Comparison of the Fatty Acid and Triglyceride Profiles of Big Eye Tuna (Thunnus obesus), Atlantic salmon (Salmo salar) and Bighead Carp (Aristichthysnobilis) Heads.

Big eye tuna (Thunnus obesus), Atlantic salmon (Salmo salar) and bighead carp (Aristichthys nobilis) are three representative marine and fresh water fishes. In this study, the content of total lipids (TL), triglyceride (TG) fraction, and the fatty acid profiles in the corresponding fish heads were analyzed. Meanwhile, their complicated TG molecular species were further characterized. The results showed that TG was the major lipid in these three fish heads (60.58-86.69%). Compared with other two fish heads, big eye tuna head was the most abundant in polyunsaturated fatty acids, among which eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) accounted for 64.29% and 32.77% in the TL and TG fraction, respectively. It is also worth noting that EPA+DHA/total fatty acid (TFA) value of TL and TG fraction from bighead carp head showed no significant difference with Atlantic salmon head, a typical marine fish. There were 146 TG molecules detected in big eye tuna head, 90 in Atlantic salmon and 87 in bighead carp heads. DHA or EPA accounted for 56.12%, 22.88%, and 5.46% of the total TG molecules in these three fish heads, respectively. According to principal component analysis, orthogonal projection to latent structures-discriminant analysis and the constructed heat map, the three samples could be completely differentiated based on their TG molecule fingerprints. This study is the first to compare marine and fresh water fish from the perspective of their heads' fatty acid and TG molecule profiles.

Pterostilbene and 4'-Methoxyresveratrol Inhibited Lipopolysaccharide-Induced Inflammatory Response in RAW264.7 Macrophages.

Pterostilbene (Pte) and 4'-Methoxyresveratrol (4MR) are methylated derivatives of resveratrol. We investigated the anti-inflammatory effect of Pte and 4MR in lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophages. Both Pte and 4MR significantly reduced LPS-induced nitric oxide release by inhibiting the inducible nitric oxide synthase mRNA expression. Moreover, both of them inhibited LPS-induced mRNA expression of inflammatory cytokines including monocyte chemoattractant protein (MCP)-1, interleukin (IL)-6 and IL-1ß, and tumor necrosis factor α (TNF-α), and attenuated LPS-induced nuclear factor-κB (NF-κB) activation by decreasing p65 phosphorylation. In addition, 4MR but not Pte inhibited LPS-induced the activator protein (AP)-1 pathway in RAW 264.7 macrophages. Further study suggested that Pte had an inhibitory effect on extracellular regulated protein kinases (ERK) and p38 activation, but not on c-Jun N-terminal kinase (JNK), while 4MR had an inhibitory effect on JNK and p38 activation, but not on ERK. Taken together, our data suggested that Pte induced anti-inflammatory activity by blocking mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways, while 4MR showed anti-inflammatory activity through suppression of MAPK, AP-1, and NF-κB signaling pathways in LPS-treated RAW 264.7 macrophages.

4'-Methoxyresveratrol Alleviated AGE-Induced Inflammation via RAGE-Mediated NF-κB and NLRP3 Inflammasome Pathway.

Advanced glycation end products (AGEs) could interact with the receptor for AGE (RAGE) as a sterile danger signal to induce inflammation. 4'-methoxyresveratrol (4'MR), a polyphenol derived from Dipterocarpaceae, has not been studied for its anti-inflammation effects. In the present study, we sought to explore the protective role of 4'MR in AGEs-induced inflammatory model using RAW264.7 macrophages. 4'MR significantly inhibited gene expression of pro-inflammatory cytokines and chemokines, such as interleukin 1ß (IL-1ß), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and monocyte chemoattractant protein-1 (MCP-1), as well as two typical pro-inflammatory enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2). Besides, 4'MR significantly decreased oxidative stress, demonstrated by levels of ROS production, protein carbonyl and advanced oxidation protein product via down-regulation of NADPH oxidase. Further analysis showed that 4'MR attenuated the RAGE overexpression induced by MGO-BSA. It also blocked the downstream signal of AGE-RAGE, particularly, MAPKs including p38 and JNK, and subsequently reduced NF-κB activation. Additionally, 4'MR significantly abated the activation of NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome including NLRP3 and cleaved caspase-1 and reduced the secretion of mature IL-1ß. Taken together, our results suggest that the anti-inflammatory effect of 4'MR is mainly through suppressing RAGE-mediated MAPK/NF-κB signaling pathway and NLRP3 inflammasome activation. 4'MR could be a novel therapeutic agent for inflammation-related diseases.

Dihydromyricetin as a Functional Additive to Enhance Antioxidant Capacity and Inhibit the Formation of Thermally Induced Food Toxicants in a Cookie Model.

Recently, there is a growing interest in fortifying food products with flavonoids to enhance health benefits. Naringenin, naringin, hesperetin, and dihydromyricetin are four typical flavonoids constituting a natural part of our diet. In the present work, they were fortified into a chia oil cookie model to evaluate their thermal stability during baking as well as their impact on antioxidant capacity and toxicant formation. Among them dihydromyricetin was the most unstable one (only 36.1% of which was left after baking at 180 °C for 20 min) and led to a loss of brightness in cookie. However, the antioxidant capacity of cookie fortified with dihydromyricetin was significantly enhanced compared with untreated cookie; on the other hand, dihydromyricetin showed the strongest effect to attenuate lipid and protein oxidation as well as decrease the level of fluorescent advanced glycation endproducts and carboxymethyl lysine in cookie model. Overall, among the four selected flavonoids, dihydromyricetin might be the most promising functional bakery additive enhancing the antioxidant capacity while decreasing the formation of toxicants.

Enhanced Antioxidant Activity for Apple Juice Fermented with Lactobacillus plantarum ATCC14917.

The present study examined the effect of Lactobacillus plantarum ATCC14917 fermentation on the chemical composition and antioxidant activity of apple juice. Apple juice was fermented and examined of its antioxidant activity using chemical models and cellular antioxidant assay. Furthermore, the chemical composition of fermented apple juice was characterized by LC-MS/MS. Lactobacillus plantarum ATCC14917 fermentation showed an increase in DPPH and ABTS radical scavenging activity as well as cellular antioxidant activity of apple juice. However, fermentation decreased the total phenolic and flavonoid content. Subsequent LC-MS/MS analysis of the phenolic profile indicated that the content of 5-O-caffeoylquinic acid (5-CQA), quercetin, and phloretin with strong antioxidant activity was increased significantly after fermentation. The modified phenolic composition may contribute to the increased antioxidant activity of fermented apple juice. Our findings showed that Lactobacillus plantarum ATCC14917 fermentation may be an efficient way to enhance the bioavailability of phenolic compounds and to protect cells from oxidative stress.

Unraveling the inhibitory effect of dihydromyricetin on heterocyclic aromatic amines formation.

BACKGROUND: Heterocyclic aromatic amines (HAAs) are mutagens and rodent carcinogens. Flavonoids have attracted considerable attention for development into effective inhibitors against the formation of genotoxic HAAs in thermally processed foods. RESULTS: The inhibitory effect of dihydromyricetin (DMY) on the formation of key HAAs, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx), and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), was significant. In chemical models, DMY (0.05 mmol, 0.1 mmol, and 0.2 mmol) significantly decreased the amount of PhIP formed (43.0%, 54.7%, and 75.7% respectively). A significant inhibitory effect on the formation of MeIQx and 4,8-DiMeIQx was also observed. Moreover, DMY (0.05%, 0.1%, and 0.2%) reduced the generation of PhIP (by 48.0%, 59.0%, and 80.1% respectively) and that of MeIQx (by 45.8%, 62.0%, and 76.7% respectively) in fried beef patties. CONCLUSION: The results indicate that DMY could be converted into myricetin during thermal processing, and both DMY and myricetin could trap phenylacetaldehyde, a major Strecker aldehyde of phenylalanine, in a similar manner to thus inhibit the generation of PhIP. This study provides valuable information for the development of effective strategies to minimize HAA content in thermally processed foods and also sheds light on the mechanism that accounts for the inhibitory effect. © 2017 Society of Chemical Industry.

Effect and mechanisms of thermal sterilization methods on the in vitro phenolic bioaccessibility of rose tea with milk.

Rose polyphenols, key functional components in roses, require adequate bioaccessibility for their health benefits, subject to influence by food components and processing. Investigating the impact of various thermal sterilization methods on the bioaccessibility of rose polyphenols in rose tea with milk and the underlying mechanisms, our findings indicated a significant increase in bioaccessibility following treatment at 85 °C/30 min. Conversely, 121 °C/15 min treatment decreased bioaccessibility. Examining the interaction between ß-casein in milk and rose polyphenols under different sterilization conditions, SEM and particle size analysis revealed binding, with fluorescence spectroscopy indicating non-covalent bonds. Binding forces followed the order 121 °C > 85 °C > 25 °C. Notably, at 85 °C, non-covalent binding improved polyphenol bioaccessibility, while the intensified binding at 121 °C decreased it. SDS-PAGE and amino acid analysis confirmed no covalent bond. This study establishes a theoretical basis for selecting thermal sterilization temperatures for milk-flower combinations, considering polyphenol bioaccessibility.

Antibacterial Ingredients and Modes of the Methanol-Phase Extract from the Fruit of Amomum villosum Lour.

Epidemics of infectious diseases threaten human health and society stability. Pharmacophagous plants are rich in bioactive compounds that constitute a safe drug library for antimicrobial agents. In this study, we have deciphered for the first time antibacterial ingredients and modes of the methanol-phase extract (MPE) from the fruit of Amomum villosum Lour. The results have revealed that the antibacterial rate of the MPE was 63.64%, targeting 22 species of common pathogenic bacteria. The MPE was further purified by high performance liquid chromatography (Prep-HPLC), and three different constituents (Fractions 1-3) were obtained. Of these, the Fraction 2 treatment significantly increased the cell membrane fluidity and permeability, reduced the cell surface hydrophobicity, and damaged the integrity of the cell structure, leading to the leakage of cellular macromolecules of Gram-positive and Gram-negative pathogens (p < 0.05). Eighty-nine compounds in Fraction 2 were identified by ultra HPLC-mass spectrometry (UHPLC-MS) analysis, among which 4-hydroxyphenylacetylglutamic acid accounted for the highest 30.89%, followed by lubiprostone (11.86%), miltirone (10.68%), and oleic acid (10.58%). Comparative transcriptomics analysis revealed significantly altered metabolic pathways in the representative pathogens treated by Fraction 2 (p < 0.05), indicating multiple antibacterial modes. Overall, this study first demonstrates the antibacterial activity of the MPE from the fruit of A. villosum Lour., and should be useful for its application in the medicinal and food preservative industries against common pathogens.

Development of a UPLC-MS/MS-based method for simultaneous determination of advanced glycation end products and heterocyclic amines in stewed meat products.

A novel analytical strategy was proposed to simultaneously quantify two advanced glycation end products (AGEs) including Nε-(Carboxymethyl)lysine (CML), Nε-(Carboxyethyl)lysine (CEL) and eight heterocyclic amines (HAs) including IQ, MeIQ, MeIQx, 4,8-DiMeIQx, 7,8-DiMeIQx, PhIP, Harman, and Norharman. The procedure was based on a two-step extraction, solid phase extraction (SPE) purification followed by ultra performance liquid chromatography tandem mass spectrometry. The established method showed a good linearity (R2 ≥ 0.9950), rapid processing time (8 min per sample), satisfactory recoveries (matrix spiked recoveries range from 72.2% to 119.6%) and precision (intra-day and inter-day RSDs were <19.3%). The limit of quantification (LOQ) and limit of detection (LOD) resulted to be between 0.05-15 ng/g and 0.2-50 ng/g, respectively. The validated technique was further applied to determine HAs and AGEs in eight stewed meat product samples consumed in Shanghai, with the amount of HAs and AGEs ranging from 2.851 to 18.289 ng/g and 118.158-543.493 ng/g, respectively.

Different Detection Strategies of Pediocin-Like Produced by Pediococcus pentosaceus.

In this study, Pediococcus pentosaceus C-2-1 and C23221 contained genes encoding penocin and pediocin PA-1, mined by antiSMASH. The penocin structural gene pedA from Pediococcus pentosaceus C-2-1 was successfully expressed in Escherichia coli BL21. The presence of a 6.5 kDa recombinant penocin was confirmed by Tricine-SDS-PAGE, and the specific activity increased by 1.54-fold. The bacteriocins produced by Pediococcus pentosaceus C23221 were purified using acetic ether extraction, Sepharose Fast Flow, Sephadex G-25 gel chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC); the amino acid sequence of this bacteriocin was identical to pediocin PA-1 by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), which confirmed the expression of pediocin PA-1 gene; and the specific activity increased by 24.39-fold. The heterologous expression and purification of bacteriocins have proved the expression of pediocin-like produced by Pediococcus pentosaceus. This provides a theoretical basis for the subsequent development and application of pediocin-like.

Intervention mechanism of marine-based chito-oligosaccharide on acute liver injury induced by AFB1 in rats.

Aflatoxin B1 (AFB1) is extremely hepatotoxic, a causative agent of liver cancer, and can cause symptoms of acute or chronic liver damage. Chito-oligosaccharides (COS), obtained from the degradation of chitosan derived from shrimp and crab shells, is a natural antioxidant substance and its antitumor properties have been widely studied, but less research has been done on the prevention of AFB1-induced acute liver injury. In this study, rats were acutely exposed to 1 mg/kg BW AFB1 and simultaneously gavaged with different doses of COS for 8 days. The results showed that COS attenuated the hepatic histopathological changes and reduced serum biochemical indices (ALT, AST, ALP, and TBIL) in rats. It significantly inhibited MDA content and promoted SOD and GSH-Px activity production. Moreover, it also improved hepatocyte apoptosis. Furthermore, AFB1-vs-HCOS differential genes were enriched with 622 GO entries, and 380 were Biological Processes, 170 were Molecular Functions, 72 were Cellular Components. Differentially expressed genes (DEGs) analyzed by KEGG enrichment were more enriched in pathways, such as metabolism, PPAR signaling pathway, and peroxisome. Q-PCR technique verified that Lama5, Egr1, Cyp2b1, and Gadd45g in DEGs were associated with oxidative stress damage and apoptosis. In conclusion, COS intervention reduces the effect of AFB1 on hepatic genes and thus reduces the changes in hepatic gene function.

Resistant starch intake facilitates weight loss in humans by reshaping the gut microbiota.

Emerging evidence suggests that modulation of gut microbiota by dietary fibre may offer solutions for metabolic disorders. In a randomized placebo-controlled crossover design trial (ChiCTR-TTRCC-13003333) in 37 participants with overweight or obesity, we test whether resistant starch (RS) as a dietary supplement influences obesity-related outcomes. Here, we show that RS supplementation for 8 weeks can help to achieve weight loss (mean -2.8 kg) and improve insulin resistance in individuals with excess body weight. The benefits of RS are associated with changes in gut microbiota composition. Supplementation with Bifidobacterium adolescentis, a species that is markedly associated with the alleviation of obesity in the study participants, protects male mice from diet-induced obesity. Mechanistically, the RS-induced changes in the gut microbiota alter the bile acid profile, reduce inflammation by restoring the intestinal barrier and inhibit lipid absorption. We demonstrate that RS can facilitate weight loss at least partially through B. adolescentis and that the gut microbiota is essential for the action of RS.

[Analysis of Spirulina powder by Fourier transform infrared spectroscopy and calculation of protein content].

Spirulina, Spirulina powder and dextrin standard were analyzed and identified by Infrared (IR) spectroscopy. The main components, protein (1 657 and 1 537 cm(-1)) and carbohydrate (1 069 and 1054 cm(-1)), had distinct fingerprint characteristics of IR spectra. By comparing the IR spectra of Spirulina, Spirulina powder and dextrin standard, the dominant nutrition in Spirulina powder was identified as protein and carbohydrate. The dominant accessory added in Spirulina powder was dextrin. Comparing the IR spectra of Spirulina powder from 28 different factories and figuring out the correlation provides the information about the amount of accessory. A standard curve of the ratio of absorption peak intensities to protein content was constructed to accurately determine the amount of protein in Spirulina powder.

Assessment of lipid composition and eicosapentaenoic acid/docosahexaenoic acid bioavailability in fish oil obtained through different enrichment methods.

In this study, we analyzed the eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) lipid composition of fish oil obtained through enzymatic treatment, fractional distillation and silica gel column purification, and further assessed EPA/DHA bioavailability. Lipid subclass composition information was obtained through ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS), and bioavailability tests were performed using the Caco-2 cell monolayer model. Results showed that enzymatic treatment improved the incorporation of EPA/DHA as diacylglycerol (DG) while silica gel column chromatography enriched the content of EPA/DHA as phosphatidylglycerol (PG) (12.58%) and phosphatidylethanolamine (PE) (4.99%). Furthermore, increasing the purity of EPA/DHA could improve its bioavailability and after 24 incubation, binding forms of triglyceride (TG) was superior to ethyl ester (EE) (p < 0.05) at the same purity level. Those findings are helpful to provide research basis for exploring the bioactivity of fish oil.

Apigenin and its octoic acid diester attenuated glycidol-induced autophagic-dependent apoptosis via inhibiting the ERK/JNK/p38 signaling pathways in human umbilical vein endothelial cells (HUVECs).

Glycidol is a well-known food contaminant mainly formed in refined edible oils and various thermally processed foods. Here, we studied the toxicity effects and related mechanism of glycidol on Human umbilical vein endothelial cells (HUVECs). Glycidol was found to induce Gap period 2 (G2)/Mitosis (M) phase cell cycle arrest, apoptosis, and autophagy in HUVECs. Inhibition of autophagy by 3-methyladenine (3-MA) attenuated glycidol-induced cell death, suggesting that glycidol-induced apoptosis was autophagy-dependent. Moreover, glycidol treatment induced phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal protein kinase (JNK), and p38. Inhibition of ERK, JNK, and p38 phosphorylation by the inhibitors U0126, SP600125, and SB203580 attenuated glycidol-induced autophagy and prevented glycidol-mediated reduction in cell viability, demonstrating that glycidol inhibited HUVECs growth by inducing autophagic-dependent apoptosis through activation of the ERK, JNK and p38 signaling pathways. In addition, apigenin (API) and its octoic acid diester apigenin-7 (API-C8), 4'-O-dioctanoate were found to significantly attenuate glycidol-induced cell growth inhibition by inhibiting the above signaling pathways. Collectively, glycidol induces autophagic-dependent apoptosis via activating the ERK/JNK/p38 signaling pathways in HUVECs and API-C8 could attenuate the toxicity effects.

Quality improvement of tilapia fillets by light salting during repeated freezing-thawing: Contribution of structural rearrangement and molecular interactions.

The present study evaluated the effects and underlying mechanisms of light salting on quality properties of tilapia fillets during repeated freezing-thawing. Light salting was found to improve water-holding capacity and decelerated texture softening in tilapia fillets during repeated freezing-thawing. Instead of tissue distortion and heterogeneous aggregates in control groups, light salting promoted myofibril disassembly and formation of an ordered protein network with the solubilized myofibrillar proteins. The myofibrils presented an overall amorphous appearance with the loss of M-lines, removing the restraints to myofibril swelling and solubilization from A-binds in salted groups during repeated freezing-thawing. The structural rearrangement caused by light salting facilitated the enlargement of water-holding space, transformation of tissue water, and tissue recoverability, improving water-holding capacity and texture properties of tilapia fillets during freezing-thawing. The finding provided novel insight into the improvement of quality properties of tilapia fillets by light salting when subjected to drastic temperature fluctuations.

Insight into mechanism of quality changes in tilapia fillets during salting from physicochemical and microstructural perspectives.

The effects and mechanisms of salting on quality properties of tilapia fillets were investigated in the present study. Salting under high NaCl concentrations (12 % and 15 %) resulted in low water content and decreased yields, due to the salting-out effects and low pH. Water in fillets increased in the later stage of salting in 3 % and 6 % NaCl solutions (p < 0.05). The released proteins accumulated with increasing time (p < 0.05). The TBARS value increased from 0.01 to 0.20 mg/kg after 10 h in 15 % NaCl solution (p < 0.05). The quality changes were mainly correlated to the shrinking or swelling of myofibers, extracellular spaces, and existential state of muscle proteins. In consideration of fish quality and increasing call for low sodium intake, it was recommended to prepare fillets below 9 % NaCl with short times. The finding provided instructions to obtain target quality properties from tilapia by controlling salting conditions.

Effect of acrolein on the formation of harman and norharman in chemical models and roast beef patties.

Harman and norharman were the most abundant ß-carboline-type heterocyclic amines (HCAs) detected in various foodstuffs. Unsaturated fatty acids in foods may undergo rapid oxidative deterioration during transportation, storage and heat treatment, forming reactive carbonyl species (RCS). This work studied the effects of acrolein, a highly reactive RCS, on the formation of harman and norharman in the tryptophan model system. Results showed that 0.005, 0.01, 0.015, 0.02, 0.05, 0.1 and 0.2 mmol of acrolein led to harman production increased by 528 %, 752 %, 981 %, 1172 %, 1375 %, 1288 % and 768 % respectively, and led to norharman formation increased by 116 %, 129 %, 152 %, 169 %, and 197 %, 185 % and 157 %, respectively. Furthermore, acrolein addition reduced the residue of tryptophan (up to 63.19 %), but increased the level of the intermediates including formaldehyde (up to 352 %), acetaldehyde (up to 491 %), (1S,3S)-1-Methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid (MTCA, up to 1936 %), and 1,2,3,4-tetrahydro-ß-carboline-3-carboxylicacid (THCA, up to 2142 %) in the tryptophan model system. Acrolein might react with tryptophan, harman and norharman to eliminate them directly. These data suggested that acrolein may contribute to harman and norharman formation through participating in the above complex chemical reactions. In addition, the content of harman and norharman produced in roast beef patties made of minced beef oxidized for 2, 4, 6, 8, and 10 days increased by 118 %, 188 %, 267 %, 137 %, and 48 %, respectively, and led to norharman formation increased by 140 %, 132 %, 90 %, 86 %, and 74 %, respectively compared with those made of fresh minced beef, which further illustrated that lipid oxidation products potentially contributed to harman and norharman formation.

Effect of chemical modification of κ-carrageenan on its inhibitory effect against heterocyclic amine (HAs) formation in roasted tilapia fish patties.

Sulfated κ-carrageenan (S-KC), carboxymethylated κ-carrageenan (C-KC), acetylated κ-carrageenan (A-KC) and phosphorylated κ-carrageenan (P-KC) were synthesized and tested for their inhibitory effect on heterocyclic amine (HAs) formation in roasted tilapia fish patties. Fish patties with 1 % of each hydrocolloid prepared by 90 % of fish and 10 % of an aqueous hydrocolloid dispersion were determined for HAs-levels after roasting. P-KC showed the strongest inhibitory effect against total HAs formation (20.95 %). Moreover, P-KC increased the content of creatinine and glucose but decreased the content of free amino acids in fish patties, indicating that P-KC may compete with creatinine and glucose to react with amino acids to suppress HAs generation. In addition, P-KC plus naringenin had a stronger inhibitory effect against HAs formation than P-KC or naringenin alone. P-KC at 1 % (w/w) and P-KC (0.5 %, w/w) plus naringenin (0.5 %, w/w) showed no significant effects on the color and textural properties compared to the control group (100 % fish), and had less impact on food quality than 1 % (w/w) KC. Therefore, our results suggest that chemical modification could enhance the inhibitory effect of some hydrocolloids on HAs formation, and an appropriate combination of hydrocolloids and flavonoids contributes to the attenuation of dietary exposure to genotoxic HAs.

Effects of Stigmasterol on 3-Chloropropane-1,2-diol Fatty Acid Esters and Aldehydes Formation in Heated Soybean Oil.

In this study, we investigated the inhibitory effects of three soybean isoflavones and two soybean phytosterols on the formation of 3-chloropropane-1,2-diol fatty acid esters (3-MCPDE) and aldehydes in heated soybean oil model. 0.4 mM of genistin, genistein, daidzein, stigmasterol, and ß-sitosterol significantly reduced 3-MCPDE formation by 25.7, 51.4, 21.4, 61.6, and 55.7%, and total aldehydes formation by 42.03, 43.94, 28.36, 54.74, and 39.23%, respectively. Further study showed that stigmasterol reduced the content of glycidyl esters (GEs) and glycidol, two key intermediates of 3-MCPDE, and prevented fatty acids degradation in the oils. Moreover, the effects of continuous frying time on the content of stigmasterol and the migration of stigmasterol were evaluated in the fried dough sticks model system. The content of stigmasterol in soybean oil was found to be significantly decreased with prolonged heating time. The concentrations of stigmasterol in fried dough sticks and the migration rates of stigmasterol from soybean oil to fried dough sticks decreased with repeated frying sessions. In addition, stigmasterol undergoes oxidative changes during heat treatment, and the oxidation products including 5,6α-epoxystigmasterol, 5,6ß-epoxystigmasterol, 7α-hydroxystigmasterol, 7ß-hydroxystigmasterol, stigmasterlol-3ß,5α,6ß-triol, and 7-ketostigmasterol were identified in the frying oils but not in the fried dough sticks. Overall, stigmasterol could be added to soybean oil to reduce 3-MCPDE and aldehydes formation, and reacting with GEs/glycidol and protection of lipid acids from oxidation may be the mechanism of action of stigmasterol.