Walnut Protein: A Rising Source of High-Quality Protein and Its Updated Comprehensive Review.

Recently, plant protein as a necessary nutrient source for human beings, a common ingredient of traditional processed food, and an important element of new functional food has gained prominence due to the increasing demand for healthy food. Walnut protein (WP) is obtained from walnut kernels and walnut oil-pressing waste and has better nutritional, functional, and essential amino acids in comparison with other vegetable and grain proteins. WP can be conveniently obtained by various extraction techniques, including alkali-soluble acid precipitation, salting-out, and ultrasonic-assisted extraction, among others. The functional properties of WP can be modified for desired purposes by using some novel methods, including free radical oxidation, enzymatic modification, high hydrostatic pressure, etc. Moreover, walnut peptides play an important biological role both in vitro and in vivo. The main activities of the walnut peptides are antihypertensive, antioxidant, learning improvement, and anticancer, among others. Furthermore, WP could be applied in the development of functional foods or dietary supplements, such as delivery systems and food additives, among others. This review summarizes recent knowledge on the nutritional, functional, and bioactive peptide aspects of WP and possible future products, providing a theoretical reference for the utilization and development of oil crop waste.

Research on the mechanism of microwave-toughened starch on glucolipid metabolism in mice.

Potato resistant starch (RS) was prepared by microwave-toughening treatment (MTT). This study investigated the beneficial effects of RS on high-fat diet (HFD)-induced hyperlipidemia in C57BL/6J mice by evaluating changes in the gut microbiota. The mice were fed low-fat diet with corn starch, HFD with corn starch, HFD with potato starch (HFP), or HFD with RS (HFR) for 6 weeks. The results showed that the HFR group had lower body weight and total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels compared with the HFP group. Moreover, the brown adipose tissue levels of uncoupling protein 1 (UCP-1), ß3-adrenoceptor (ß3-AR), peroxisome proliferator-activated receptor-γ (PPAR-γ), and PPAR-γ coactivator-1α (PGC-1α) were increased. Our results showed that RS supplementation increased the Bacteroidetes/Firmicutes ratio and the abundance of short-chain fatty acid-producing Allobaculum, Ruminococcus, and Blautia. Our data suggest that RS prepared by MTT may be used as a prebiotic agent to prevent gut dysbiosis and obesity-related chronic diseases, such as hyperlipidemia, and obesity.

Effects of polar compounds in fried palm oil on liver lipid metabolism in C57 mice.

Polar components (PCs) are produced during the frying of oil, affecting the quality of edible oil and posing a hazard to human health. In this study, C57 mice were fed a high-fat (HF) diet containing purified PCs for nine weeks. Their effects on lipid metabolism and liver function in animals were analyzed. Our results indicated that the contents of total PCs and saturated fatty acid increased from 6.07 ± 0.6% and 58.27 ± 0.35% to 19.17 ± 1.8% and 69.91 ± 0.51%, respectively (P < 0.01). PC intake resulted an 18.56% higher liver index in mice than that in the HF group. The PC group had the highest malondialdehyde (MDA) content (1.94 ± 0.11 nmol/mg protein) and the liver nonalcoholic fatty liver disease (NAFLD) activity score (NAS) was 4, which already showed NAFLD characteristics. In addition, the expression levels of lipid metabolism-related genes, including sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthetase (FAS), peroxisome proliferator-activated receptor-alpha, and peroxisome acyl-CoA oxidase 1, indicated that PC increased hepatic lipid accumulation by upregulating the transcriptional level of fat synthesis genes and further leads to liver damage by affecting mitochondrial function. Our results provided important information about the effects of PCs produced in the frying process of PO on animal health, which is critical for assessing the biosafety of fried products. PRACTICAL APPLICATION: The research will help promote the industrial upgrading of fried foods and help consumers build healthy lifestyles.

Comparative Study of the Oxidation Stability of High Oleic Oils and Palm Oil during Thermal Treatment.

For the controversy still existed about the oxidation stability of the high oleic oils compared with palm oil (PO), this study was aimed to explore the possible reason causing the controversies. Total polar compounds (TPC) was used to evaluate the oxidation stability of oils. Results showed there exist two kinds of lineal changes about the content of total polar compounds (TPC) in each oil, which were closely linked with the fatty acid composition and the tocochromanols content. The possible influence of the initial quality of oils also should be considered. The TPC of high oleic peanut oil (HOPO), high oleic sunflower oil (HOSO), high oleic rapeseed oil (HORO) and PO increased slowly at the initial period mainly owing to the antioxidation of tocochromanols, then sharply after 24, 48, 36 and 72 h respectively, when tocochromanols in each oil almost reduced below the detection limit. After that, the major factor would be fatty acids, particularly PUFA. It showed that the major tocochromanols in different oils (e.g. α, γ-tocotrienols in PO, α, γ-tocopherols in HORO and HOPO, and α-tocopherols in HOSO), could impose the main effects of inhibiting the TPC generation in the initial thermal treatment. The TPC in HORO significantly increased after 84 hours of heat process, which might be caused by the higher content of the polyunsaturated fatty acids (PUFA) (i.e. C18:2 and C18:3). However, the content of the saturated fatty acid (SFA) did not show statistically significant change during the thermal treatment.

Evaluation of the functional quality of rapeseed oil obtained by different extraction processes in a Sprague-Dawley rat model.

The nutritional function of vegetable oil is influenced by different oil extraction methods. In this study, the effects of different processing techniques on the quality of rapeseed oil and animal lipid metabolism were evaluated. Results showed that rapeseed oil obtained by the aqueous enzymatic extraction (AEE) method had the highest polyphenol (152.08 ± 11.44 mg GAE per kg), α-tocopherol (208.97 ± 15.84 mg kg-1), and ß-carotene (5.40 mg kg-1) contents and a better oxidation resistance. It was noted in an experiment on rats fed with diets containing rapeseed oils that AEE rapeseed oil reduces total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C), aspartate transaminase (ALT) and alanine transaminase (AST) in high-fat diet rats by 27.09%, 11.81%, 35.52%, 31.02% and 27.61%, respectively, and the body and liver weights of rats were decreased. mRNA expression indicated that AEE could significantly down-regulate fatty acid synthase (FAS) and up-regulate acyl-CoA oxidase 1 (ACOX1) gene expression levels (P < 0.05). These results suggested that the AEE method can increase the content of trace active substances in rapeseed oil and ameliorate chronic diseases induced by a high-fat diet.

Sinapine reduces non-alcoholic fatty liver disease in mice by modulating the composition of the gut microbiota.

Non-alcoholic fatty liver disease (NAFLD) is associated with low-grade chronic inflammation and intestinal dysbiosis. In this study, we investigated the potential benefits of sinapine, a rapeseed polyphenol known to exert anti-inflammatory and anti-oxidant effects, on high-fat diet (HFD)-induced NAFLD in C57BL/6 J mice and the underlying mechanisms. Four week-old mice were randomly divided into four groups and fed a low-fat diet (LFD), a HFD, a HFD with common rapeseed oil (HFD + CRO) and a HFD with sinapine in rapeseed oil (HFD + SRO) for 12 weeks. Supplementation with sinapine reduced the body weight of HFD mice by 10.99%, and decreased the levels of TG and LDL-C by 15.67% and 73.62%, respectively. In addition, sinapine also suppressed the intestinal NF-κB and TNF-α expressions and enhanced the adipose tissue IRS-1 expression in the HFD mice (P < 0.05). In terms of effects on the gut microbiota, sinapine induced a decrease in the ratio of Firmicutes to Bacteroidetes and increased the abundance of probiotics, such as Lactobacillaceae, Akkermansiaceae and Blautia, along with metabolite short-chain fatty acid (SCFA)-mediated upregulation of G protein-coupled receptor 43 (GPR43) to inhibit expression of inflammatory factors. Our collective results strongly supported the fact that the utility of sinapine as a prebiotic agent could prevent gut dysbiosis and obesity-related chronic diseases, such as insulin resistance (IR) and NAFLD.