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The efficacy of cellulose paper consolidated with cellulose acetate and mixed adsorbents (bentonite: activated clay: celite = 37.5: 50: 12.5 g with 1 g citric acid/100 g mixed adsorbents) on the physico-chemical properties of oil was evaluated during deep-fat frying of chicken nuggets for 7 days. Cellulose fiber and cellulose acetate were produced from waxy corn husks. Using adsorbents supported on cellulose fiber with or without cellulose acetate resulted in lower poly-unsaturated fatty acids (PUFAs), trans-fatty acid, free fatty acid (FFA), peroxide value (PV), and total polar materials (TPMs) compared with results from commercial filter paper (control). The L*, a*, and b* changes of treated oils were better than in control. Limiting the polarity in cellulose acetate might influence TPMs reduction but was more effective in overall quality improvement. The PUFAs, total trans-fatty acid, FFA, PV, and TPMs decreased by 1.8, 7.4, 37.0, 133.3, and 20.5%, respectively when compared with control. Therefore, the use of cellulose paper and cellulose acetate obtained from corn husks was found to significantly lengthen the life cycle of frying oil.

The physico-chemical and microstructural properties of fried rice crackers were studied as a function of spray-frying. Fried rice crackers were produced using the spray- and deep-frying techniques and their moisture content, oil uptake, color, texture (i.e., hardness, expansion ratio, and bulk density), and microstructure were compared. For spray-frying, the heat distribution inside the frying chamber, the effects of spraying rate of oil (0.3, 0.5, and 0.7 L/s), and spinning speed of the frying basket (60, 80, and 100 rpm) were evaluated. Although the average temperature varied at each depth of the fryer, it did not influence overall heat distribution. Results also revealed that higher spraying rate and spinning speed resulted in higher moisture loss, higher oil uptake, darker color, and less crispiness. Compared with deep-frying, the oil uptake of spray-fried samples was lower by 45.4%. The color of the spray-fried crackers was better than that of the deep-fried samples. SEM micrographs showed that the cellular structure and integrity of the cell wall of deep-fried rice crackers were more deformed. They also had larger pore diameter and deeper and larger cavities, leading to higher oil content and crispier texture than spray-fried samples. Rice crackers fried using a spraying rate of 0.7 L/s and spinning speed of 100 rpm resulted in the most desirable physico-chemical qualities. Although the texture properties of the resulting rice crackers could still be improved, spray-frying could be an alternative technique in producing high-quality rice crackers with very low oil content.

Chemosensory systems are currently being introduced in the food industries for quality control and process monitoring. This study was conducted to determine the possibility of using a chemosensory system to differentiate among varying intensities of oil rancidity and investigate discrimination between good, marginal and unacceptable frying oils. Fresh, 1-day, 2-day used and discarded frying oils were obtained from a fast food restaurant in each frying cycle for 4 weeks. The oil samples were analysed using a quartz-microbalance-based chemosensory system. The discrimination between good, marginal and unacceptable frying oils with regard to rancidity was examined and the results were compared to their physico-chemical properties such as dielectric constant, peroxide value, and free fatty acid content. The different qualities of frying oils were successfully evaluated and discriminated using the chemosensory system. Good correlations (r from 0.87 to 0.96) were found between changes in physico-chemical properties of oil and the sensor signals.

The possibility of using the whole spectra (wave numbers between 4000 and 850 cm −1 ) from Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) to differentiate between good, marginal and unacceptable oils with regard to various intensities of oil rancidity was investigated. Fresh, used, and discarded oils were collected from several fast food restaurants from each frying cycle for 4 weeks. Dielectric constant, peroxide value, free fatty acid content, and density of oil samples significantly ( P r ) between FTIR absorbance at 3300 cm −1 and free fatty acid content was from 0.84 to 0.94 for oils from the three restaurants. Similarly, the correlation between FTIR absorbance at 3471 cm −1 and peroxide value was from 0.90 to 0.97. The results of principal component analysis using the whole spectra (4000–850 cm −1 ) showed good discrimination and stability for identification between acceptable, marginal and unacceptable frying oils.