The aim of the present study was to evaluate the effect of chicken nuggets addition on the degradation of canola oil during frying compared to the changes occurring when the same frying medium was simply heated at frying temperature as control. Heating or frying test was carried out at 185±5oC using electric fryer for 8 h/day for 3 consecutive days and the oil sample was collected every 4 h. The changes in fatty acids composition and physicochemical properties of the oil samples during frying and controlled heating experiments were monitored. In this study, refractive index, free fatty acid content, peroxide value, p-anisidine value, polar compounds and viscosity of the oils all increased, whereas iodine value and C18:2/C16:0 ratio decreased as heating or frying progressed. The percentage of linoleic acid tended to decrease, whereas the percentages of palmitic acid increased. Gas chromatography analysis revealed that adding chicken nuggets to heated canola oil led to higher decrease in the ratio of C18.2/C16:0 compared to what was measured when the fat alone was heated at frying temperature. The presence of chicken nuggets accelerates the formation of polymerization products and polar compounds in canola oil during frying.
Guava (Psidium guajava L.) is a rich source of vitamin C (ascorbic acid) having high water
content (above 80%) which makes it extremely perishable, but storage, handling, processing
and transporting becomes difficult due to high moisture content. Therefore, guava needs
dehydration process by upholding its natural colour and minimum ascorbic acid losses. We
have carried out a comprehensive study to examine the influence of different drying treatments;
under direct sunlight, freezing, convection oven (50, 60, 70, 80 and 90°C) and microwave
oven (100, 250, 440, 600 and 1000 watts) on ascorbic acid concentration and colour quality
of guava. The mean values of ascorbic acid concentration of dried guava slices were changed
significantly (P < 0.05) as compared to fresh guava slices. The colour of guava slices became
yellowish with an increase in temperature and power of conventional and microwave ovens,
respectively. We found freeze drying as the best method for the dehydration of guava in terms
of ascorbic acid and natural colour preservation.