Effect of post-milling process on the oxidation on the rice bran

Abstract

The rancidity of rice bran is predominantly triggered by lipophilic enzyme activities. Bran stabilisation and defatting are the typical processes to inactivate the processes that cause rancidity. However, little is known about how this impacts the development of volatile compounds related to odour in the rice bran. The effects of post-milling treatments, including the stabilisation and defatting process, on the nutritional properties and then on the development of secondary volatile oxidation compounds in the rice bran during storage were investigated. Butanal, hexanal, 2 hexenal, butanoic acid, hexanoic acid, pentanoic acid, and heptanoic acid were the discriminant volatile compounds in the non-defatted bran that were identified as the markers of rancidity of non-defatted stabilised rice. It can thus be suggested that the defatting process positively contributed to the low abundance of volatile oxidation products that are responsible for bran rancidity by slowing down the formation of lipid-derived oxidation products.

Rancid rumors or Native wisdom: Evaluating the efficacy of animal fats as insect repellents attributed to historic-period Native Americans

“…Similarly, these compounds see a rise across all oils from fresh to rancid besides Cod Oil which sees a small but not too significant decrease in total alkane hydrocarbon content. Of the other components present, those that bear importance in terms of rancidity and insect repellency are the carboxylic acids, hexanoic acid and octanoic acid as they are described in the literature to confer a rancid scent to its source and has been dubbed a marker compound for rancidity [ 52 , 53 ]. As mentioned in the results, Alligator Oil is the only oil in which both of these compounds mutually occur in a notable amount, with the level of hexanoic acid increasing significantly from oil #1 to oil #2 and there being an increase for octanoic acid as the oil becomes more rancid.…”

Protein oxidation‐induced changes in the physicochemical properties and quality of plant food

“…Potassium bromate is used as an oxidant for bread making, which has a positive effect on bread, such as increasing its volume, improving air chamber structure and retaining carbon dioxide (Shanmugavel et al ., 2020; Ncheuveu Nkwatoh et al ., 2023). In addition, protein oxidation is often thought to be related to lipid oxidation, and lipid oxidation products could accelerate protein oxidation in food (Ahmad et al ., 2023; Najamuddin et al ., 2023). Especially in emulsions, protein is easily prone to oxidation due to the presence of pro‐oxidant in the oil, water or interfacial phase (Meissner et al ., 2020).…”