Abstract:Dynamic light scattering (DLS) is a technique commonly used in laboratories to obtain the particle size distribution of colloidal solutions by measuring the fluctuations of the scattered light intensity caused by the Brownian motion of particles. In recent years, high-sensitivity DLS sensors constructed using colloidal gold nanoparticles (AuNPs) with super-strong light-scattering capabilities as probes have received widespread attention. This article first elucidates the construction strategy of the AuNP-DLS sensor and analyzes the main factors affecting its detection performance. Then a detailed introduction is given on its current application in food safety detection, and finally the development trend and major challenges faced in this field are discussed.

Abstract:Cholesteryl ester (CE) is a storage product of excessive cholesterol. Studies have shown that CE plays an important role in the diagnosis and treatment of various metabolic diseases, but the effect of dietary CE on drug treatment for non-alcoholic fatty liver disease (NAFLD) is still unclear. Using a NAFLD mouse model treated with fenofibrate (Feno), the effect of dietary CE supplementation on the efficacy of Fenotreatment was investigated. Results showed that Feno effectively alleviated NAFLD symptoms, but dietary CE supplementation weakened its therapeutic effect. Furthermore, transcriptomics analysis and RT-QPCR showed that dietary CE could reverse the expression of fatty acid metabolism and cholesterol esterification related genes, i.e., Soat1 and Soat2 mRNA, regulated by Feno. These results suggest that dietary CE intake significantly impacts the drug treatment for NAFLD, and it is speculated that the higher intake of CE may reduce the efficacy of Feno treatment. This study provides a theoretical basis for the reasonable diet for patients with NAFLD during drug treatment.

Abstract:To study the effects of food additives on the physicochemical and functional properties of liquid whole egg (LWE), three different food additives (sodium citrate, sodium D-isoascorbate, and sodium bicarbonate) were added into LWE. The physicochemical and functional properties of LWE, including pH, colour, particle size, protein solubility, turbidity, foaming properties, emulsification properties, and gelling properties, were determined. Results showed that the different types of food additives had a significant effect on the pH, particle size, protein solubility and turbidity of LWE, thereby affecting their functional properties. With the addition of 10 mmol/L sodium citrate, the pH and particle size of LWE were increased, and the protein solubility and gel hardness of LWE were improved by 6.29% and 11.52%, respectively. Adding sodium D-ascorbate at a concentration of 4 mmol/L enhanced the colour of LWE with protein solubility increased by 17.50%, which also improved the emulsification properties of the diluted LWE, with emulsifying capacity and stability increasing by 14.06% and 5.45%, respectively. The addition of sodium bicarbonate did not significantly improve the material properties of LWE, however, adding high concentration of sodium bicarbonate (200 mmol/L) resulted in reduced brightness, increased redness, and decreased yellowness of LWE, which made LWE unacceptable. The results of this study could provide a theoretical reference for the use of different types of food additives in the processing of LWE.

Abstract:To determine the key texture factors affecting the sweetness of gels, nine gels with different texture characteristics were established in this study. Their sweetness and texture characteristics were evaluated by descriptive analysis and verified by scanning gel fragments formed during oral chewing. According to the results, fragility and cohesiveness were the key texture factors that influenced the sweetness of gels. The results of gel fragment scanning showed that the samples with stronger friability and weaker cohesiveness produced more gel fragments and larger total surface area, which might be the reason for the stronger sweetness of the samples. Moreover, the sweetness of samples with lower fragility was also regulated by the moisture release, whereas that of samples with higher fragility was unaffected. The higher hardness and lower elasticity of the samples led to the formation of gel fragments with sharper edges, which required more chewing before swallowing, and resulted in more gel fragments, indirectly enhancing the sweetness of the gel.

Abstract:In order to explore the application of supercritical CO₂ extraction technology in animal fat extraction and clarify the changes in fatty acid composition during the extraction process, mutton meat was used as the raw material and supercritical CO₂ extraction technology was used to extract mutton fat. The extraction effect was analyzed, and the fatty acid mass fraction and composition were analyzed through gas chromatography-mass spectrometry. The results showed that the extraction rate of mutton fat by supercritical CO₂ was 22.04%. Compared with the untreated meat, the mass fraction of saturated fatty acid in mutton after supercritical extraction decreased significantly by 11.37% (P＜0.05), while there was no significant change in saturated fatty acids in the fat extracted by supercritical extraction. The mass fraction of monounsaturated fatty acids in mutton extracted by supercritical CO₂ significantly increased by 9.20% compared to the untreated mutton (P＜0.05)，of which the mass fraction of palmitoleic acid significantly increased by 61.00% (P＜0.05). Compared with the untreated mutton, there was no significant difference in the mass fraction of monounsaturated fatty acids in oil extracted by supercritical CO₂ (P＞0.05), however, the mass fraction of palmitoleic acid significantly increased by 70.10% (P＜0.05). In addition, trans-oleic acid was not detected in both supercritical extraction mutton and fat, and there was no significant change in the mass fraction and composition of polyunsaturated fatty acids (P＞0.05). Therefore, the supercritical CO₂ extraction technology can be used in the extraction of mutton fat, which is advantageous for increasing the mass fraction of palmitic acid, thus providing a theoretical reference and technical support for the application of supercritical CO₂ in animal fat extraction.

Abstract:This study investigated the effects of germination on nutritional quality and antihypertensive effect of highland barley by comparing the mass fraction of β-glucan, γ-aminobutyric acid, free amino acids, total polyphenols and other nutrients before and after the germination of highland barley, as well as the changes in enzyme activities such as β-glucanase and protease, and systolic blood pressure and heart rate of hypertensive rats. The results showed that the mass fraction of β-glucan, starch and protein decreased with the prolonged germination time, while the mass fraction of γ-aminobutyric acid reached its highest value at germination for 48 h. The mass fraction of total polyphenols and total flavonoids, as well as the activities of β-glucanase, amylase and protease increased with the increasing germination time. The total mass fraction of amino acids, especially the mass fraction of essential amino acids, significantly increased after germination (P<0.05), indicating that the nutritional value of highland barley could be improved by germination. In addition, compared with the non-germinated highland barley, the germinated highland barley showed a better efficacy in reducing the systolic blood pressure, heart rate, angiotensin Ⅱ and angiopoietin in hypertensive rats (P<0.05), indicating a better effect on alleviating hypertension.

Abstract:The current research studied the influence of milk fat mass fraction on sensory profiles of whole milk coffee with different roasting degrees. The just noticeable difference (JND) threshold of consumers in fat content of whole fat milk coffee was also investigated. Hereby, for light-, medium- and dark-roasted coffee, the flavor of the milk coffee with varied milk fat contents was evaluated by a quantitative descriptive analysis. Meanwhile, the JND threshold of fat mass fraction in whole milk coffee was determined by a three-alternative forced-choice detection. The results showed that the decrease of milk fat content could enhance the intensities of sourness, bitterness, astringency, smoky flavor, burnt flavor, roasted flavor, raw bean flavor and sour fragrance, and inhibit sweetness, body, caramel flavor and milky flavor. A consistent trend of influence was observed in all three coffees with different degrees of roast. However, the increased degree of roast caused more significant effect of milk fat on the flavor of coffee. Further analysis of the threshold tests showed that JND thresholds of the mass fraction of fat in light-, medium- and dark-roasted coffee were 2.59%, 2.45% and 2.36% (mass fraction), respectively. Female consumers were more sensitive to changes in fat, and their JND thresholds of fat mass fraction in deep-roasted coffee were significantly lower than those of men. The results could provide a theoretical basis for the development of low-fat milk coffee.

Abstract:Compared to natto, the fermented soybean milk produced by Bacillus natto fermentation is convenient to consume. However, it suffers from disadvantages such as low nattokinase activity and poor flavor. In this study, we first investigated the effect of adding different grains (tartary buckwheat, brown rice, coix seed, quinoa, oat flour) to enhance the ability of Bacillus natto to produce nattokinase. Results showed that tartary buckwheat was the most effective additive, increasing liquid enzyme activity from 5 803.12 U/mL to 23 326.23 U/mL when added at a 3% mass fraction. Then we evaluated the effects of tartary buckwheat powder on nattokinase activity, flavor and antioxidant activity of fermented soybean milk by Bacillus natto. Results showed that when the amount of tartary buckwheat was added at 50% mass of soybeans, the nattokinase activity, volatile base nitrogen mass concentration and total antioxidant capacity of the fermented soybean milk were 4 460.28 U/mL, 3.45 mg/dL and 16.34 mmol/L, respectively, and accounting for 161.42%, 79.84% and 196.39% of fermented soybean milk from pure soybean fermentation, respectively. Addition of tartary buckwheat significantly enhanced nattokinase activity, improved flavor, and increased antioxidant capacity of fermented soybean milk. This research provides valuable references for the development of nattokinase-enriched and convenient-to-consume natto products.

Abstract:Although the effects of phenolic on wine aroma have been reported, most of them are simulated reactions under static environment rather than the dynamic changes during real winemaking. Pinot Noir grapes are used as raw materials in this study, and two phenolic compounds, i.e., caffeic acid and rosmarinic acid, were added before alcohol fermentation. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) technology was used to investigate their effects on the main aroma compounds during the aging of dry red wine. The results showed that the mass concentrations of esters, alcohols, terpenes, norisoprenoid and acids were maintained at a relatively high level after caffeic acid treatment during the aging period of 12 months, exhibiting significant aroma preservation effects. In contrast, samples treated with rosmarinic acid exhibited lower aroma compound levels and less diversity. Further dynamic analysis using principal component analysis and odor activity values revealed that caffeic acid treatment had a high correlation with ethyl acetate, isoamyl acetate, phenylethanol, β-damascone and other aroma substances with floral and fruity aroma, suggesting its positive impact on the floral and fruity aroma of wine during aging. This study could provide valuable data for enriching the flavor chemistry of wine.

Abstract:In order to investigate the effect of temperature on the quality of passion fruit pulp based on the same sterilization intensity (F=3.0 min), the pulp was sterilized at different sterilization temperatures (88, 92, 95 and 108 ℃)respectively. The changes in physicochemical composition, color and free amino acids were comparatively analyzed, and the flavor analysis was conducted using rapid gas chromatography-electron nose and gas chromatography-mass spectrometry (GC-MS) techniques. The results showed that there was no significant difference in the total acid mass concentration (calculated as citric acid) between all the sterilized samples and the original sample (OS) (P>0.05). Compared to the OS group, the pulp treated at 108 ℃ showed a significant decrease (P<0.05) in the mass concentration of reducing sugars, however, there was no significant difference in the mass concentration of total sugar and total carotenoids (P>0.05), and the retention rate of vitamin C was also the highest (74.93%). Flavor analysis showed that the samples treated at 108 ℃ contained the same kinds of key flavor substances as the OS group, namely ethyl butyrate, ethyl caproate, ethyl acetate, ethyl caprylate and β-dihydroviolone, with a stronger similarity in aroma to the OS group. The samples treated at 92 ℃ had the highest overall free amino acid scores and a higher vitamin C retention rate (62.23%). In conclusion, 108 ℃ is the optimal sterilization temperature to maintain the nutritional compositions and sensory quality of passion fruit when F=3.0 min, and 92 ℃ sterilization is more effective only for sterilization processes below 100 ℃.

Abstract:To explore the effect of heat treatment on the quality of flaxseed meal, flaxseed meal was obtained by pre-roasting and pressing flaxseed at different temperatures. The nutritional composition, thermal characteristics and volatile components of flaxseed meal were analyzed by liquid chromatography and gas chromatography. The results showed that heat treatment below 150 ℃ caused only a slight decrease in the contents of free amino acids and lignan in flaxseed meal, and promoted the contents of dietary soluble fiber, total phenol, total flavonoids and the types of aldehydes and ketone compounds in flaxseed meal. At 180 ℃, the low threshold substances such as ketones and heterocyclic substances increase, and the beneficial components such as total free amino acids, lignan, total phenols and total flavonoids decrease significantly, which reduces the nutritional value of flaxseed meal.

Abstract:The study investigated the relationship between polysaccharides from Achyranthes bidentata and their hypoglycemic activity. The powder of Achyranthes bidentata was first extracted with ethanol, followed by hot water extraction. The resulting water extract was concentrated under reduced pressure, and the Achyranthes bidentata water extract precipitate was obtained by ethanol precipitation. Streptozocin (STZ) induction method was used to establish a diabetic mouse model, mice were given gastric medicine Achyranthes bidentata isolated components daily for eight weeks, and hypoglycemic components in Achyranthes bidentata were detected by measuring blood glucose levels and glycated hemoglobin values in mice. Hypoglycemic polysaccharide components from Achyranthes bidentata were further purified using DEAE, HW-55F and Sephacryl S-400 gel columns. The purity, relative molecular weight, and structure of the polysaccharides were determined using Sephadex G-100 gel chromatography, time of flight mass spectrometer (TOF-MS), gas chromatography (GC), and nuclear magnetic resonance (NMR). Results showed that the Achyranthes bidentata water extract precipitate significantly reduced fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) levels in diabetic mice （P＜0.05）. The hypoglycemic polysaccharides with a relative molecular weight of 1 800.5 from the water extract precipitate were identified as a homogeneous polysaccharide composed of one glucose molecule and ten fructose molecules, connected to the glucose molecule as the starting point and to C₂ of fructose. The main chain is formed by connecting the fructose molecules with β-1,2 glycosidic bonds linkage, and the branched chains are connected to C₆ of fructose. The molecular structure of the hypoglycemic polysaccharides in Achyranthes bidentata was identified for the first time.