This study aimed to investigate the antioxidant mechanisms of Maillard reaction-derived volatile pyrroles - 2-acetylpyrrole (2AP), N-methylpyrrole (NMP) and pyrrole-2-carboxaldehyde (2PC) on hemoglobin (Hb) oxidation. The findings revealed that during 4-days storage, the 2AP group showed lower carbonyl and dimerised tyrosine contents of Hb than the untreated Hb group, and 2AP preserved the conformation of heme porphyrin in Hb through microenvironmental polarity modulation. In stark contrast, NMP exhibited pro-oxidative properties with accelerated protein aggregation, while 2PC exhibited a biphasic effect - suppressing Hb oxidation initially but accelerating it subsequently - this late-stage oxidation was attributed to its enhanced Hb surface hydrophilicity. Generally, the inhibition activity of the three pyrroles is closely related to the position of the substituents in the pyrrole ring and the availability of electrons. This study provided a basis for investigating the antioxidant properties and applications of Maillard reaction-derived volatile small molecules in fresh meat preservation.

The pH-shift method selectively separates proteins from complex materials based on their isoelectric points. In this study, the technique was applied to chicken by-products (CBP) for protein extraction. To reduce oxidation in the resulting CBP protein isolates (CBPIs), black chokeberry press cake (BCPC)—an agricultural by-product—was added during processing. The results showed that alkaline treatment produced a more cohesive structure in CBPIs, while the addition of BCPC improved their otherwise deteriorated microstructure. Further analysis revealed that this structural improvement was linked to BCPC’s ability to reduce free sulfhydryl content and surface hydrophobicity. Compared to acid treatment, alkaline extraction enhanced the functional properties of CBPIs, including emulsification, foaming, and texture. Among them, the foaming capacity and foam stability of CBPI-12 were improved by 30.0 % and 44.4 %, respectively, compared to the acid treatment. Overall, combining pH-shift processing with BCPC not only minimized oxidation in CBPIs but also optimized their protein structure and functionality. This approach presents a promising strategy for sustainable resource utilization and efficient protein extraction.

The Maillard reaction products (MRPs) inhibit fish lipid oxidation; however, whether they act with the endogenous antioxidants in fish is unclear. This study investigated the effects of MRPs on the primary nonenzymatic endogenous antioxidants and endogenous antioxidant enzymes in carp meat, as well as their interaction mechanisms. The results showed a synergistic antioxidant effect of MRPs with α-tocopherol, which is the main nonenzymatic antioxidant in fish muscle. The synergistic mechanisms primarily included distribution differences, where MRPs and α-tocopherol exerted antioxidant effects in different media, and an electron transfer mechanism, where MRPs enhanced the antioxidant activity of α-tocopherol through electron transfer. Additionally, complementary enhancement occurred when MRPs and α-tocopherol used different molecular mechanisms to reduce various lipid pro-oxidants. Furthermore, MRPs protected the activities of endogenous antioxidant enzymes. These findings demonstrated that MRPs synergistically interacted with the endogenous antioxidants to inhibit oxidation and protect the related enzymes in fish, highlighting their antioxidant role in fish muscle.

As a pro-oxidant, myoglobin (Mb) can induce lipid oxidation in meat. In this study, Fourier-transform infrared spectroscopy (FTIR), circular dichroism (CD), fluorescence spectroscopy, UV-vis spectrophotometry, and fluorescence microscopy were used to evaluate the impact of Maillard reaction products (MRPs) formed from glucose and lysine on the oxidative stability of carp Mb. MRPs were found to inhibit the auto-oxidation of Mb, reducing MetMb production by 8.45%. The static quenching of fluorescence indicated that MRPs interacted with Mb through hydrogen bonding and van der Waals forces, thereby enhancing the alpha-helical content by 11.57% and reducing the random coil content by 2.72%. The enhanced stability of this advanced structure helps to minimize the exposure of amino acid in the side chain and prevent the formation of MetMb. Fluorescence microscopy showed that MRPs reduce porphyrin ring degradation, consequently decreasing heme iron release. It is evident that MRPs play a crucial role in maintaining Mb structure stability and inhibiting its oxidation.

Lipid oxidation is the major cause of quality deterioration in freshwater fish, especially mediated by myoglobin (Mb). This study aimed to investigate the antioxidant mechanism of Maillard reaction products (MRPs) in Mb-mediated lipid oxidation in common carp (Cyprinus carpio). MRPs exhibited promising antioxidant and antimicrobial capacities based on the reduced content of peroxide and thiobarbituric acid-reactive substances and inhibited microbial growth. MRPs inhibited the oxidation of Mb by lowering the transfer from oxymyoglobin to metmyoglobin and improving the stability of heme iron. The correlation analysis showed that MRPs regulated the formation of free radicals by maintaining the reduced structure of Mb and the integrity of heme iron, and also directly inhibited the formation of oxidation products in a chain radical reaction. The texture and electronic nose analysis indicated that MRPs could delay the structural disruption and flavor deterioration of surimi. Therefore, MRPs could effectively inhibit Mb-induced lipid oxidation and further control the resulting changes in the flavor and texture of surimi.

The main products, including intermediate products, and the consequent browning substances and advanced glycation end products (AGEs) are formed during different periods of the Maillard reaction (MR), and their antioxidant effect on meat varies with the product contents and proportions. This study aimed to assess the antioxidant activity of Maillard reaction products (MRPs) formed at different heating stages and evaluate their capacities to inhibit oxidation in the common carp and chicken. The 2,2’-azinobis (3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picryl-hydrazil (DPPH), and ferric reducing antioxidant power (FRAP) assays were used to determine the antioxidant activities of MRPs, and UPLC-MS/MS were used to detect the formation of AGEs. The results indicated that the antioxidant capacity of MRPs improved with the accumulation of intermediate products and browning substances, particularly nonfluorescent intermediates that play crucial roles. MRPs (6 h) showed effective antioxidant capability, including a 60

This study aims to investigate the relationship between casein oxidation and moisture status in the presence of milk fat to clarify the role of fat on water in milk powder. The results showed that at the same water activity (a(w)), the faster oxidation of whole milk powder (WMP) is attributed to the high proportion of free water and immobilized water in them, indicating that the adsorption of milk fat mainly depended on multilayer water and the entrapped water. In the diffusion-limited reaction, changes in water state affected more than radicals on casein oxidation. Glass transition temperature (Tg) was also affected by the water state of lipid adsorption. At low a(w) (<0.4), the water content of WMP and skim milk powder (SMP) was similar, but the Tg of WMP was significantly lower than SMP, especially when a(w) was 0.33, its Tg was <0. It suggested that water state rather than water content was the main factor affecting Tg. Especially, because the mobile water absorbed by milk fat in WMP reduced Tg, which further led to the acceleration of lactose crystallization, casein oxidative aggregation, and Maillard reaction.

Polycyclic aromatic hydrocarbons (PAHs) widely exist in food, which potentially harm human health. This study compared the effect of apple polyphenol (AP) and three antioxidants - ascorbic acid, tert-butyl hydroquinone and butylated hydroxytoluene on barbecued pork. The inhibition pathway of PAHs in barbecued pork were investigated by measuring DPPH radical scavenging rate, peroxide value (POV), and thiobarbituric acid value (TBARs). The results indicated that AP and antioxidants showed positive effects in inhibiting of PAHs formation (20.03-37.36%), scavenging DPPH radical activity (48.56-64.37%), reducing POV value (45.08-64.89%), and TBARs value (13.74-32.72%). Based on strong correlation between the PAHs content and the POV (r = 0.844, p = 0.017) and TBARs values (r = 0.825, p = 0.022) analyzed by Pearson correlation, AP can be used to control the formation of PAHs. The inhibition effect of AP on PAHs showed concentration-dependent. OPLS-DA analysis revealed that 0.20% AP had the best inhibition on PAH in barbecued pork, and elasticity, cohesiveness, adhesion, chewiness, and recovery of barbecued pork were improved significantly.

The amines produced in heating meat products are harmful to human health, but the current detection method is not simple enough. In this study, QuEChERS technology combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to establish a method for the simultaneous detection of acrylamide (AA), nitrosamines (NAs) and heterocyclic amines (HAAs) in processed meat products. The results showed that the analytic methods of 20 amines in the three components showed good linearity (R2>0.991) in the corresponding concentration range, and the detection limit and quantification limit were 0.01~1.6 ng/g and 0.03~4.8 ng/g, respectively. The average daily recovery rate was between 66.3%~111.5%, and the intraday precision was between 0.78%~9.0%. The daily accuracy range of the 5×LOQ spiked level calculation for each amine was 3.4%~9.4%. The method was applied to the analysis of AA, NAs and HAAs in four meat products for grilling, in them 9 amines were detected with the concentration range of 0.08~31.26 ng/g.

Milk is a highly nutritional food rich in protein and fat that is prone to deterioration by oxidation and glycation reactions at storage and processing. In this study, glycation products and lipid oxidation products contents in skim milk, whole milk, and milk fat simulation groups were determined to evaluate the effect of milk fat components on glycation at 120 °C for 60 min. The increase rate of carbonyl compound, main advanced glycation end products (AGEs) levels, and glycation sites number of α-casein and β-casein are higher in whole milk than that in skim milk, indicating that milk fat promoted protein glycation significantly. In milk fat simulation groups, oleic acid and linoleic acid (LA) were added to milk fat in skim milk proportionally, promoting the formation of glycation products; however, palmitic acid had no such effect. LA exhibited strong promotion on AGEs formation. Lipid oxidation radicals, protein carbonyl amine condensation, and carbonyl compound formation were critical factors for milk glycation, according to OPLS-DA results. Therefore, radicals of fat oxidation are speculated to trigger the early glycation, and carbonyl compounds of fat oxidation act as important intermediates of glycation, fat type, form, and its degradation rate, thus play essential roles in milk glycation.

This study aimed to explore the effect of secondary lipid oxidation products (SLOPs) on hemoglobin (Hb) in chicken model. The fluorescence quenching technique and molecular docking were employed, and the apparent binding constants Ksv and the binding site numbers of SLOPs with Hb were calculated. The results revealed that three SLOPs (hexanal, benzaldehyde, and 2-pentanone) obviously promoted the oxidation of Hb, which is consistent with the change of Hb hydrophobicity, particle size, polydispersity index and zeta potential. The SLOPs strongly quenched the intrinsic fluorescence of Hb and triggered the alterations in the Hb structure. Hydrophobic interaction was the main force between SLOPs and Hb. Among the three SLOPs, hexanal demonstrated more stronger oxidation on Hb, which is closely related to its hydrophobic ability and structure characteristic, especially 10 μM hexanal is more prone to form an obvious unfolded structure and caused molecular aggregation than lower concentrations.

To investigate the effect of pH on lipid oxidation of chicken muscle, chicken hemolysates were added to washed chicken muscles to analyze lipid oxidation at pH 5.7, 6.3, and 7.2. The results showed that with a blue shift of the Soret peak, oxyhemoglobin gradually transformed to methemoglobin during storage, the shape of porphyrin rings of heme in fluorescence electron microscopy changed from round to trail-like structure. These changes were more significant at low pH. Comparing hemoglobin (Hb) structure, the distance of amino acids between the E10 of lysine and metHb-7-propionate groups is longer at pH 5.7 than other pHs, which makes solvent easily enter the heme cavity, leading to the severe destruction of Hb. The linear correlation between color and lipid oxidation also further confirmed that the increased oxidation of chicken Hb causes more rapid lipid oxidation in pH 5.7 than the other 2 pHs (p < 0.05).

糖基化反应是高营养食品常见的一类反应,食品中的脂类成分对糖基化反应有很大影响.本研究以葡萄糖和卵清蛋白(OVA)建立糖基化对照体系,与含有不饱和脂肪酸(UFA)的模型组进行对比,探究脂肪酸氧化对于糖基化反应产物二羰基化合物、晚期糖基化终产物(AGEs)及糖基化蛋白结构的影响.结果表明UFA通过不同方式促进二羰基化合物的形成,并通过改变OVA高级结构显著促进糖基化反应.脂肪酸的不饱和度与二羰基化合物含量、TBA值、POV值均成正比,与羧甲基赖氨酸和吡咯素含量成反比.通过SEM结构模型的路径分析可知,脂质氧化次级产物对二羰基化合物的影响力较强(路径系数0.814),对两种AGEs的影响力相对较弱(0.246);脂质氧化初级产物对两种AGEs的影响力强于二羰基化合物.

Research on advanced glycation end-products (AGEs) and their formation pathways in food processing has gradually increased because AGEs are associated with human health, especially with involvement of lipids. In this study, radicals and glycation products were detected via electron spin resonance (ESR) and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) respectively. The correlation of important intermediates was used to explain the effect of oleic acid (OA) on the glycation products and pathways. The results indicated OA participation decreased the content of stable radicals and glycosyl compounds in Maillard Reaction (MR). The oxidation of OA produced active radicals, and electron transfer caused lysine to transform radical form. These radicals participated in the formation of fructosyllysine (FL) with glucose (Glc) via the MR. The participation of OA is acted as inhibiting the way of Glc autoxidation and promoting the glycation pathway from FL to 3-deoxyglucosone (3-DG) to fluorescent-AGEs. Orthogonal projection to latent structures discriminant analysis results indicated that 3-DG, D-glucosone and methylglyoxal are key products in discriminating the glycation reaction.

To study the effect of calcium ion (Ca2+) on chilling injury (CI) in green peppers (Capsicum annuum L.), green peppers were treated with calcium chloride (CaCl2) and chlorpromazine (CPZ) at 4 degrees C storage temperature. The results showed that two calcium ions exhibited opposite functions. The CaCl2 treatment effectively regulated the activity of antioxidative enzymes to promote the AsA-GSH cycle, reduced the accumulation of O-2(-) and H2O2 generated from the metabolic cycle, inhibited the accumulation of MDA and proline, and the degradation of membrane lipid components, as well as the increase in relative conductivity to maintain the integrity of cell membrane. The reason that CaCl2 can improve the cold resistance of green bell pepper fruit may be attributed by the decreased expression and activity of PLC gene and DGK gene, which delayed the degradation of membrane lipid, thereby maintaining cell membrane stability and reducing the occurrence of CI.

<正>西瓜是一年生蔓生草本植物,全国各地都有栽培。多年来,生产中西瓜品种蔓长2～4米,栽培时控制在1.8～2米,节间长8～10厘米,具有很强的分枝能力,在主蔓上生长出许多侧蔓,在地面上占具庞大的位置。近年来,西瓜的育种目标主要围绕果实性状方面进行研发,其他方面未见新的进展和突破。笔者从2002年开始

There are certain healthcare factors in honey,lemon,and black tea,and their resources are abundant.Researches were conducted on the production technique of black tea beverage mixed with honey and lemon.Major production process and parameters were determined so as to produce savoury and mellow black tea beverage with rich nutrition.

Samples of fermentation liquors of fungus carsis and their parents were taken for the study.The sample liquors were pretreated according to prescribed procedure including extraction,centrifuging,concentration and etc.An aliquot of the concentrated sample solution was used for HPLC and TLC determinations.It was found that due to the difference of degradation ability of fungus crasis and their parants in the fermented liquors,different degradation products were obtained in different sample liquors,on the base of which differentiation of fungus crasis was performed.

Used mulberry and Chinese wolfberry,nutritional mulberry-Chinese wolfberry wine of special taste was produced by the following processes:active dry yeast 0.02%,7 d,temperature controlled 25℃,sugar content was adjusted to 18%before fermentation,the S0 2 addition was 70 mg/L~80 mg/L.The product wine had agreeable sour,sweet flavor and pure taste.Besides,the fruit flavor and the wine flavor matched up in perfect harmony.

The process of pre-treatment and extracting pectin from orange hull was studied in this paper. The optimal process conditions were gained by single experiments and orthogol test as follows: Pre-treatment as grind comminution, water and material proportion was 15∶1, pH2.0, extracted temperature was 95 ℃, extracted time was 30 min, and the extracting yield of 20 g the pectin was 2.36 g.