Study on preharvest factors affecting quality and postharvest characteristics of the banana fruit and alleviation of its chilling injury

Thesis (Ph. D. in Agricultural Science)--University of Tsukuba, (A), no. 4694, 2008.3.25Includes bibliographical references (leaves 131-150

Effect of Activebag® modified atmosphere packaging on the postharvest characteristics of mango fruits, Mangifera indica L, cultivar Tommy Atkins

Objective: This was to evaluate the efficacy of MAP in maintaining the postharvest quality of mango fruits.Methodology and results: The fruits were harvested from a commercial orchard, (Karurumo Orchards) located in Embu county of Eastern province. The fruits were harvested at advanced maturity during the pre-climacteric rise phase when most of the flesh had turned yellow. They were selected for uniformity in colour, size and shape and randomly separated into three equal batches of 50 fruits each. The first batch was packaged in Activebag®, second batch in ordinary (commercially used) polythene bags while the third batch was left unpackaged as control. Five fruits from each treatment were sampled every three days during the shelf life period and evaluated for various physiological and physicochemical parameters associated with mango ripening and quality including ethylene evolution, respiration rate, cumulative weight loss, firmness, hue angle, total soluble solids, total titratable acid, soluble sugars, ascorbic acid and beta-carotene. MAP whether in Activebag® or ordinary polythene was effective in maintaining the quality of mango fruits compared to the unpackaged controls. Slow ripening changes of Activebag® fruits was accompanied by a delayed respiratory climacteric and generally lower respiration rates compared to ordinary bag and unpackaged fruits. At the end of the observation period, Activebag® fruits were 16% firmer compared to unpackaged fruits. The initial average weight was 635g and modified atmosphere packaging had a remarkable effect on cumulative weight loss with fruits packaged in the ordinary polythene bag and Activebag® fruits losing only 7.4% of the initial weight compared to 12% in the case of unpackaged fruits (control). Higher levels of total soluble solids (°brix) 5.5g/100g and total soluble sugars (6g/100g) observed at the beginning of storage (6 days after packaging) signalled advanced ripening of unpackaged fruits. However as the storage time progressed, the levels of each of the soluble sugars evaluated were higher in Activebag® fruits. Similarly, Activebag® fruits retained higher levels of titratable acidity (0.39%and ascorbic acid compared to ordinary bag fruits (0.36%).Conclusion: Packaging mangoes in Activebag® after harvest at ripe stage was effective in delaying most of the ripening related changes in mango fruits thereby maintaining the quality and extending their shelf life. Although ordinary polythene packaging maintained quality of the fruits better than unpackaged fruits, the positive effects were negated by high incidences of rotting.Key words: Mango, MAP, postharvest, quality, shelf lif

The Effect of Different Waxing Technologies on Shelf Life of ‘Apple’ Mango Fruits Stored Under Different Storage Conditions

Beneficial effect of Shellac and Mango wax of different formulations was studied on shelf life of apple mango fruits which were harvested at mature green stage and stored in various storage conditions including ambient (25ºC) and simulated commercial cold storage (12ºC).  Mango wax (one mixed with a fungicide and another without) was obtained from United Phosphorous Limited, while Shellac wax was purchased from a commercial trader in flakes form and dissolved in 0.1N Sodium hydroxide to make two concentrations (3% and 5%). The two waxes were applied by dipping the fruits in a bowl of wax and placing them on wire mesh for air drying using fans. Upon drying the fruits were packed in open cotton boxes and stored in ambient (25ºC) and cold storage (12ºC). Three fruits from each treatment and different storage conditions were sampled after every 3 and 7 days (ambient and cold storage respectively) for measurement of attributes associated with ripening including weight loss, respiration rate, peel firmness and pulp hue angle.  Results indicated that waxing whether with Shellac or Mango wax was effective in extending shelf life of mango fruits for 4 and 6 more days in ambient and cold storage respectively. At the end of observation period, un waxed fruits in ambient and cold storage had lost 12.4% (day10) and 5.5% (day 22) compared to an average of 7.6% (day14) and 3.7% (day 28) for the waxed fruits respectively.  Waxed fruits exhibited low respiration peak of 49.39 and 30.38 ml/kg/hr compared to un waxed fruits that had a high peak of 85.09 and 43.15 ml/kg/hr for ambient and cold storage respectively signifying high respiratory activity in the un waxed fruits. Other ripening related parameters had a positive correlation to respiration and water loss. This study shows that coating of mango fruit with wax is effective in delaying ripening thereby extending its postharvest life. Keywords: Mango wax, Shellac wax, Shelf life, Mango, Postharvest technologies, Storag

Effects of mode and timing of calcium chloride application on tissue calcium concentration and acceptability of mango fruits

Mango (Mangifera indica L) production in Kenya directly supports approximately 200,000 farmers and many other beneficiaries. Despite this, its production suffers from post-harvest losses due to the fruits' short shelf life in ambient conditions. Calcium maintains cell integrity, strengthens the cell wall, membrane structure, and thus increases shelf life. A completely randomized block design with a split plot arrangement was used to compare the effect of spraying and immersion of ‘Van Dyke' mango fruits at maturity or 15 days later in calcium chloride at different concentrations (0.5%, 1%, 1.5%, or 0%) and times on the fruit ripening rate and organoleptic acceptance. The peel firmness (N), total soluble solids (0Brix), flesh color (Ho), beta carotene (mg/100ml), and carbon dioxide evolution (ml/kg/hr) of fruits were determined at time 0 and every two days for up to eight days in ambient conditions. Additionally, organoleptic characteristics, flesh firmness, calcium concentration (g/mg), and their correlations were determined. Fruits immersed in calcium chloride at maturity had higher retained peel firmness (10.6 N, 10.3 N), deeper flesh color (37.45, 36.78), lower total soluble solids (14, 13.8), a lower carbon dioxide evolution (30.7 ml/kg/hr), higher beta carotene and higher flesh calcium concentration than fruits exposed to other treatments. Fruits sprayed at maturity outperformed those sprayed 15 days later in the studied parameters. Flesh calcium content correlated positively with flesh firmness (r= 0.913, r= 0.852), flesh color (r= 0.828, r= 0.841), fruit aroma (r=0.8199, r=0.841), and negatively with skin shriveling (r=-0.778, r=-0.806) and fruit flavor (r=-0.811, r=-0.829). Flesh firmness correlated negatively with skin shriveling (r=-0.868, r=-0.788) and fruit flavor (r=-0.8869, r=-0.821), but positively with peel color (r=0.9115, r=0.856) and aroma (r=0.907, r=0.848). Skin shriveling was found to have a negative relationship with peel color (r=-0.944, r=-0.93) and aroma (r=-0.944, r=-0.938), but a positive relationship with fruit flavor (r=0.933, r=0.947). Peel color correlated positively with aroma (r=0.979, r=0.977) and negatively with fruit flavor (r=-0.962, r=-0.950), respectively. Despite the effectiveness of post-harvest calcium chloride immersion in extending fruit shelf life, optimal use is advised to avoid deteriorated pulp flavor and increased shriveling. More research is needed to determine how calcium chloride can be made available to the fruit while it is still attached to the tree

Can calcium sprays alleviate jelly seed in mango fruits?

Jelly seed is a major challenge in mango production leading to enormous losses in the value chain. This internal fruit disorder is characterised by disintegration of cells, consistency of jelly and broken cells. Calcium plays an important role in enhancing tissue stability and firmness thus reducing cell disintegration. A two-year field study was conducted in Embu County, Kenya using ‘Van Dyke’ cultivar trees of approximately 10 years old. The objective of the study was to investigate the effect of varied sources of calcium, applied at different rates and timing on jelly seed occurrence and tissue calcium distribution. Calcium  in the form of calcium chloride, calcium nitrate and  easygro®  were applied at 1.0%, 1.5%, 2.0% or 0% (control) at three stages of  fruit development  (fruit set, 30 days after fruit set and 30 days to anticipated physiological maturity). The experiment was set up in a randomised complete block design with a split-split arrangement replicated three times. Fruits were harvested at physiological maturity and ripened at ambient conditions (28±1̊C, 75-80 RH). Data collected included: jelly seed occurrence, calcium distribution (exocarp, mesocarp, endocarp and cotyledon) and fruit weight. Jelly seed occurrence and calcium distribution were determined at ripe stage. All the calcium sources invariably suppressed the occurrence of jelly seed. Calcium chloride (2.0%) applied at fruit set had the lowest average jelly seed score of 1.2 and 2 in seasons I and II respectively. There was a significant negative relationship between fruit weight (r = -0.55, r = -0.52), calcium content in the exocarp (r = -0.56, -0.49), mesocarp (r = -0.52,-0.76), endocarp (r= -0.76, -0.66) and jelly seed incidence occurrence. This suggested that calcium has a role in alleviating jelly seed disorder. Application of calcium at fruit set was more effective in suppressing jelly seed occurrence than later applications. Calcium chloride (2.0%) applied at fruit set was more effective in reducing jelly seed occurrence. There is need to study further on soil based calciumand other calcium formulations on the effects on jelly seed occurrence

Characterization of postharvest physiology attributes of six commercially grown tomato varieties in Kenya

Tomato (Lycopersicon esculentum Mill) is the leading vegetable in terms of production in Kenya. The Kenyan local market has a wide variety of tomato cultivars with a wide range of morphological and sensorial characteristics. However, information on the nutritional and postharvest quality of these varieties is lacking. The aim of this research was to investigate and identify tomato varieties of superior postharvest quality and recommend them to small and medium scale farmers. In this study, six tomato varieties were grown in a greenhouse and analyzed at three maturity stages (mature green, turning and red ripe). The tomatoes were analyzed at specific days after harvest and storage at room temperature (25o C). Percentage weight loss, color, respiration and ethylene production rates were analyzed to assess the postharvest quality of the tomatoes. The color was measured using a Minolta Chromameter while the respiration rate and ethylene production rates were determined using the static system approach. Color, weight loss, respiration and ethylene production rates were positively affected by storage time when harvested at the three maturity stages. The percentage weight loss of the tomato fruits was higher in the determinate varieties, and at the turning stage of maturity (3.8 %). Minor color changes were observed after storage of the tomatoes harvested at red stage for six days. Both rates of respiration and ethylene production were low, with the respiration rate ranging between 56-10 ml CO2 Kg-1h-1. The Chonto F1 variety had the highest rate of ethylene production (5.4 μL C2H4 Kg-1h-1) on the 4th day of storage after harvest at the red ripe stage. Overall, the indeterminate tomato varieties displayed better postharvest quality that can prolong the fruits shelf life for marketing. In turn, the turning stage of maturity proved to be a better stage to harvest tomatoes as the color development was more uniform.Keywords: Tomato, varieties, postharvest quality, respiration rate, ethylene, colo

Guiding Nutritious Food Choices and Diets along Food Systems

Poor diets are responsible for more of the global burden of disease than sex, drugs, alcohol, and tobacco combined. Without good health, food security, and nutrition, development is unsustainable. How food is grown, distributed, processed, marketed, and sold determines which foods are available, affordable, and acceptable within the local cultural context. These factors guide food choices, influencing the quality of people’s diets, and hence they play a vital part in health. The food system is complex and is neither nutrition nor health driven. Good nutrition and human health are not seen as important supply chain outcomes, diminishing between the different processes and actors in the chain. This is in contrast to the environmental and labour concerns now also perceived as supply chain issues. Although food loss and waste is now appreciated as key to sustainable food supply chains, the critical role on nutrition security remains obscure. In a free market dispensation, the trade-offs between agricultural production and income generation versus nutrient delivery from farm to fork needs to be addressed. Investment and incentivised initiatives are needed to foster diverse food production, preservation, distribution and influence consumers’ behaviour and consumption. The decisions made at any stage of the food supply chain have implications on consumer choices, dietary patterns, and nutritional outcomes. Leveraging the entire food system is an underused policy response to the growing problem of unhealthy diets