Volume 18, Issue 5

Sample to oil ratio (SOR) during frying of food products should be carefully determined because it substantially influences oil absorption. A novel computer simulation to model momentum, heat, and mass transfer was developed to investigate the effect of SOR (1/10, 1/15, and 1/20) on velocity, temperature, moisture, and oil distributions during frying of potato strips. The present study was intended to cover missing aspects in scientific literature dealing with potato frying modeling. In addition, one of the major contributions offered by this work regarded the possibility of major effect of SOR on healthiness of products. An increase in water vapor production at a higher SOR played a significant role in increasing oil velocity. While the SOR did not have a substantial effect on center temperature of potato strips, surface temperature decreased with an increase in SOR. The SOR affected moisture content of the corners of the specimens, whereas it did not significantly affect the center moisture. Simulation of the longitudinal section of potato center showed that oil uptake increased with increasing SOR. The decrease in oil uptake by decreasing SOR was justified by the water vapor production and crust formation. Water vapor acted as a barrier against oil diffusion and had a significant impact on stirring the oil and creating homogeneous temperatures. Overall, this study offered a proper numerical tool to control oil absorption, leading to understanding complex mechanisms during deep-fat frying of foods. It is hoped that the results of this study could head to a further step in developing an optimized deep-fat frying process.

High purity insoluble dietary fiber (HPIDF) was extracted from Okara by compound enzyme method, and solid emulsifiers with different particle sizes were prepared by wet grinding. Its composition, structure and physicochemical properties were studied, and the influence mechanism of solid emulsifiers with different particle sizes on emulsifying properties and interface stability of Pickering emulsion was systematically studied. The results showed that the particle size of HPIDF decreased significantly, the ζ-potential, contact Angle and swelling capacity of HPIDF ncrease significantly ( p  < 0.05). HPIDF forms an adsorption layer at the oil-water interface, and some of them are connected to form a bridge network structure, which plays a role of steric hindrance. And the emulsion has excellent stability under different environmental factors. HPIDF are suitable raw materials as natural food-grade solid emulsifiers. It is cost-effective and eco-friendly to realize the high-value utilization of Okara resources, reduce resource waste, and extend the industrial chain.

Fried loach is a kind of popular flavor food. The effects of repeated frying on peroxide value (PV), acid value (AV), P-anisidine value (P-AV), total polar components (TPC) and free fatty acids (FFA) of palm oil and extracted oil from fried loach (EOL) were studied. The loach was fried in palm oil at 170 °C for 3 min and the frying was repeated 10 times. The oil from fried loach was collected and analyzed. The results showed that the TPC of palm oil exceeded the standard limit (3 mg/g) when frying 10 times. The PV and TPC of EOL were unqualified after 9 and 4 times frying (19.17 meq O2/kg and 31% respectively). The AV of the EOL reached 2.46 mg/g after 9 times frying. Palm oil has better frying performance than EOL because of its balanced proportion of saturated and unsaturated fatty acids. Palm oil can be used for 9 times frying, while the EOL has been damaged after 4 times.

This work presents the fluidized bed drying process combined with microwaves applied to Parchment coffee. In order to study different parameters that affect the quality of the grains, a mathematical model that describes energy and mass transfer during the drying process is presented and solved using Finite Elements Method (FEM) through COMSOL Multiphysics software. The model also considered the shrinkage of the grains due to water removal. Experiments were carried out in experimental prototype equipment obtaining the drying curves, which were utilized to validate the mathematical model. To study the impact of the operating conditions on the quality of the processed coffee, total polyphenolic content and antioxidant capacity were determined by Folin-Ciocalteau and free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods, respectively. Finally, nutritional parameters were related to operating conditions by the polynomial regression and desirability function methodology. Optimal operating conditions (1.4 m/s and 500 W) were found, which provides a product of excellent final quality.

Influence of moisture content (MC, 65–35%), frying temperature/time (150–200 °C, 4–12 min), and coating materials (patties coated with bread crumbs – PBC and patties coated with wheat semolina – PSC) on acrylamide formation in potato patties was investigated. Acrylamide content increased with decrease in MC and increase in temperature/time, except for PBC at higher temperatures (180 °C, 8 & 12 min and 200 °C). Morphology analysis suggested PBC to possess more porous coating that resulted in higher oil penetration leading to higher heat transfer rate, moisture evaporation and drying at higher frying temperatures. This led to an initial acceleration of acrylamide formation in PBCs at higher temperatures, followed by its degradation resulting in low acrylamide content in final product. Based on sensory analysis and lowest acrylamide formation, the optimal conditions for frying of potato patties were: (i) MC: 66.53 ± 2.2% (ii) frying temperature: 165 °C (iii) frying time: 4 min.

Images of Red Sea goatfish Parupeneus forsskali were taken in a light box to perform color and visual texture analyses. The average L* and b* values did not change significantly during storage of 7 days, but the a* values decreased ( P  <   0.05). The change of visual texture parameters energy and entropy (calculated based on histograms, and based on co-occurrence matrices [COM]), box counting-based fractal results, and texture change index (TCI) values are presented. The appearance of fish became “smoother” over time. The entropy values calculated by histograms decreased with storage ( P <  0.05), and the maximum range was 0.395. That for COM-based entropies was 71.96. TCI also decreased with storage ( P <  0.05) with a maximum range of 10.67. However, energy values increased during storage. The maximum range of the energy values calculated by histograms over time for any color channel was 0.0036. That for COM-based energies was 5.7. There was no observable change in fractal dimension. These image analysis-based parameters were compared with sensory analysis. A trained sensory panel evaluated the visual texture of a sub-set of images. The R 2 values for equation fit between sensory score and texture features were, in increasing order: COM based energy (0.185), COM-based entropy (0.313), histogram-based energy (0.375), histogram-based entropy (0.386), TCI values (0.575). Since TCI correlated better with sensory values, it is recommended to be used in this type of visual texture evaluation.