紫薯麦芽复合饮料加工工艺的研究

以紫薯和麦芽为原料制备复合饮料,利用麦芽里含有的淀粉酶水解原料中的淀粉,采用单因素实验和正交实验研究酶解温度、酶解时间、紫薯和麦芽质量比对饮料中还原糖含量和感官评分的影响,探讨还原糖含量和感官评分的相关性。结果表明,在不同加工条件下,还原糖含量的变化趋势并不总是与感官评分一致。优化的工艺条件是:酶解温度为75℃,酶解时间为1h,薯麦质量比为5:7,制得的复合饮料还原糖含量为10.45%,感官评分为21分。      

浸泡条件对燕麦发芽过程中酶活性的影响

为探究浸泡条件对燕麦发芽过程中淀粉酶、蛋白酶以及纤维素酶活力的影响,通过在不同的浸泡温度、时间和含有不同金属离子的浸泡水溶液中浸泡燕麦籽粒,测定燕麦中各酶活力随发芽时间的变化情况。研究结果表明,燕麦浸泡最优条件为浸泡温度15℃,时间8 h,浸泡水溶液添加2 mmol/L MgSO₄。在此浸泡条件下,16℃发芽10 d,发芽燕麦中的总淀粉酶、α-淀粉酶、蛋白酶和纤维素酶活力较高,分别达到54.39、25.3、0.55和1.35 U/g。      

酶法生产可可粉饮料的研究

可可粉在饮料中不稳定,可以通过酶的作用降低可可粉的粒径,改善可可粉的溶解性。分别用淀粉酶、纤维素酶、蛋白酶、木聚糖酶对可可粉进行处理,发现淀粉酶、纤维素酶对可可粉有较强的作用,蛋白酶对可可粉几乎没有作用,木聚糖酶和纤维素酶、淀粉酶协同作用才有效果。通过正交实验得到酶解的最佳工艺是:在可可粉的天然pH下,加入0.5%(w/w)的淀粉酶、2%(w/w)的纤维素酶,0.2%(w/w)的木聚糖酶,在50℃下作用4h。      

响应面法优化荸荠的酶解条件

采用α-淀粉酶对荸荠进行酶解,在单因素试验基础上,以荸荠汁中可溶性固含物含量为评价指标,通过响应面法优化酶解条件。结果表明,淀粉酶用量0.17%,酶解温度52℃,酶解2.29 h,荸荠酶解液可溶性固形物达到1.88%,出汁率达到91.23%。     

Impacts of Starch and the Interactions Between Starch and Other Macromolecules on Wheat Falling Number

Wheat with a low falling number (FN) has been particularly prevalent in recent years and has resulted in a loss of more than $140 million in a single year in the wheat industry in the Pacific Northwest of the United States. FN measurement is a standard method for the evaluation of grain α‐amylase activity, and a low FN indicates a reduction in hot wholemeal paste viscosity due to sprouting damage. Recent studies show that a low FN may result from a developmental change of starch and adverse effects of non‐α‐amylase macromolecules on wheat. In this review, we describe the principles of FN measurement and the relationship between FN and α‐amylase. We also discuss the isozymes, locations, and inhibitors of wheat α‐amylase. The effects of various aspects of starch, which is the substrate of α‐amylase, on wheat FN are also discussed, including starch structural characteristics (for example, starch granule architecture), starch susceptibility to α‐amylase, and the interaction between starch and nonstarch macromolecules (for example, lipids). Studies on the effects of planting environments (for example, temperature) and agronomic practices (for example, irrigation and fertilization) on both starch paste viscosity and FN are also reviewed. This paper highlights the importance of considering the impacts of starch and the interactions of starch and other macromolecules, including wheat α‐amylase, on wheat FN, which is important for developing strategies to solve the low FN problem.     

Inhibitory activities of kaempferol,galangin, carnosic acid and polydatin against glycation and α‐amylase and α‐glucosidase enzymes

The activities of four natural phenolics, kaempferol, galangin, carnosic acid and polydatin in scavenging free radicals, inhibiting advanced glycation end‐product (AGE) formation, α‐amylase and α‐glucosidase and trapping methylglyoxal (MGO), were evaluated in this study. Carnosic acid and galangin had the highest activity in scavenging free radicals. Kaempferol and galangin had the greatest activity in preventing bovine serum albumin (BSA) against glycation and reducing glycated proteins. Polydatin had the greatest performance in trapping MGO to reduce glycation reaction. However, there was no significant difference for kaempferol, galangin and carnosic acid in inhibiting AGE formation by BSA‐MGO reaction. Kaempferol, galangin and carnosic acid were the competitive inhibitors for α‐amylase, while kaempferol and carnosic acid were noncompetitive inhibitors for α‐glucosidase. However, polydatin showed as a mixed noncompetitive inhibitor for both α‐amylase and α‐glucosidase. The results indicated that the four natural phenolics have potential in inhibiting AGE production and the digestive enzymatic activity with different mechanisms.     

Proximate analysis,nutritional quality and anti-amylase activity of bee propolis,bee bread and royal jelly

This study discussed the proximate composition, nutritional properties, amino acid profile and anti-amylase activity of royal jelly, propolis and bee bread. Royal jelly, bee bread and propolis have lower protein and lipid and more sugar than soybeans and eggs. Soybeans have the highest energy, followed by bee bread, propolis, royal jelly and eggs. Eggs have the highest protein digestibility, followed by royal jelly, bee bread, soybeans and propolis. The primary amino acids in bee bread, royal jelly and propolis are proline, glycine, lysine, alanine, aspartic acid, serine, glutamic acid, threonine, arginine, leucine, tyrosine, phenylalanine, histidine, β-aminobutyric acid, valine, asparagine and methionine. Amino acids from royal jelly, propolis and bee bread inhibited amylase by increasing Km/Vmax and decreasing Vmax and Km through un-competitive or non-competitive strategies. Molecular docking, ultraviolet absorption and fluorescence quenching analysis showed that amino acids interact with amylase structure at the allosteric site through van der Waals interactions and hydrogen bonds. Bee products can be used as food supplements, ingredients and medications to manage diabetes by inhibiting amylase.     

Screening grape seeds recovered from winemaking by‐products as sources of reducing agents and mammalian α‐glucosidase and α‐amylase inhibitors

Grape seeds collected from vinification of various grape varieties were extracted by supercritical CO₂ for oil recovery. The defatted residues thus obtained were considered as a re‐utilisable co‐product and assessed for phenolic content, reducing capacity and inhibitory activities against mammalian α‐amylase and α‐glucosidase enzymes. Supercritical CO₂ treatment led to higher recovery of anthocyanins. Reducing capacity of phenolic extracts reached up to ~2200 mmolFe(II) kg^?1, much higher than that of various natural phenolic sources. The anthocyanin‐rich extracts showed the highest inhibitory effectiveness towards α‐glucosidase (I₅₀ value equal to ~40 μg gallic acid equivalents (GAE)/mL ~ half than acarbose). Inhibitory effectiveness towards α‐amylase activity was similar among grape varieties, with I₅₀ values comparable to that of acarbose and correlated with proanthocyanidin contents. These results could pave the way for an efficient processing of grapes, including cascade processes, namely: winemaking, oil extraction from recovered grape seeds and phenolic extraction from defatted grape seeds as potential cost‐effective nutraceuticals.