Academic Press .
- Mattheis , J. P. , Fellman , J. K. , Chen , P. M. and Patterson , M. 1991 . Changes in headspace volatiles during physiological development of Bisbee Delicious apple fruit . Journal of Agricultural and Food Chemistry , 39 : 1903 – 1906 .
- Official Methods of Analysis of AOAC International . 1995 . AOAC International Washington, USA, Secs. 942.15
- Official Methods of Analysis of AOAC International . 2002 . AOAC International Washington, USA, Secs. 967.21
- Ough , C. S. and Amerine , M. A. 1998 . Methods for analysis of musts and wines , Washington : J. Wiley & Sons .
- Peirs , A. , Lammertyn , J. , Ooms , K. and Nicolaí , B. M. 2000 . Prediction of the optimal picking date of different apple cultivars by means of VIS:NIR-spectroscopy . Postharvest Biology and Technology , 21 : 189 – 199 .
- Piretti , M. V. , Gallerani , G. and Pratella , G. C. 1994 . Polyphenol fate and superficial scald in Apple . Postharvest Biology and Technology , 4 : 213 – 224 .
- Róth , E. , Berna , A. , Beullens , K. , Yarramraju , S. , Lammertyna , J. Schenk , A. 2007 . Postharvest quality of integrated and organically produced apple fruit . Postharvest Biology and Technology , 45 : 11 – 19 .
- Villatoro , C. , Altisent , R. , Echeverría , G. , Graell , J. , López , M. L. and Lara , I. 2008 . Changes in biosynthesis of aroma volatile compounds during on-tree maturation of ‘Pink Lady®’ apples . Postharvest Biology and Technology , 47 : 286 – 295 .
- SAS Institute Inc . 2004 . SAS/STAT® 9.1 user's guide , Cary, NC : SAS Institute Inc .
- Smith , S. M. 1984 . Improvement of aroma of ‘Cox's Orange Pippin’ apples stored in low oxygen atmospheres . Journal of Horticultural Science , 59 : 515 – 522 .
- Streif , J. 1996 . “ Optimum harvest date for different apple cultivar in the “Bodensee” area ” . In Determination and prediction of optimum harvest date of apples and pears. COST 94. The postharvest treatment of fruit and vegetables , Edited by: De Jager , A. , Johnson , D. and Hohn , E. 15 – 20 . Luxembourg : European Commission .