Vacuum impregnation of chitosan‐based edible coating in minimally processed pumpkin

The goal of this research was to evaluate the use of vacuum impregnation (VI) and soaking techniques (ST) in the application of edible coatings of chitosan and chitosan + lauric acid to minimally processed pumpkins (MPP). The vacuum impregnation method led to greater component incorporation (5.9% and 1.75%, respectively) in the pumpkins when compared to soaking and consequently the formation of more uniform, thicker coatings (25.6 and 22.3 μm, respectively). However, VI caused greater changes in pH, acidity, colour and firmness. Relating to water content and carotenoid content, noncoated pumpkins presented greater losses during the storage period, regardless of impregnation method. The pumpkins with edible coatings, regardless of method, presented lower numbers of psychrotrophic micro‐organisms and coliforms during the storage period. Therefore, soaking was considered the best method for the application of chitosan‐based edible coatings to minimally processed pumpkins, as it led to smaller changes in the properties of the product.     

Evolutions of rheology,microstructure and starch hydrolysis of pumpkin-enriched bread during simulated gastrointestinal digestion

In this study, the influences of pumpkin flour additions to breadmaking on evolutions of microstructure, rheology and starch hydrolysis during simulated gastrointestinal digestion were investigated. Compared to white bread (PB₀), the bread supplemented with 20% pumpkin flour (PB₂₀) showed more continuous and fibrous gel network structure with most starch granules encapsulated in the network throughout the in vitro digestion. Due to the dilution of digestive fluids and enzymatic hydrolysis, the digesta moduli and viscosity remarkably decreased as time progressed, but PB₂₀ presented significantly higher rheology compared to PB₀ in each digestion phase. At the end of intestinal phase, the in vitro starch digestibility was 69.9% for PB₀, significantly higher than that for PB₂₀ (55.4%). This is presumably attributed to the abundant dietary fibre in pumpkin flour, contributing to the increased digesta viscosity and the formation of more compact and stable gel networks that would hinder the contact of starch granules with α-amylase. In addition, the pumpkin-added breads gave satisfactory results in terms of sensory acceptability. This study has suggested promising potential of incorporating pumpkin flour in the production of functional bakery products with reduced starch digestibility while maintaining good sensory characteristics.     

南瓜籽多肽的制备及其对人体皮肤细胞的体外作用

以南瓜籽为原料制备南瓜籽蛋白。分别采用碱性蛋白酶、胰蛋白酶、风味蛋白酶、碱性蛋白酶-胰蛋白酶、碱性蛋白酶-风味蛋白酶酶解南瓜籽蛋白得到南瓜籽多肽。结果表明:碱性蛋白酶-胰蛋白酶酶解南瓜籽蛋白,水解度为27. 23%、多肽产率为39. 20%,均为5种酶解产物中最高;碱性蛋白酶-胰蛋白酶酶解制备的南瓜籽多肽中小于1 000 Da的多肽含量高达92. 72%,其具有较好的促进人体皮肤细胞增殖的性能及清除自由基作用,可降低细胞内活性氧含量,在人体皮肤细胞受到氧化损伤时,能起到良好的修复作用。     

A preliminary study of monosaccharide composition and α‐glucosidase inhibitory effect of polysaccharides from pumpkin (Cucurbita moschata) fruit

In this work, crude polysaccharide extracts were extracted from pumpkin (Cucurbita moschata) fruit by hot water. After removal of proteins and purification, polysaccharides of pumpkin fruit (PP1‐1) were subjected to structural identification. Gas chromatography analysis indicated that PP1‐1 comprised of galactose (86.4%), and glucose (13.6%). The molecular weight of PP1‐1 was measured to be 0.87 × 10⁴ Da by gel permeation chromatography. The inhibitory kinetic evaluation showed that it was non‐competitive inhibition of PP1‐1 on the α‐glucosidase‐catalysed hydrolysis of PNPG. The Michaelis–Menten constant (K_m) was 0.106 m , and the inhibitory constants (K_i), 0.435 mg.     

南瓜籽蛋白质的制备及其功能性质研究

采用碱溶酸沉法制备南瓜籽分离蛋白,通过正交试验确定最佳的提取工艺条件,并对所制得的分离蛋白的部分功能性质进行研究。结果表明,南瓜籽分离蛋白提取的最佳条件为pH11.0、温度50℃、料液比1:30(m/V)、提取时间1.5h。此时提取率为85.52%,纯度为91.07%。南瓜籽分离蛋白的等电点在5.5 左右;吸水性和吸油性都在1.2～1.6g/g 左右;乳化能力在适宜pH 值达到80% 以上;起泡性则相对较弱。     

响应面法优化制备南瓜籽抗氧化肽的工艺

以南瓜籽分离蛋白为原料,采用酸性蛋白酶酶解制备南瓜籽抗氧化肽。选用加酶量、酶解温度、pH值、底物质量浓度、酶解时间作为研究对象,以酶解液对DPPH自由基的清除率为评价指标,在单因素试验的基础上,运用Plackett-Burman筛选试验确定显著因素,然后通过三因素三水平的Box-Behnken响应面分析法优化制备南瓜籽抗氧化肽的酶解工艺条件。结果表明：酸性蛋白酶酶解南瓜籽蛋白质的最佳工艺条件为：酶解温度50℃、pH2.5、酶解时间5h、底物质量浓度0.05g/mL、加酶量6000U/g pro,在此条件下,DPPH自由基清除率可达到92.82%。     

南瓜籽制油工艺研究进展

将南瓜籽制油工艺分为压榨法、萃取法、水酶法三大类,并依据此分类对当前南瓜籽制油工艺及各工艺优、劣势进行综合论述。同时,对南瓜籽制油工艺在未来的研究方向进行了展望,以期为获得高品质南瓜籽油及推进南瓜籽油产业成熟化提供支持。     

玉米南瓜复合饮料的研制

试验以新鲜甜玉米、新鲜南瓜和菊花为主要材料,将玉米和南瓜打浆榨汁,菊花提取取汁后,研究玉米汁/南瓜汁/菊花汁的配比、柠檬酸、白砂糖和稳定剂对复合饮料感官的影响,以及均质条件对饮料均质效果的影响,得出复合饮料的最佳调配配方和工艺参数。复合饮料的最佳配方为:玉米汁/南瓜汁/菊花汁的配比为4∶4∶2,白砂糖添加量为4%,柠檬酸添加量为0.05%,复合稳定剂的添加量为黄原胶+羧甲基纤维素钠+海藻酸钠=0.1%+0.1%+0.05%,得到综合感官评分为70分;均质压力为40MPa,均质时间为5min。