Effect of Heat Treatment on Oxidation of Hazelnut Oil.

Thermal processing, a common processing method of vegetable oil in daily life, is accompanied by the formation of some harmful substances. This study determined the peroxide value, anisidine value, total peroxide value, polar compound content, fatty acid content, and core aldehyde content of hazelnut oil under different thermal processing conditions. The oxidation kinetics equation of fatty acid and temperature of hazelnut oil was established, and the correlation between the contents of fatty acid and core aldehyde and four oxidation indexes was analyzed. The results showed that the TPC of hazelnut oil exceeds 24% when heated for 10 min at 210ºC, indicating that hazelnut oil is not suitable for high temperature and long-time heating. The contents of linoleic acid and oleic acid in hazelnut oil varied significantly at different thermal processing temperatures (p ≤ 0.01). The change of linoleic acid was more consistent with the first-order oxidation kinetics model. Two core aldehydes were detected in hazelnut oil, aldehyde 9-oxo and aldehyde 10- oxo-8. The core aldehyde 9-oxo content changed most obviously with the heating temperature, and it was the main non-volatile aldehydes of hazelnut oil thermal oxidation. Correlation analysis showed that the heating temperature of hazelnut oil had a significant effect on the oxidation index (p ≤ 0.01), and linoleic acid had the strongest correlation with the oxidation index, which could reflect the overall oxidation of hazelnut oil. The total amount of core aldehyde and the content of core aldehyde 9-oxo strongly correlated with the oxidation index (p ≤ 0.01), which can be used as one of the indicators to evaluate the oxidation degree of hazelnut oil. This study is of great significance for promoting the application of hazelnut oil in daily cooking and processing.

Anti-inflammatory and intestinal microbiota modulation properties of high hydrostatic pressure treated cyanidin-3-glucoside and blueberry pectin complexes on dextran sodium sulfate-induced ulcerative colitis mice.

This study investigated the anti-inflammatory effects of cyanidin-3-glucoside (C3G) and blueberry pectin (BP) complexes on mice with dextran sodium sulfate (DSS)-induced colitis before and after high hydrostatic pressure (HHP) treatment. Real-time polymerase chain reaction (RT-PCR), western blotting, and 16S rDNA sequencing were used to study the expression of inflammation-related factors, activation of signal pathway-related proteins, and changes in the intestinal flora in ulcerative colitis (UC) mice. The results showed that HHP-treated C3G-BP complexes significantly relieved diarrhea and blood loss in the stool of UC mice and alleviated colon shortening. The potential mechanism of action involved reduction in intestinal oxidative stress mRNA expression of pro-inflammatory factors, improvement in anti-inflammatory factor levels, inhibition of the NF-κB signaling pathway, increased protein levels of Bcl-2/Bax and caspase-3/cleaved caspase-3 genes, and improved gut microbiota composition. Compared with other experimental groups, the HHP-treated C3G-BP complexes group exhibited the best anti-inflammatory effect on DSS-induced UC mice. The results may provide new ideas for using C3G-BP complexes for treating UC and help develop better processing methods.

Comprehensive lipidomics analysis of the lipids in hazelnut oil during storage.

Although hazelnut oil is is nutritious, it is easily oxidized during storage. Thus far, changes in lipids during storage have not been comprehensively analyzed. Here, we used ultra-high liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) to dynamically monitor the lipid composition of hazelnut oil during accelerated storage for 24 d. A total of 10 subclasses of 103 lipids were identified. After 24 d, the content of triacylglycerol, diacylglycerol, phosphatidic acid, phosphatidylethanolamine, phosphatidylethanol, ceramide, and total lipids decreased significantly (P < 0.05). A total of 51 significantly different lipids were screened (Variable Importance in Projection > 1, P < 0.05), and these lipids could be used as biomarkers to distinguish fresh and oxidized hazelnut oil. We also detected seven most important pathways by bioinformatics analysis to explore the mechanism underlying changes. Our results provide useful information for future applications of hazelnut oil and provide new insight into edible oil oxidation.

Targeted Lipidomics Analysis of Oxylipids in Hazelnut Oil during Storage by Liquid Chromatography Coupled to Tandem Mass Spectrometry.

Hazelnut oil is a high-grade edible oil with high nutritional value and unique taste. However, it is prone to oxidative degradation during storage. Herein, we used liquid chromatography coupled to tandem mass spectrometry to carry out a lipidomics analysis of the storage process of hazelnut oil. A total of 41 triacylglycerols and 12 oxylipids were determined. The contents of all oxylipids increased significantly after storage (p < 0.05). The oxylipid accumulation of hazelnut oil during storage was clarified for the first time. Nine significantly different oxylipids were further screened out. It was considered that the 15th day of storage is the dividing point. In addition, the lipoxygenase-catalyzed oxidation may be the major contributor to lipid oxidation of hazelnut oil. This study provides a new insight and theoretical basis to explore the storage oxidation mechanism of hazelnut oil and take quality control measures.

Effect of Storage Condition on Oil Oxidation of Flat-European Hybrid Hazelnut.

In order to study the oxidative stability of hazelnut oil stored at room temperature, hazelnut oil accelerated oxidized at 62°C was used to determine peroxide value (POV), p-anisidine value (p-AV), total oxidation value (TOTOX), the content of fatty acids and volatile oxidative products. The correlation between the content of fatty acids or volatile oxidative products and three peroxidation indexes was analyzed. The results showed that the relative content of linoleic acid in hazelnut oil decreased significantly at the duration of accelerated oxidation (p < 0.05), which was in line with the zero-order oxidation kinetics model. The absolute content of four fatty acids all accorded with the zero-order oxidation kinetics model. Both relative and absolute content of linoleic acid can set up a slightly negative linear correlation with POV, p-AV and TOTOX, respectively (p < 0.05). The oxidation of unsaturated fatty acids in hazelnut oil produced a variety of volatile oxidation products, among which hexanal, 2-octenal, 2-decenal and 3-octene-2-one could establish a significantly positive correlation with POV, p-AV and TOTOX at a certain period of time, which could be used as a new index to evaluate the oxidative decomposition of unsaturated fatty acids in hazelnut oil during storage.

Quality assessment and variety classification of seed-used pumpkin by-products: Potential values to deep processing.

Seed-used pumpkin (SUP) is known as a traditional popular crop, which is mainly processed for seeds. However, the by-products (49 times the amount of seeds) were disposed directly into the field as waste. In this study, potential values of seed-used pumpkins' by-products (SUPBs, peel and pulp) as food resource were investigated. Physico-chemical, nutritional, and aroma profile of ten varieties of SUPBs were characterized, and variety differences were also distinguished. Peel "a*" value, water, fructose, crude fat, sucrose, and Ca contents were the 6 characteristic indicators of SUPBs which screened through correlation analysis, principal component analysis (PCA), and PCA-X model. Comprehensive evaluation of physico-chemical, nutritional, and aroma profile, four varieties by-products (Jf8#, Nf8#, Rbf#, and Rf9#) were always characterized into Cluster Ⅰ. Other varieties were classified into Cluster Ⅱ based on aroma profile. However, two varieties by-products (Db1# and Xn1#) presented significant differences from others (Db2#, Db3#, Db4#, and Myxc2#) in physico-chemical and nutritional indices, they were classified as Cluster III and IV, respectively. Db1# had the highest nutritional value of soluble solid (11.78 ºBx), pectin (1,166.15 mg/ 100 g), total carotenoid (19.57 mg/ 100 g), and total sugar (13.69 g/ 100 g). Among all the SUPBs, Db1# had a relatively higher nutritional value, which was suitable as food resource for deep processing.