INFLUENCE OF FATTY MATTERS STABILITY ON SHELF LIFE AND QUALITY OF CRUNCHY TOAST

Abstract

Vegetable oils are found in three major classes in the market; soft (liquid) oils, hard oils (shortening) and margarine that differ in their blends, physical and chemical properties. Sunflower oil, palm oil shortening, partially hydrogenated soybean oil (HSBO) and soft margarine were used to represent these classes in this study. Crunchy toast recipes (high fat roasted pan bread) were prepared using different ratios of these fatty matters (5,10,15,20 and 25% flour basis) and applying different heat treatments in roasting process (110o C/hr, 140o C/25 min and 170o C/15 min). The partially hydrogenated soy oil (HSBO) showed the best stability and longest product shelf life, where sunflower oil was the lowest stability and worst product shelf life, that is indicated by stability chemical indices (peroxide value, free fatty acid, acid value, iodine value and TBA value) and storage tolerance. Not only the fat type influenced the shelf life but also the ratio of this fat. Moreover, the heat treatment clearly affect the stability and shelf life of the crunchy toast where the highest adding ratio and heat treatment the lowest stability and shelf life of products. Adding 1.5% of crushed herbs seeds (cumin, fennel and blackseed) enhances obviously the stability of oil and shelf life of product