Pre-treatments of Tas-A-Ganesh grape bunches and subsequent effect on their drying

The pre-treatment of Tas-A-Ganesh bunches affected the quality parameters of raisins when bunches were dried under raisin sheds. Various combinations of ethyl oleate and potassium carbonate affected the moisture content and other quality parameters of raisins. The dynamics of changes in content of moisture and colour intensity was also affected by pre-treatments. The contents of phenols, flavonols, flavonoids and flava-3-ols in the raisins were also significantly affected by the pretreatments. Application of 15 ml/l ethyl oleate and 25 g/l potassium carbonate for 2, 4 and 6 min. significantly affected the moisture content, colour intensity and content of other colour contributing substances, viz., phenols, flavonols, flavonoids and flavan-3-ols of raisins. Increment in pre-treatment duration resulted in early drying and raisins obtained had lower colour intensity. The best quality raisins (15.9%) were observed by pre-treatment of grape bunches with solution of 15 ml ethyl oleate and 30 g/l potassium carbonate.