Abstract: Deep-fat frying of foods is considered every where the world the most common unit operation used in food preparations. For decades consumers have desired deep-fat fried products because of their unique texture composition ranging from potato chips up to traditional of both chicken products and fried fish sticks. When food is fried in such heated oil many complex chemical reactions and physical properties of the oil beginning to degrade. Such degrade compounds divided into volatile and nonvolatile compounds which may be caused a harmful to human as well as experimental rats and have a nutritional defects as well as may be had a role to prevalence of cancers , toxicity and tumors among consumers from both frying oils and foods being fried.
The present investigation was performed to study of both chemical and physical qualities of used frying oil on bolti fish (Oreochromis niloticus) and increase oil stability by using blending technique as well as nutritional quality and sensory characteristics point of view.
Chemical and physical characteristics of both unused blend oil (palm oil + sunflower oil 1:1 w/w) and used in frying at different numbers of fryings were withdrawn at 0 , 1 , 5 , 10, 20 and 30 were investigated such as SFC% , induction period (oil stability) , melting point , viscosity , color , UV absorbance, peroxide value , free fatty acid, iodine value, TBA, TPC , fatty acid compositions and volatile compounds, these compounds may have adverse role to change the nutrition quality of both fryings oil and fried foods.
From these chemical and physical qualities can be elucidate predicting equation used to identify quality and safety from used frying oil at different time of frying.
The changes in proximate chemical compositions for produce edible portion of fried bolti fish such as moisture , oil uptake, ash content, protein ratio , minerals and other contaminates heavy metals , amino acids pattern, fatty acids composition of fish lipid and sensory evaluation were examined to elucidate effect of frying process on changes nutritional quality of food being fried.
Fifty young male Albino rats, divided into 5 groups of 10 rats each were fed on diet contained 10% of the oils either used for zero , 5 , 10 , 20 and 30 fryings of spiced and buttered bolti fish as main treatment up to 105 day. Recover treatment as second treatment at similar subscribed rats was carried out to investigate the role of diet containing 10% fresh corn oil to repair previous adverse after fed on used different fryings oil. The effects of both frying oils and recovered oils (corn oil) were investigated on the biochemical parameters (blood picture, liver functions, γ-GT, lipogram (LDL, cholesterol HDL and triglyceride, creatinine, total protein and tumor markers (α-Feto Protein)) as indicated from blood analysis of treated rats were examined throughout the scope of study.
The adverse effects of the unused and used frying oils as well as recovered oil were examined on the internal rats organ (liver , kidney and heart) , organs weight , growth rate and histopathological alteration on fed rats were also considered. Many histopathological alterations seen in liver , kidney and heart tissues of experimental rats fed on frying oils. The recovery treatment demonstrated that recovered oil (fresh corn oil) can repair reversible defects in organs from fed on frying oils up to 10 times fryings, meanwhile, an excessive used frying oils from 20 and 30 fryings , the organs have irreversible defects and the body can not able to repair these excessive defects.
Key words: γ-GT, Amino acid, Blending oil, Blood picture, Bolti fish , Chemical composition, Contaminants heavy metals, Fatty acids composition, Frying oils, Growth rate, Histopathology, Liver function, Lipogram, Nutritional quality , Oil stability , Organs weight, Palm oil , Physical quality, Recovery treatment, SFC%, Tumor markers, Volatile compounds, Sunflower oil,
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