By Bilal Akram, Dr. Zahoor Hussain, Dr. Mujhaid Ali
Horticulture, University of Sargodha, Sargodha
Soft, delicate and delicious dessert quality fruit commonly known as Persimmon botanically called Diospyrus kaki belongs to family Ebenaceae. There are more than 200 species in genus Diospyrus. Persimmon originated in China and was introduced in Japan in 7th and in Europe in 17th century, grown also in Asia and South America. Botanically persimmon is a berry. Persimmons are considered a good source of readily available carbohydrates and a high content of bioactive compounds, such as tannins, polyphenols, steroids, dietary fiber, organic acids, minerals and carotenoids, which contribute to the high antioxidant potential. Fruit shape varies from spherical to acorn, to flattened or squarish, while its weight can go from 30 g to more than 450 g and it depends largely on variety and climatic conditions. Color of fruit varies with variety from yellow to dark red. Gaseous exchange in persimmon occurs through calyx. There are two groups astringent and non- astringent persimmons. Astringency of fruit is only due to high level of tannins in fruit.
Postharvest shelf life of persimmon is very short due to its thin skin which can be damaged during harvesting and postharvest handling operations. There is an overview of some important steps in postharvest handling of persimmons as follow:
Persimmons are harvested in autumn. Proper harvesting and handling is important for good quality and market acceptability. It is possible to snap fruits from trees, but this requires skill and increases its susceptibility to injury and subsequent decays. Generally, two to three picks are required depending on the cultivar and seasonal conditions. Fruits need to be well developed and to display the characteristic cultivar color before being harvested. Unlike other fruits soluble tannins contents are more important rather than total soluble solids as maturity indicator. Color maturity charts are useful in indicating maturity of fruit but charts are different for different cultivars. Biochemical parameters are more reliable than the color charts. The fruit must be handled very carefully to avoid bruising and injury.
Sorting& grading of fruits:
Prior to sorting and grading of fruits, fruits are washed with clean water to remove dust and disease causing agents. Diseased and injured fruits should be discarded. Fruits can be graded according to size and weight of fruit.
Packing is also an important factor that determine the shelf life of produce and market acceptability. Packaging material should be clean and according to demand of consumers. Packing should be done carefully and according to the distance of market. Packing should not be done beyond the capacity of package/ box. Proper packing material is used which make sure air movement during storage and transportation.
Temperature is an important factor in determining the shelf life of produce. During storage temperature of produce is of our concern rather than the temperature of storage room. Optimum temperature for storage of Astringent persimmons is -1 to 0°C and fruits can be stored for up to 4 months. The non-astringent persimmon can be stored at the temperature of 7°C but will keep up to 5 months if fruits are packed individually in polyethylene bags and held at 0°C.
Relative humidity is very important in extending shelf life of a persimmon. As persimmon is a climacteric fruit the rate of respiration can be controlled by providing optimum humidity. Persimmon should be stored at relative humidity of 90-95%.
Controlled Atmosphere Storage:
Shelf life of persimmons can be enhanced by storing them in controlled atmosphere storage room rather than stored in simple storage room. Fruits stored at optimum temperature, relative humidity and ethylene free air have short storage shelf life rather than the fruits stored at optimum temperature, humidity ethylene free air Controlled atmosphere (3-5%O+5-8% CO2).
Ethylene production and storage/transportation:
Persimmon fruits are most sensitive to ethylene action. It is big hindrance in long storage life of produce. It also increases the chance of disease incidence and cause decaying of fruits by making them soft. Ethylene removal and exclusion from the storage facility and transport can reduce the chance of decaying.
Persimmons fruits can be stored at low temperature but some cultivars like “Fuyu” shows chilling injury symptoms at low temperature. This injury cause deterioration of fruits and affect the market of fruit. Problem can be solved by avoiding the exposure of sensitive cultivars fruits to low temperature and by use of controlled atmosphere (3-5%O+5-8% CO2).
Alternaria rot caused by alteernaria altenata which attacks developing fruits. Infections remain quiescent until harvesting Black spots appear as the fruit ripens in store room. Wound infections results in early appearance of symptoms. Calyx Separation is a physiological disorder which may affect certain cultivars; it has caused losses in New Zealand. Growing conditions are all-important, and excessive nitrogen fertilization should be avoided. If the plants are thinned early in the season, this will enhance calyx growth and help to prevent the disorder.
Postharvest shelf life enhancing is of much importance to full fill the demands of day by the day increasing population. Main focus of the world is to ensure the availability of good quality and quantity of food to all people facing hunger. Good Post harvest handling operation/ practices are quite important in gaining good profit. All horticultural produces require much attention in postharvest handling due to their perishable nature.