南瓜果实采后几种营养品质指标的变化规律

南瓜果实在采后0～80d期间,其营养成分含量均发生较大变化。通过在常温条件下储藏5个不同品种的南瓜果实后,测定其营养成分,结果表明:在采后0～80d期间,各南瓜品种果实的水分含量呈现不断下降的趋势,而在采摘后20d内下降幅度最为显著;而果实的可溶性蛋白和类胡萝卜素含量则均呈现持续上升的趋势,其类胡萝卜素含量在40～60d期间增加显著;果实的淀粉、可溶性糖和可溶性固形物含量则均在贮藏后40d达到了最大值,呈现前期增加后期下降的变化趋势。     

超滤浓缩制备南瓜果胶的工艺研究

采用超滤浓缩后乙醇沉淀的方法制备南瓜果胶.通过单因素试验,确定优化超滤条件为:超滤膜截留分子量50 kD,压力0.08 MPa,温度25 ℃,溶液pH 7.0;在该条件下,将南瓜果胶提取液浓缩至原体积1/5,再加入80%乙醇溶液沉淀果胶并洗涤果胶1次,所得的南瓜果胶纯度为80.08%,得率为8.50%,凝胶度为120.25,酯化度为31.82,干燥失重为4.26%,总灰分为3.22%,半乳糖醛酸为88.10%,pH为2.7,铅及砷含量分别为1.2 mg/kg和0.036 mg/kg,各项指标均达到国家质量标准QB 2484--2000.     

双瓜保健挂面的研制

采用单因素实验和正交实验相结合的方法,研究双瓜保健挂面的加工技术。结果显示,在高筋玉米粉中添加南瓜粉6%、苦瓜粉4%、沙蒿胶粉0.2%,加水量48%,可制得营养丰富、色味俱佳、宜于糖尿病人食用的玉米挂面。     

南瓜营养湿面的制备及其在贮藏期间品质的变化

果蔬营养湿面是一种新的功能食品,其制备工艺和参数以及在贮藏期间品质的稳定性是生产技术的关键。试验以感官评定、质构品质和蒸煮品质为评价指标,研究了加水量、加盐量和南瓜粉添加量对南瓜营养湿面食用品质的影响,同时分析了南瓜营养湿面在贮藏期间品质的变化。结果表明:加水量为33%、加盐量为2.5%和南瓜粉添加量为4%时,可制作出品质、感官俱佳的南瓜营养湿面。应用微波杀菌技术对真空包装的南瓜营养湿面处理后,南瓜营养湿面在室温3d和低温56d的贮藏过程中食用品质变化较小,能够保持良好的食用品质。     

南瓜胡萝卜发酵乳饮料的工艺研究

以南瓜、胡萝卜为主要原料,经预处理、软化、打浆等工序,添加各种辅料,采用单因素试验和响应面设计,确定南瓜胡萝卜发酵乳饮料生产的最佳配方和工艺条件.结果表明,饮料的最佳配方为南瓜汁70％,胡萝卜汁30％,脱脂乳粉2.5％,安赛蜜0.025％,复合稳定剂0.18％.饮料的最佳工艺条件为接种量3％,发酵温度42℃,发酵时间4h.     

水酶法提取南瓜子油工艺研究

以南瓜子为原料,建立以水酶法提取南瓜子油新工艺.研究表明,其最佳提取工艺为:选用纤维素酶,加酶量0.8％、酶解温度55℃、酶解时间3h、酶解pH 6.0,在该工艺条件下,提油率可达40.6％.     

南瓜酒饮品的开发研究

南瓜是一种具有极高保健价值的蔬菜。以南瓜为原料,对其酒精发酵过程进行研究,通过单因素及正交试验确定南瓜汁酒精发酵的最佳工艺条件,即:南瓜汁糖度22%,干酵母接种量5.0%,pH值为4.0,温度24℃,发酵时间3 d,酒精度可达13.8%vol。     

南瓜多糖水解工艺优化研究

南瓜资源丰富,本实验从利用南瓜中的重要成分南瓜多糖入手,研究了时间(x1)、温度(x2)和酸浓度(x3)对酸水解南瓜多糖制备低聚糖工艺的影响,通过响应面法优化的最佳工艺为:时间171min;温度64℃;硫酸浓度7.3%。在这个条件下获得的总糖含量为33.362mg/mL,同时平均聚合度为3000,达到了保护多糖含量的同时实现南瓜多糖的可控降解的目的,为南瓜的深加工利用和提高附加值提供了新的途径。     

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.