Kinetics of Oil Absorption and Moisture Loss during Deep-Frying of Pork Skin with Different Thickness

We have investigated different properties (thickness, moisture loss, oil uptake, breaking force, color, puffing ratio during 0.5–5 min frying, microstructure, and sensory evaluation) of raw pork skins with varying thickness (2, 3, and 4 mm) after drying, intended as deep-fried snacks. We have found that the oil content, breaking force, and puffing ratio of fried pork skin with different raw skin thickness have no significant difference under similar water content (1.68–1.98 g/100 g wet weight basis, wb) after 3–5 min of deep-frying at 180 °C. Additionally, sensory score results have shown that fried pork skins with 4 mm raw skin thickness had lower flavor, texture, and overall acceptability than those with 2 mm and 3 mm raw skin thickness. Scanning electron micrographs (SEM) have revealed less holes and irregular and crack microstructure in fried pork skins with 4 mm raw skin thickness than in other groups. Different thickness of raw pork skins resulted in different effects in microstructure and influenced water evaporation and oil uptake of fried pork skin. Finally, we have proposed the kinetic equations of water loss and oil uptake of fried pork skins. Fried pork skin from raw skin thicker than 4 mm need frying at temperature higher than 180 °C to improve their puffing ratio and sensory acceptability.

Non-Target Detection of Diversity of Volatile Chlorine Compounds in Frying Oil and Study on the Influencing Factors of Their Formation

Headspace-gas-chromatography ion-mobility spectrometry (HS-GC-IMS) proved the diversity of volatile chlorinated compounds (VCCs) in frying oil in this work. First, the VCCs were obtained by headspace by heating the frying oil at 80 °C for 30 min. Then, those compounds were separated by GC capillary column in the first dimension and by IMS in the second dimension, respectively. And at last, those compounds were detected in negative ion mode for non-targeting. The study results indicated that VCCs' formation depends on the contents of NaCl and water, heating temperature and time, and the types of oil. The refining process does not affect the detection of VCCs, indicating the durability of such targets as indicators for assessing deep-frying oil. Using HS-GC-IMS, the VCCs were detected to evaluate 16 authentic refined deep-frying oils from the market with an accuracy of 100%.

Simulation of the properties of a frying composition based on ostrich oil and СО2-marjoram extract

The article reveals the optimization of a fat frying composition formulation based on ostrich oil and natural stabilizing additive using mathematical modeling of its component composition and analysis of the qualitative characteristics of the product. The object of the research was experimental versions of the frying composition obtained according to the developed recipes, which included liquid and solid fraction of ostrich oil in the following ratio, wt. %: 30,0–70,0 – the liquid one, 30,0–70,0 the solid one and 0,01–0,20 CO2 -marjoram extract. The selection and ratio of the components of the frying fat recipe was carried out using the mathematical modeling methods based on the Scheffe-simplex lattice design. A comparative analysis of the consumer properties of the fat frying composition was carried out using E.K. Harrington’s desirability function. It was shown that the best technological and qualitative characteristics of the properties of the fat frying composition were established at a ratio of 0,5 percent of liquid or 0,5 solid fractions of the frying composition mass with the addition of at least 0,1 wt. % CO2 -extract of marjoram. Positive results were also noted in samples with a minimum solid fat content of 30,0 wt. %, but with a significant amount of a stabilizing additive – 0,15 wt. %. The inhibiting effect of the introduced natural additive, which slowed down oxidative processes in the process of frying the product, were proven. It was determined that only experimental versions of deep-frying fat in the established optimum of the quantitative ratio of fractions and CO2 - extract had the highest desirability scores of 0,723 and 0,792, confirming the high level of product quality. In addition, the proposed combination of ingredients provided an increase in the time of use of the deep-frying composition, due to the increased resistance to oxidation.