Variation of Physicochemical, Nutrient, Polyphenols and Tannin Proprieties of Cashew Apple (Anacardium occidentale L.) Pulp During Fermentation

Cashew tree is cultivated in northern Côte d’Ivoire primarily for its nut, but also for its fruit. The fruit also includes an edible apple, but its consumption is limited due to its astringent taste and short shelf life. This study aims to evaluate variation of physicochemical, nutritional, polyphenols and tannins of cashew apples during natural fermentation. Physicochemical tests revealed a decrease of pH for yellow and red cashew apples from 5.15 to 3.54 and from 5.12 to 3.49, respectively, alongside a corresponding reduction in dry matter content from 15.60% to 6.03% and from 15.28% to 6.12%. Meanwhile, titratable acidity increased from 0.042 g/100 g and 0.371 g/100 g and from 0.048 to 0.377 g/100 g for yellow and red apples cashew apples respectively. Nutritional analysis of red and yellow cashew apples showed a decrease in refractometric dry extract from an average of 12°Brix to 3.22°Brix (corresponding to an alcohol content of 2.24% to 5.8%), as well as a decrease in total sugars from 29.54 g/100 g to 3.68 g/100 g. However, the protein content fell from an average of 26.11 g/100 g on first day to 14.29 g/100 g on fourth day, before rising again to 22.47 g/100 g. Polyphenols and tannins analysis during fermentation revealed a drop in total polyphenol content, from 538.mgEAG/100 g to 305.14 mgEAG/100 g and from 652.66 mgEAG/100 g to 350.23 mgEAG/100 g respectively for yellow and red cashew apple. Condensed tannin content was also a decrease from 15.15 mgEAT/100 g to 3.12 mgEAT/100 g, and from 15.95 mgEAT/100 g to 3.57 mgEAT/100 g, respectively for yellow and red cashew apples. The results of these investigations allow to conclude that cashew apples could be a suitable substrate for fermentation in order to produce chemicals of interest, such as organic acids and alcohols. In addition, fermentation could be reduce astringency of cashew apples. Future studies will involve isolating and identifying microorganisms responsible for the natural fermentation of cashew apples.