EFFECT OF PASTEURIZATION AND STORGE ON FLAVOUR OF APPLE AND KIWIFRUIT BLEND JUICE

Abstract

A blend Juice prepared from apple juice and kiwifruit juice (60:40 v/v), was pas-teurized and stored for 3 and 6 months at 4o and 25oC untill analysis. Sensory evalu-ation showed significant differences between the fresh and pasteurized blend juice in all sensory attributes. The headspace volatiles of fresh apple, fresh kiwifruit, fresh and stored pasteurized blend juice at different temperatures were collected and sub-jected to GC and GC-MS analysis. A total of 33 volatile components were identi-fied, 18 esters (17 aliphatic and one aromatic), 6 alcohols, 3 aldehydes, 3 terpenic hydrocarbons, 2 ketones and 1 carboxylic acid. The volatile components in the pas-teurized blend juice showed considerable quantitative and qualitative variations dur-ing storage. By comparative study between the blend juice and fresh apple, fresh kiwifruit juices it was clear that the pasteurization process caused a remarkable in-crease in the total esters content due to the high increase in methyl propanoate, me-thyl butanoate and methyl benzoate. Pasteurization caused a sharp decrease in buta-nol which is the most abundant compound in fresh apple juice. All alcohols showed the same trend except ethanol. Pasteurization revealed a remarkable decrease in (E)–2-hexenal which is the most abundant compound in fresh kiwifruit juice. Regarding the effect of storage it was noted that the blend juice stored at 4oC showed high qual-ity after 3 months due to the remarkable increase in the contents of total ester, buta-nol, and (E) –2- hexenal with a decrease in limonene, but after 6 months the good quality was attributed to the high increase in ethyl butanoate concentration. While stroage at 25oC showed good quality after 3 months due to the very high increase in total esters content which attributed to a greate increase in ethyl butanoate concen-tration (which gave sweet and fruity aroma to juice), but storage for 6 months gave rise to a sharp decrease in ethyl butanoate which led to a high loss in aroma quality.