Effect of sugar replacement with stevianna and inulin on the texture and predictive glycaemic response of muffins

The application of sugar replacers used in bakery products is of growing interest to the food industry, as it provides the possibility of delivering products with reduced energy and sugar. The aim of this study was to investigate the textural properties and glycaemic responses of muffins made using stevianna and inulin. Two levels of sugar replacer were used (50% and 100%). Total replacement of sucrose gave muffins with a firmer texture than the control (P < 0.05); 50% replacement, however, gave a similar texture to control. The predicted glycaemic response was reduced in sugar‐replaced muffins compared to control samples. In particular, the replacement of sucrose with 100% stevianna caused a significant decrease in the standardised area under the curve values. Therefore, there exists the potential to regulate the glycaemic response of muffins by the incorporation of 50% stevianna or 50% inulin without affecting their textural properties.     

Advances in the in vitro digestion and fermentation of polysaccharides

In vitro digestion models are widely used to study the structural changes, digestion and release of food components under simulated gastrointestinal conditions. As compared to the in vivo digestion tests, the in vitro digestion reflects the digestion and utilisation of food after ingestion and has the advantages of being time consuming, inexpensive, reproducible and free from moral and ethical restrictions. This study reviewed the current research studies on the in vitro simulated digestion of polysaccharides conducted in the last 5 years and focused on the oral, gastric and intestinal digestion models, with the aim of providing a basis for the further testing of changes in the content, structure and active ingredients of polysaccharides before and after digestion.     

Effect of thermal processing and digestive protease on the antioxidant capacity of fruit juice–milk beverage model systems under simulated gastrointestinal digestion

The effects of thermal processing and digestive protease on the antioxidant capacity of fruit juice–milk beverage (FJMB) models containing whey protein (WP) and chlorogenic acid or catechin (CAT) under in vitro digestion were investigated. After gastric digestion, the FJMB showed a significant (P < 0.05) increase in ABTS, but little change in ferric reducing antioxidant power (FRAP). Intestinal digestion decreased the FRAP and increased ABTS except in the model containing 0.1% CAT. There were different effects (none, masking, synergistic effect) in the antioxidant activity of the WP and phenolics under digestion. Pasteurisation (63 °C/30 min) had no significant effect on the FJMB's antioxidant capacity, while sterilisation (121 °C/10 min) significantly (P < 0.05) increased, decreased or had no significant effect on ABTS and FRAP under digestion, depending on the model. Pepsin and pancreatin significantly (P < 0.05) decreased the fruit phenolics' ABTS. Ferric reducing antioxidant power was not significantly influenced by pepsin during gastric digestion, but was significantly (P < 0.05) decreased by pancreatin during intestinal digestion. These results would be helpful to improve the efficacy of fruit phenolics in FJMB subjected to thermal processing and to maintain the health benefits of this kind of functional products in the food industry.     

Effect of processing and oil type on carotene bioaccessibility in traditional foods prepared with flour and puree from orange-fleshed sweetpotatoes

Consumption of Orange-Fleshed sweetpotato (OFSP) and products as source of provitamin A is being promoted to tackle vitamin A deficiency (VAD) in sub-Saharan Africa. However, limited information is available on β-carotene retention in foods and delivery after digestion. The study assessed carotene retention and bioaccessibility following in vitro digestion on traditional foods having OFSP among the ingredients. Sunflower oil, margarine and beef fat were evaluated on their effect on β-carotene bioaccessibility. Porridge and chapatis were prepared with either OFSP puree or flours in the formulations. Carotene retention was highest in chapatis (83%) as compared to porridge (65%). Micerallisation efficiency of all-trans β-carotene was comparable between similar products but greater in chapatis (62%) than porridge (11%). Sunflower oil had the highest all-trans β-carotene bioaccessibility compared to margarine and beef fat. The results support the promotion of consumption of OFSP-based products as good source of provitamin A to fight VAD.     

Effect of in vitro gastrointestinal digestion on the antioxidant activity of protein hydrolysates prepared from Cape hake by‐products

The antioxidant activity of fish protein hydrolysates may change in the digestive tract during the human gastrointestinal digestion depending on their preparation conditions. Thus, the objective of this study was to assess the antioxidant properties of Cape hake hydrolysates prepared by three different methods (HPH‐A, HPH‐B and HPH‐C) and the effect of their in vitro gastrointestinal digestion on their antioxidant properties. HPH‐A showed the highest reducing power, while HPH‐B and HPH‐C exhibited the highest OH antiradical activity. Fe²⁺‐chelating activity was similar for all hydrolysates, but HPH‐C had a higher Cu²⁺‐chelating activity comparable to that of EDTA. The in vitro gastrointestinal digestion of hydrolysates caused a decrease in the DPPH inhibition, but an increase in scavenging ABTS in all hydrolysates. Copper‐ and iron‐chelating activities increased after digestion of hydrolysates. The results showed that the gastrointestinal digestion of HPHs generally increased their antioxidant properties.     

Structural changes of meat protein of chicken sausages with various levels of salt and phosphate and their effects on in vitro digestion

The objectives of this study were to evaluate protein oxidation and in vitro digestibility of chicken sausages with various salt/phosphate combinations. Hydrophobicity increased when protein was cooked and denatured (P < 0.05). Protein oxidation was increased based on levels of SH, S-S and carbonyl groups during the cooking process (P < 0.05). Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the intensity of myosin heavy chain band was decreased while biopolymer band was denser when sausages were cooked. Sausages with 1.8% salt and 0.3% phosphate (S1P1) showed the lowest digestibility and maintained a flat and compact structure, unlike other treatments during the gastrointestinal digestive stage. SDS-PAGE of digested chicken sausages showed that protein bands were degraded into small bands followed by gradual disappearance. In conclusion, cooking process can lead to protein denaturation and oxidation, regardless of levels of salt and phosphate added. In addition, adding salt and phosphate can significantly affect the digestibility of meat products.     

巫山茶多酚提取物体外抗氧化活性研究

摘要：目的 本实验对巫山茶多酚提取物的体外抗氧化活性进行了初步评价。方法 通过使用70%乙醇提取巫山茶得到巫山茶粗提物,再依次使用不同极性溶剂萃取巫山茶粗提物得到石油醚相、乙酸乙酯相、正丁醇相和水相4个萃取相,分别测定各萃取相的总酚含量和体外抗氧化活性,选取总酚含量最高且体外抗氧化活性最强的萃取相通过HP-20大孔树脂进行富集,测定富集后的巫山茶多酚提取物总酚含量和体外抗氧化活性。结果 乙酸乙酯相的总酚含量最高,为378.1mg/g;巫山茶粗提物及其不同萃取相均具有一定的抗氧化活性,以乙酸乙酯相的体外抗氧化活性最强,DPPH?、ABTS+?、? OH的IC50值分别为0.63mg/mL、0.46mg/mL和2.35mg/mL;将乙酸乙酯相通过HP-20大孔树脂富集后得到的巫山茶多酚提取物总酚含量为637.5mg/g,总酚含量显著提高（p <0.05）,DPPH?、ABTS+?、?OH的IC50值分别为0.26mg/mL、0.16mg/mL和1.05mg/mL,体外抗氧化活性显著增强（p <0.05）。相关性分析结果显示,巫山茶粗提物及各萃取相、富集后的总酚含量与其体外抗氧化活性呈正相关。结论 巫山茶多酚提取物具有较好的体外抗氧化活性,可考虑对其进行多酚成分分析和抗氧化功能研究。     

Effects of washing and membrane removal pretreatments on the antioxidant properties of grass carp (Ctenopharyngodon idella) protein hydrolysates produced by in vitro digestion

The effects of washing and membrane removal pretreatments on the antioxidant properties of grass carp protein hydrolysates prepared through in vitro digestion were investigated. Furthermore, antioxidant hydrolysate was fractionated using ultrafiltration membranes (10, 5, 3 and 1 kDa). Oxygen radical antioxidant capacity (ORAC), DPPH and ABTS‐scavenging activity in a gastrointestinal digest produced from pretreated minced grass carp was increased 1.74‐fold, 1.08‐fold and 1.72‐fold, respectively, compared to untreated minced carp. Compared to the alkaline protease hydrolysate, ORAC, ferric reducing antioxidant power, ABTS‐ and DPPH‐scavenging activity in a gastrointestinal digest prepared from pretreated minced carp were reduced by 11.5%, 60.9%, 16.3% and 78.4%, respectively. The ultrafiltration fraction (<1 kDa) displayed the highest antioxidant activity. The size of molecular weight and the amount of hydrophobic and aromatic residues in hydrolysates played an important role in antioxidant activity. Low‐molecular‐weight fish hydrolysates could serve as a potential source of functional ingredients for promoting health.     

茶多酚对腌制猪肉护色效果的影响

茶多酚是一种天然的食品添加剂,加入茶多酚可以减少亚硝酸钠的使用。将不同量的茶多酚添加于猪肉中进行腌制,通过颜色感官评分、pH和发色率值这些测定指标的变化,初步研究了茶多酚对腌制猪肉的护色效果。发现不同茶多酚添加量的猪肉在腌制过程中,各项指标发生了显著变化。结果表明:添加0.4 g/kg茶多酚能最高限度地提高腌肉的发色率,使其pH值更接近5.6～6.0,并能在较长时间保持较好颜色。     

Improvement of thermal,microwave and ultrasonication pretreatment on the production of antioxidant peptides from sweet potato protein via in vitro gastrointestinal digestion

Effects of thermal (boiling, steaming and autoclaving), microwave and ultrasonication pretreatments on the production of sweet potato protein hydrolysates (SPPH) through in vitro gastrointestinal digestion (GID) were investigated. All pretreatments significantly increased the degree of hydrolysis (DH), antioxidant activities and molecular weight (MW) <3 kDa peptide fractions contents of SPPH in the order of autoclaving > microwave, steaming > boiling > ultrasonication (P < 0.05). Correlation analysis between peptides content and antioxidant activity suggested that antioxidant activity of SPPH mainly attributed to MW <3 kDa peptides. Diverse peptides ranged from 487.24 to 1477.74 Da with 7–13 amino acids were identified in the MW <3 kDa peptides fraction with autoclaving pretreatment and matched sporamins A, A precursor and B sequences from LC–QTOF–MS/MS analysis. Conformational structures of nine peptides were predicted with well-known antioxidant amino acids. There is a high potential for SPPH used as a functional supplement in food system.     

Changes in the quality and in vitro digestibility of brown rice noodles with the addition of ultrasound-assisted enzyme-treated red lentil protein

The effects of red lentil protein with ultrasound-assisted enzymatic treatment on the quality of brown rice noodles were investigated. The thermostability and anti-retrogradation ability of brown rice flour decreased significantly (P < 0.05), while the elastic and viscous modulus increased after adding untreated red lentil protein. Meanwhile, the cooking loss rate of brown rice noodles increased from 4.41% to 5.68%. When the red lentil protein was treated with ultrasound and enzyme, the protein–starch interaction was enhanced, and the negative effects of protein on brown rice flour and noodles were weakened. Moreover, the rice noodles with ultrasound-assisted enzyme-treated red lentil protein showed a lower starch digestibility than brown rice noodles, and its protein digestibility was significantly higher than that of rice noodles with ultrasound or enzyme-treated protein. Therefore, the addition of ultrasound-assisted enzyme-treated red lentil protein could effectively decrease predicted glycaemic index value, improve nutritional value and produce high-quality brown rice noodles.     

Effect of withering on the polyphenol oxidase level in the tea leaf

The level of polyphenol oxidase in tea leaf (Camellia sinensis) decreased on partial desiccation of the leaf during the withering process of black tea manufacture. However, sufficient activity remained, even after withering, to oxidise the available substrate in the leaf. The loss in activity due to desiccation was restored on rehydration.     

In vitro bioaccessibility of avenanthramides in cookies made with malted oat flours

This study evaluated the effects of malting and in vitro digestion on the bioaccessibility of six avenanthramides (AVNs), soluble phenols (SPs) and antioxidant capacity (ORAC) in cookies (3B, 4B, 5B) prepared with oat flour malted for three (M3), four (M4), five (M5) days, respectively. Control cookies (CTRL) were made with non-malted oat flour (M0). Five-days malting increased the AVN content of native kernels up to 10-folds, whereas SPs and ORAC tripled their values. After the in vitro digestion, AVNs showed their bioaccessibility in the following order: 5B > 4B > 3B, with a recovery of 1703 μg AVNs per 50 g portion of 5B cookies, compared to 135 μg of CTRL. Results showed that the inclusion of 27% malted oat flour was effective to formulate functional cookies with satisfactory technological properties, high AVN content and bioaccessibility.     

Effect of temperature on thermal properties of 'Record' potatoes

Heating methods were used to measure the thermal diffusivity, specific heat and density of potatoes (c.v. Record U.K.), from 40 to 90°C and for moisture contents of 72 to 79%. Thermal conductivities were calculated: maximum thermal diffusivity was at about 70°C.     

热处理对猪肉中蛋白质体外消化率及5-羟甲基糠醛形成的影响

应用模拟体外消化模型研究不同热处理的猪肉中蛋白质的体外消化率,并以5-羟甲基糠醛为指标评定蛋白质的修饰程度,探讨加热处理对猪肉中蛋白质特性的影响。结果表明,热处理10²40 min后猪肉中蛋白质的消化率增加。同时,随着热处理时间的增大,消化液中游离氨基的含量也呈现出先增加后下降的趋势。色泽分析表明:热处理后猪肉的色泽加深,L^*、a^*、b^*值增大,热处理时间大于120 min的猪肉样品色差值ΔE均在4.0以上,影响猪肉外观。猪肉样品中5-羟甲基糠醛的形成量随着加热时间的增加而显著增多（p<0.05）,蛋白质的修饰程度增大,这与蛋白质体外消化率的变化趋势一致。热处理在一定程度上可显著提高猪肉中蛋白质的体外消化率,但长时间的过热处理则影响猪肉的色泽和蛋白质的消化性,5-羟甲基糠醛形成量和色值等指标可用于评定肉类热处理中蛋白质的修饰程度。      

Effect of in vitro‐simulated gastrointestinal digestion on the stability and antioxidant activity of blueberry polyphenols and their cellular antioxidant activity towards HepG2 cells

In this study we investigated the influence of in vitro‐simulated gastrointestinal digestion on the bioaccessibility and antioxidant activity of polyphenols from blueberries (Vaccinium spp.). Total phenolic, anthocyanin, and flavonoid content was determined, and extract and digesta compositions were analysed by HPLC‐ESI‐MS/MS. The phenolic compounds were relatively stable under a gastric environment, whereas polyphenols and anthocyanins were unstable under an intestinal environment. The bioaccessibility of polyphenol, anthocyanin, and flavonoid was greatly decreased after the intestinal digestion, and the recoveries were only 13.93%, 1.95%, and 15.68% (the IN sample), respectively. Polyphenolic profile alteration occurred during in vitro‐simulated gastrointestinal digestion. Changes of phenolic compound antioxidant activity during digestion correlated with polyphenol, flavonoid, and caffeic acid concentrations. Digested extract cellular antioxidant activity was lower than non‐digested extract activity (P < 0.05). Polyphenol dose–response correlations with cellular antioxidant activity were observed. These results indicated that in vitro‐simulated gastrointestinal digestion significantly impact polyphenols and their antioxidant activity.     

美拉德反应产物对肠道微生物影响的研究进展

美拉德(Maillard)反应是食品加工、贮藏及烹饪过程中普遍存在的重要反应。Maillard反应会导致蛋白质或氨基酸的胃肠消化性下降,进而增加其进入大肠被肠道微生物发酵利用的可能性。本文主要综述Maillard反应产物对肠道微生物生长及其发酵代谢产物形成等影响的研究进展,旨在为研究Maillard反应产物、肠道微生物与健康的关系提供参考。     

茶(果)汁真空低温连续干燥与其它干燥工艺的应用比较研究

采用烘箱干燥、喷雾干燥、冷冻干燥和真空低温连续干燥工艺分别对浓缩的绿茶汁、绿橙汁进行干燥实验,并对各个样品的化学成分及品质进行分析。结果表明:四种干燥工艺对速溶绿茶粉、绿橙提取物中主要化学成分及品质的影响明显不同。以真空低温连续干燥方式进行干燥,能有效保持产品的感官品质和有效成分,适用性强。