Deep-frying. A study of the influence of the frying medium and the food nature, on the lipidic composition of the fried food, using 1H nuclear magnetic resonance

Vegetable Oils and Their Use for Frying: A Review of Their Compositional Differences and Degradation

This review provides an overview of the main vegetable oils of different botanical origin and composition that can be used for frying worldwide (olive and extra-virgin olive oil, high-oleic sunflower oil, rapeseed oil, peanut oil, rice bran oil, sunflower oil, corn oil, soybean oil, cottonseed oil, palm oil, palm kernel oil and coconut oil) and their degradation during this process. It is well known that during this culinary technique, oil's major and minor components degrade throughout different reactions, mainly thermoxidation, polymerization and, to a lesser extent, hydrolysis. If severe high temperatures are employed, isomerization to trans fatty acyl chains and cyclization are also possible. The factors conditioning frying medium degradation are addressed, including oil composition (unsaturation degree, fatty acyl chain length and "free" fatty acid content, and presence of beneficial and detrimental minor components), together with frying conditions and food characteristics. Likewise, this review also tackles how the frying oil and other processing conditions may impact on fried food quality (oil absorption, texture, flavor and color). Finally, potential health implications of fried food consumption are briefly reviewed.

New insights into molecular mechanisms of "Cold or Hot" nature of food: When East meets West

Traditional Chinese medicines are largely adopted in China and have a key importance in the world medical system. Cold-hot nature is the important characteristics of food and Chinese Materia Medica in the traditional Chinese medicine, relating to food functions in the organism. As compared to the studies on the cold and hot nature in Chinese medicine, the research studies carried out to establish the association between cold-hot nature and food are insufficient. Intending to investigate the criteria to discriminate the cold-hot nature of food and Chinese medicine scientifically, this review collected the cold-hot nature-related literature in recent 20 years in several popular databases such as PubMed, Google Scholar, and Science Direct. This review explored that the cold and hot natures are not only linked to the chemical components such as water, carbohydrates, lipids, and amino acids, but also correlated to the biological effects, comprising of energy metabolism, inflammation response, oxidation reaction, immune response, and cell growth and proliferation. Besides, this review further put forward the possibility that cold-hot nature of food and Chinese medicine exert different biological effects on the inflammatory response via regulating the signaling pathways viz. NF-κB and MAPK. More extensive studies are needed to consider the overall connections between both the biological effects and chemical components and how food processing affects the cold-hot nature of the food.

Rapid Assessment of Deep Frying Oil Quality as Well as Water and Fat Contents in French Fries by Low-Field Nuclear Magnetic Resonance

Most of the health hazards in fried foods are related to unqualified frying oil and excessive oil content. In this study, the feasibility of using low-field nuclear magnetic resonance techniques (LF-NMR) for analysis of the water and oil contents in French fries, as well as simultaneous evaluation of frying oil quality during deep frying, was investigated. Three proton populations were identified and successfully assigned to water and oil relaxation signals. Significant correlation between the T₂ relaxation parameters ( A_water and RC_oil) and the water and oil content was acquired. MRI could visualize the changes of signal intensity and spatial distribution, as well as the internal structural changes during frying. Using the correlation model built by multiple regression analysis, the total polar compounds content of the frying oil could be successfully predicted by LF-NMR relaxation characteristics, which indicates that LF-NMR was an effective method to monitor the quality of frying oil.