Sensory-directed flavor analysis of key odorants compounds development of French fries and oils in the break-in,optimum and degrading frying stage

The flavor is a decisive sensory characteristic that determines the popularity of French fries(FFs).During high-oleic rapeseed oil(RO)frying,the flavor development of FFs showed three noticeable stages including break-in(3.5%-7.5%of total polar compounds(TPC)),optimum(7.5%-22.18%of TPC),and degrading stages(above 22.18%of TPC).Further,in order to distinguish the key aroma compounds in each stage,the FFs prepared in RO at TPC of 3.5%(FF4),14.5%(FF15),and 26.96%(FF27)and their relevant oils(RO4,RO15,RO27)were selected for sensory-directed analysis.The results revealed that the FF4 had low contents of(E,E)-2,4-decadienal(deep-fried odor)which also caused lower sensory score in FF4 sample.The higher contents of(E,E)-2,4-decadienal in FF15 induced its higher deep-fried odor.The FF27 had higher hexanoic acid(sweaty odor),heptanoic acid,nonanoic acid,benzene acetaldehyde(stale odor),and trans-4,5-epoxy-(E)-2-decenal(metallic odor)compared with FF4 and FF15,thus leading to the undesirable flavor of FF27.Moreover,the decrease of 2,5-dimethylpyrazine and 2-ethyl-6-methyl-pyrazine in FF27 induced the lower roasty flavor,which may also lead to the decline of the sensory score.Similarly,the higher contents of(E)-2-undecenal,hexanoic acid,heptanoic acid,and nonanoic acid in RO27 lead to increase its rancid score and thus lower the sensory score.

Improving oxidative stability of soyabean oil by apple pomace extract during deep frying of french fries

Repetitive use of same oil for deep-frying over extended period results in the production of various harmful compounds thus posing a serious health threat to consumers.Apple pomace,a by-product of apple processing industry is considered a rich source of various bioactive compounds,thus would be of great interest to the frying industry.The aim of this study was to explore the effect of apple pomace extract(APE)on the oxidative stability of soyabean oil during deep frying of french fries and compare it with its highest polyphenolic fraction quercetin(QE)and synthetic antioxidant tertiary butyl hydroquinone(TBHQ).Total phenols(TP)and Total flavonoid content(TFC)of APE obtained from ultrasound assisted extraction(UAE)was found to be(5.58±0.27 mg GAE/g)and(5.42±0.45 mg QE/g)respectively with an antioxidant activity of 76%and(9.9 mM As acid/mg)as determined by DPPH and FRAP assay.Soyabean oil enriched with natural antioxidants show higher thermal stability and quality in terms of various physico-chemical indices and sensory evaluation as compared to control and TBHQ enriched oils.Transfatty acids(TFA)in both control and antioxidant enriched oils during frying were found in higher concentration crossing the legal limit of 2%.The thermal stability of oils conferred by antioxidants follows this order QE˃APE˃TBHQ˃Control.Thus,natural antioxidants obtained from agro-industrial waste have the great potential to replace synthetic antioxidants effectively in conferring stability to deep-fried oils.