INFLUENСE OF SEASONAL FACTOR ON THE CHEMICAL COMPOSITION OF PERSIMMON
Persimmon is one of the most popular and favorite fruits not only in Georgia, but also in other countries. People love it for its unique specific taste and high nutritional value. There are more than 500 types of persimmon, properties and tastes which depend on the persimmon growing conditions.
The purpose of this project was to study the persimmon fruit chemical composition, the regularity in the quantity changes of the bioactive substances and technical-economical persimmon parameters during its storage and technological processing; to develop a highly profitable and efficient composite production technology for a new assortment of products and high quality beverages. Organoleptic and chemical tests of 12 persimmon fruit varieties were made. The content and composition of sugars, polyphenols, pectin, and tanning substances, were defined; and the relation of these parameters to the fruit maturity degree, the dynamics of their change in the ripening and storage process were determined. In addition, we determined the content of sugars ( inverted, total, saccharose), tanning substances (free, total), polyphenols and nitrogen through a spectrophotometric method, dry solids through a refractometric method, pectin (total, soluble, protopectin) and acidity through a potentiometric method, and cellulose through a chlorite method. The feasibility of the persimmon fruit industrial processing was established. Persimmon fruit of Khachia and Khiakume varieties were proved to be the best raw material for the industrial production of a fruit alcohol and beverages. It should be noted here that persimmon fruit must be harvested in November when they have a dark orange colouring and their dry solids content reaches 18%, inverted sugars make up 16-16.5%, and the acidity is 0.12%. For concentrate production, persimmon must be harvested in October when the fruit are yellow and their tanning and colouring substances reach 1.24%, and pectin substances make up 0.77%. The fruit sugars are glucose and fructose, generally in equal quantities. Tanning substances, leicoantocianes, in particular, are responsible for the tart taste; the lower their content is, the less the tart taste is felt, moreover, ripe fruit are less tart in flavour which is due to the tanning substances getting bound with high molecular substances. All the 12 persimmon varieties cultivated in Georgia can be used as raw material, including substandard and overripe fruit that are not marketable and do not have a long shelf life.
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