This study focuses on the evaluation of official methods for determining frying oil quality with the new spectrophotometric method. The performance of these methods was examined by usage intermittent deep fat frying of potato chips in sunflower oil for 40 hr. at five consecutive days (8 hr., daily). Chemical analysis is the most reliable way to measure decomposition compounds in frying oil. With the prolonged frying time the amount of total polar compounds (TPCs) rises steadily. It has been suggested that the determination of TPCs is the most reliable method for the measurement of oil deterioration during deep frying processes. Beside, other oil quality indices during 40 hr. of intermittent deep fat frying were analyzed by the official methods and/or by rapidly spectrophotometric absorbance methods. Principal component analysis and linear regression analysis were used in order to assess the obtained results. The results were used to calibrate this spectrophotometric absorbance method. There was a strong correlation (r = 0.999) between quick spectrophotometric absorbance values and TPCs content in the same set of oil samples. The equation for conversion of the spectrophotometric absorbance values to TPCs content is: Y =-57.0083 + 2.64X + 0.049 X 2. Consequently, spectrophotometric absorbance method was developed to assess deep fat frying oil quality. This study was conducted to examine the relationship of TPCs contents determined by spectrophotometric method with physical, chemical indices and sensory evaluation. TPCs content was found to be correlated with refractive index (r = 0.950), viscosity (r = 0.989), colour (r = 0.993), acid value (r-0.899), iodine number (r = 0.947), P-anisidine value (r = 0.987), TBA test (r = 0.875), oxidized fatty acids (OFAs) (r = 0.975). Also, TPCs content was correlated with flavour (r-0.752), greasiness (r-0.917), crispy texture (r =-0.559) and overall acceptability (r =-0.649).These results showed that the new spectrophotometric absorbance method of frying oil is a good, rapid, simple, convenient and reliable indicator during deep fat frying of sunflower oil tested.

This study evaluates the effect of supplementation with Moringa leaves powder (MLP) at the concentrations of 0.25% and 0.50% (w/v) as additional sources of prebiotics to produce healthier fermented quinoa products. The biological experiment was used to study the influence of feeding with these fermented quinoa products on the blood biochemical parameters in experimental rats. The results indicated that selected probiotics, including Lactobacillus plantaram ATCC 14917 and Lactobacillus delbrueckii subsp. bulgaricus EMCC 11102 showed good tolerances to high acidity (pH = 2 or pH = 3), bile salts (0.3% w/v) and NaCl (7.5% w/v) and exhibited notable sensitivity against many antibiotics. Moreover, quinoa products supplemented with MLP at a concentration of 0.50% and fermented by both probiotics exhibited the highest counts of probiotic bacteria (9.32 and 9.12 log cfu/g, respectively) and showed more survival of probiotics than quinoa fermented without MLP (p > 0.05) during storage period. Also, the adding of MLP at both levels increased antioxidant activity and total phenolic contents of fermented quinoa by both probiotics, and the highest level exhibited highest values. Interestingly, fermented quinoa containing higher concentration of MLP showed the higher activity in improving serum lipid profile of experimental rats.

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Fermentation of quinoa by probiotics provides higher nutritional value and can be considered as a significant source of bioactive compounds and alive probiotics for the human body. Moringa leaves powder (MLP) at the levels of 0.25 and 0.50% were used as an additional prebiotic source to supply quinoa fermentation by Lactobacillus plantaram ATCC 14917 and Lactobacillus delbrueckii ssp. Bulgaricus EMCC 11102 and produce healthier quinoa products. The results indicated that supplementation of fermented quinoa products with MLP at bath levels increased its contents of free phenolics and water extractable arabinoxylans as well as enhanced its antioxidant activity and phytate degradation. Fermented quinoa products with 0.50% MLP showed better chemical properties than fermented quinoa products with 0.25% MLP. Furthermore, supplementation of fermented quinoa products with MLP (0.50%) displayed positive effects on blood glucose levels of the experimental rats. Further studies are required on the test of more kinds of probiotics with different concentration of MLP in quinoa fermentation in the future.