Introduction

Apple (Malus domestica Borkh.) is an economically important fruit crop of the temperate zones. It has been cultivated for thousands of years in Europe and Asia. There are more than 7 500 cultivars of apple and it is one of the most grown fruit in all over the world (Martinelli et al., 2008). Consumption of apple has shown better health to prevent a variety of chronic diseases and lung cancer, asthma, diabetes and ischemic heart disease (Hansen et al., 2009). It is due to the large content of structural cell walls and polysaccharides along with the various phyto-chemical antioxidants (Device et al., 2010). Apple is a leading deciduous fruit grown successfully in rain shadow or low rainfall high hill areas from east to far west of Nepal. Red delicious, Royal delicious and Golden delicious are the leading commercial cultivars grown by the farmers. In Nepal, apple can be grown in 54 districts; however, only 12 districts grow apple commercially of which Jumla ranks the number one in terms of area and production (Subedi et al., 2012). Apple farming is the boon of the farmers of Jumla because of its economical, social, and environmental advantages. Apple growers have not been receiving anticipated level of income because of traditional system of postharvest handling. In Nepal, the productive area, production and productivity of apple in F.Y. 2013/2014 was 5 141 ha, 35 920.7 tons and 6.9 tons/ha respectively. Nepal imports 56 447tons of apple annually valued at Rs 1.92 billion (ABPSD, 2014). In Nepal, large amount of fruit losses occurs after harvest and minimizing this loss could save over 25% of produce (Gurung, 1998). Gautam et al. (2004) reported that 58.2% apple fruits were damaged during harvesting, handling, transportation and distribution due to inadequate post harvest technology. All the apple production area lies in higher hills, where usually the fruits are harvested from the orchard and transported to farmhouse for sorting, grading and packaging. Conical shaped traditional bamboo baskets (Doko) are commonly used containers to carry apple fruits for transportation to collection centers by porters on their back. Fruits bruise easily due to compression, impact and vibration forces during transportation that potentially lead to bruising damage. Rough surface of the bamboo basket causes bruising and scaring on the surface of fruit. Further, the sharp edge of the basket and its conical shape causes both bruising and compression damage to the fruits. Moreover, the conical shape of bamboo basket results compression damage, which lies towards the lower side of the basket. The damage may not be apparent and visible to naked eyes immediately after transport; however effects are apparent during storage. The storability of apple is the reflection of the impact of container and cushioning material during transportation. Therefore, this study was carried out to find the effectiveness of different cushioning material for minimization of fruit damage during transportation from orchard to collection centre on standard apple cultivars.  In Kenya, less than 30% of the smallholder farmers in high potential areas use fertilizers while in low potential areas fertilizer use is less than 20% (Onyango, 2009). The low fertilizer use by the small-scale farmers can be attributed to lack of know-how and inability to afford the input. The Kenyan government has been promoting fertilizer use by small farmers through availing fertilizer at subsidized prices. For example, 50 kg of subsidized DAP is available at KSh. 2 500 (~25 USD) while private traders sell at between KSh. 3 500 (~35 USD) and KSh. 3 700 (~37 USD). The subsidized fertilizer can only be purchased from the National Cereals and Produce Board (NCPB) which is a local public institution. However, NCPB stores are far apart and farmers have to travel long distances; this discourages many small scale farmers from accessing this fertilizer and, left with no option, they buy expensive fertilizer from the local retail outlets. Due to the high cost of fertilizer from the private traders, farmers end up buying and applying less than the recommended fertilizer rates. Of all fertilizer used in Kenya, 51.7% goes to cereals, 17% goes to tea, 3.4 goes to coffee, 6.8% to special crops including flowers and 21.1% to all other crops (Sikobe, 2009). Among food crops, policy makers have put a lot of emphasis on maize (Sikobe, 2009; Ariga and Jayne, 2010) probably because it is the major staple food crop in Kenya. Interestingly, fertilizer use in potatoes is low despite the crop an important security food crop (FAO, 2013). There has been a general decline in potato production in Kenya (Gregory et al., 2013) because of a number of constraints among them low soil fertility (FAO, 2013). In addition, fertilizers are usually applied below the recommended rate (90 kg N ha_^-1+230 kg P₂O₅ ha_^-1) for potato production in Kenya (Kaguongo et al., 2008).

 

1 Materials and Methods

Studies were carried out for three successive years (2012-2014) at Horticulture Research Station, Rajikot, Jumla, Nepal (2 390 m a.s.l., 290 17’N, 82013’E) to investigate the effect of different cushioning materials on bruising damage of fruits during transportation from orchard to collection centre and thereafter on storage. Fruits of Red delicious, Royal delicious and Golden delicious were harvested on 3rd week of September from the Mother Stock Maintenance Block of Gairagaun, Jumla (2.8 miles). Fruits were harvested from all sides of the tree and healthy fruits of almost uniform size, color and shape were selected for the study. Fruits were thoroughly cleaned with Muslin cloth after harvesting. Study was designed as factorial RCBD (3 cultivars, 5 cushioning materials) with four replications. About 25 kg fruits were weighted and packed in conical shaped bamboo baskets with green grass (2” thick), woolen shawl, news paper, plastic foil (0.08 mm thick) and without liner. Baskets were transported to collection centre by porters on their back. Data on number of damaged fruits due to bruising was recorded one day after transportation, as the damage may not be seen immediately after transport. Again, undamaged 20 fruits from each replicate were selected and stored under room condition for 3 months (11.80C and 65% RH) to find out effect of cushioning materials and variation in cultivars. Observations were made on physiological weight loss and spoilage after storage. Consumer’s acceptability (Juyun Lim, 2011) was recorded by a panel of five judges on the basis of Hedonic ratting (1 to 9 scales in which 9 stands for like extremely and 1 stands for dislike extremely). Firmness of fruit was measured with hand Penetrometer (FT-327, Italy) having plunger diameter of 11 mm. TSS was recorded with hand Refractometer (Erma, Japan) calibrated at 20°C. Titratable acidity was determined by titrating a 5 ml juice with 0.1 N NaOH using Phenolphthalein as an indicator (AOAC, 1990). Starch Iodine test was carried out to determine the conversion pattern of starch into sugars (Reid et al., 1982). Iodine solution was prepared by dissolving 10 grams of iodine crystals and 25 grams of Potassium Iodide in 1 liter of water. Fruits (N=10) were cut at right angles to the core, approximately halfway from stem to calyx end; Iodine solution was applied to cut surface, drained away any excess and rated fruit staining after 2 minutes by using 0 to 6 scales (0 stands for full starch and 6 stands for free of starch). Observations were made for various physiochemical characteristics and quality attributes. Data were analyzed statistically using GenStat software version 10.3 (VSN International Ltd. Rothamsted Experimental Station, 2011).

 

2 Results and Discussion

2.1 Number of Bruised Fruits (%)

Number of bruised fruits after transportation was highly significant among apple cultivars. Maximum number of bruised fruits was observed in Golden delicious (20.3%) followed by Royal delicious (17.3%) while minimum (13.3%) in Red delicious (Table 1). Likewise, maximum number of bruised fruits (24.0%) was observed in bamboo basket without liner followed by plastic liner (19.0%) while minimum (11.3%) in grass liner (Table 2). Interaction effect of cushioning materials with cultivars on brushing was lowest in grass cushion followed by woolen shawl while highest in ordinary bamboo basket without cushion (Table 3). Different cultivars of apple may have differential tolerance to bruising and compression damages based on the nature of fruits such as skin thickness and texture. Apples bruise easily due to compression, impact and vibration forces (Gautam, 2004). Compression damage may occur in lower depth of the basket as a result of load of upper fruits, while impact damage may occur due to rough handling on the surface of fruit. Vibration forces usually occur during transportation, are difficult to avoid. These damages could be minimized if common sense is used for understanding of appropriate transportation system, packaging design and post harvest handling. This study also found the highest bruising damage on Golden delicious cultivar similar to the study conducted by Timm et al. (1989). The highest bruising damage on bamboo basket without liner obtained from this study is also supported by the finding by Gautam et al. (2004) and Shrestha (1996).

 

 

2.2 Physiological Weight Loss (%)

Physiological Weight Loss (PWL) during storage was highly significant among apple cultivars (Table 1). Maximum PWL was observed in Golden delicious (17.2%) followed by Royal delicious (14.3%) while minimum in Red delicious (11.4%) after storage. Maximum PWL in Golden delicious might be due to thin peel (58.7 μm) resulting more water loss due to higher evapo-transpiration and respiration (Homutová et al., 2004). Chaudhary et al. (2004) reported that apple fruits stored for six month under normal room condition observed lowest PWL in paper cushion in wooden boxes (47.6%) while maximum in floor storage (88%). Water loss among apple cultivars during storage varied resulting in significantly different weight loss even under similar storage conditions (Khan et al., 2005). Saleh et al. (2009) reported that fruits of Golden delicious, and Gala stored at 90% RH and 0°C for 180 days exhibited significant differences in physiological and anatomical parameters. Physical properties of fruit may also have significant influence on storage performance because it influences water loss, gas exchange and subsequent storage life (Meisami et al., 2009). Differences in storage performance may be due to ethylene production, responsible for the changes in texture, firmness and fruit softening (Khan et al., 2005).

 

2.3 Spoilage (%)

Spoilage loss during storage was highly significant among apple cultivars with and without cushioning materials. After three months of storage, maximum spoilage was observed in Golden delicious (16.8%) followed by Royal delicious (13.1%) while minimum (10.1%) in Red delicious (Table 1). Likewise, maximum spoilage (24.3%) was observed in fruits transported in ordinary bamboo basket without liner followed by plastic liner (14.4%) while minimum (7.2%) in grass liner (Table 2). Interaction effect of cushioning materials with cultivar during storage was lowest in grass cushion followed by woolen shawl while highest in ordinary bamboo basket without cushion (Table 3). The result indicates that different cultivars of apple have differential tolerance to bruising and compression damages based on the nature of fruits such as skin thickness and texture. Higher spoilage damage on Golden delicious might be due presence of thin peel thickness and soft texture, probability of damage to internal tissue by compression, impact and vibration forces is high during transportation, resulting more spoilage loss during storage. Paudyal et al. (2016) reported that maximum spoilage (32.5%) was observed on control while minimum (17.5%) on paper wrapped apple fruits after 60 days of storage. The scratches or minor wounds may not be apparently visible right after transportation however it has significant influence during storage.

 

2.4 Sensory evaluation

At maturity stage, overall acceptability was higher in Royal delicious (8.8) followed by Red delicious (8.7) while lower in Golden delicious (7.9). Red delicious maintained higher sensory score (4.8) while lower in Royal delicious & Golden delicious (4.4) after storage (Figure 1E). Retention of better firmness, aroma, taste and crispiness was higher in Golden delicious after storage, however, showed unacceptable appearance due to more shriveled texture. Mann et al. (2005) reported that the sensory attributes that fruit texture include firmness, crispness, mealiness and juiciness.

 

2.5 Fruit Firmness

At maturity stage, a significantly higher fruit firmness was recorded in Golden delicious (9.1 kg/cm_²) followed by Red delicious (8.1 kg/cm_²) while lower (7.2 kg/cm_²) in Royal delicious (Figure 2A). Firmness of apple fruits decreased after storage. Highest firmness was recorded in Golden delicious (5.9 kg/cm_²) followed by Red delicious (4.8 kg/cm_²) while lowest in Royal delicious (3.8 kg/cm_²). This evidence indicates that Golden delicious still has retained turgidity of the cells as compared to other cultivars. The softening of flesh during storage could be due to the degradation of soluble pectin by high activity of endo-poly-galacturonase enzyme in fruits (Mann et al., 1990). Apple fruit texture and flavor are important traits that guide consumer preference (Daillant-Spinnler et al., 1996). Apples that have crisp, juicy texture and prolong postharvest life are highly favored by the consumers (Jaeger et al., 1998).

 

2.6 Juice content (%)

At maturity stage, a slightly variation on juice content was noticed with respect to apple cultivars. Highest juice content was recorded in Golden delicious (73.9%) followed by Red delicious (70.1%) while lower (70.0%) in Royal delicious (Figure 2B). Juice content of apples decreased after storage. After three months of storage, the juice content was 41% in Golden delicious followed by Red delicious (35.0%) and lowest in Royal delicious (33.5%).The loss of juice percent during storage was higher in Royal delicious (57.4%) followed by Red delicious (52.1%) while lower in Golden delicious (44.5%). More juice loss percent on Royal delicious might be due to over ripening resulting mealiness and softening of fruits.

 

2.7 Total Soluble Solids (⁰Brix)

At maturity stage, highest TSS was noticed in Golden delicious (12.7) followed by Royal delicious (10.7) and lowest (10.5) in Red delicious (Figure 2C). TSS of apples increased during storage. Highest TSS was noticed in Golden delicious (14.6) followed by Royal delicious (14.3) and lowest (13.7) in Red delicious. TSS of apple is a major quality parameter which is correlated with texture and composition. Increase in TSS could be attributed to breakdown of starch into sugars or hydrolysis of cell wall polysaccharides (Weibel et al., 2004).

 

2.8 Titrable Acidity (%)

At maturity stage, highest Titrable Acidity (TA) was recorded in Golden delicious (0.32%) followed by Red delicious (0.24%) and lowest (0.23%) in Royal delicious (Figure 2D). The level of TA decreased during storage. Highest acidity was recorded in Golden delicious (0.23%) followed by Red delicious (0.19%) while lowest in Royal delicious (0.17%) after storage. Malic acid is the major acid in apple juice plays a major role in flavor attribute (Ben et al., 1985). Reduction of TA during storage might be due to conversion of organic acid into reducing sugars during ripening of fruit.

 

2.9 TSS: TA ratio

At maturity stage, highest TSS: TA ratio was recorded in Royal delicious (47.6%) followed by Red delicious (43.8%) and lower (39.6%) in Golden delicious. The level of TSS: TA ratio increased after storage. Higher TSS: TA ratio was recorded in Royal delicious (86.4) followed by Red delicious (73.8) while lower (63.6) in Golden delicious (Figure 2E). This might be due to conversion of acid into sugars. Excessive increase in TSS: TA ratio in Royal delicious caused imbalance resulting poor sensory rating due to development of slight bitterness and mealiness. Mahajan (1994) reported that many biochemical changes take place during storage which disturbs the TSS: TA ratio ultimately rendering the fruit unacceptable.

 

2.10 Starch index

At maturity stage, higher starch index was recorded in Royal delicious (4.9) followed by Red delicious (4.3) while lower (3.9) in Golden delicious (Figure 2F). The level of starch decreased after storage. Higher starch index was recorded in Royal delicious & Red delicious (6.0) while lower in Golden delicious (5.6). This might be due to conversion of starch into reducing sugars during ripening of fruits. Saleh et al. (2009) reported that fruits stored at 90% RH and 0ºC for 6 months exhibited significant differences in physiological and anatomical parameters may be due to ethylene production, responsible for the changes in texture, firmness and fruit softening.

 

3 Conclusion

Among the cultivars evaluated, Red delicious cultivar fruits had minimum level of damage during transportation, less PWL, lesser spoilage, prolonged shelf life and higher sensory rating during storage which was followed by Royal delicious. Besides having prolonged shelf life for Golden delicious fruits, they were less preferred by the consumers as because of its poor physical appearance, sensitivity to damage during transportation and storage due to thin peel and soft texture. For transportation of fruits from field to collection center in conical bamboo basket, lining with grass or woolen shawl was found most efficacious, low cost and easily available lining materials to reduce scratching damage.

 

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