【作者】 郭淼；

【导师】 刘兴华；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2003， 硕士

【摘要】 自20世纪90年代开始，国内外都在积极研制低糖果脯，由于低糖，良好感官品质和较长保质期难以同时获得，使这一研究目前仍未达到预期效果。针对低糖果脯加工中尚未解决的有关理论和技术难点，以苹果为试材开展了较系统的研究。本文首次提出以低热值、低甜度、功能性葡聚糖代替传统的蔗糖或葡萄糖加工低糖苹果脯；分析了影响低糖苹果脯透明度、饱满度因素，从产品Aw稳定性影响的角度，探讨了低糖苹果脯保藏机理；应用微波灭酶、真空包装等技术，研究了Aw为0.8的低糖苹果脯保藏方法，旨在为果蔬糖制品低糖化提供理论和技术依据。试验结果表明： 1、以低热值、低甜度、功能性葡聚糖和果胶加工含糖量小于45％的低糖果脯，其加工工艺流程为：苹果→去皮、去心→切片→硬化、护色→漂洗→烫漂→渗透脱水→微波灭酶→葡聚糖、果胶混和液真空渗透→微波干燥→包装→成品。 2、苹果果肉真空渗透不完全是影响低糖苹果脯透明度不均一的主要因素。苹果果肉渗透脱水处理后再进行真空渗透，其渗透程度明显提高，而增加真空渗透次数对提高苹果果肉渗透效果不明显。真空渗透操作时的真空度（X₁）、真空保持时间（X₂）和温度（X₃）对苹果果肉渗透程度有显著影响，苹果果肉渗透程度（以100g果肉真空渗透后增重（Y^⌒）为指标来衡量）与真空度、真空时间和温度之间存在以下关系 Y=7.87+5.184X₁+0.568X₂+0.235X₃+0.3125X₁X₂+1.207X₁²-0.9975X₂²+0.144X₃²， 最佳工艺参数为：真空度0.09Mpa、真空保持时间35min、温度50℃。 3、以真空渗透方式对低糖果脯添加果胶、CMC-Na、明胶等亲水性胶体可明显降低半成品干燥时的收缩率，果脯饱满度提高，其中以添加果胶效果最好。 4、使用葡聚糖、果胶加工低糖苹果脯时，半成品收缩率除与成品中果胶含量（C）有关外，还受成品中葡聚糖含量（B）和含水量（A）的影响，三者对半成品收缩率影响主次顺序是B＞C＞A。 5、同传统热风干燥半成品相比，微波干燥可显著缩短干燥时间，提高成品饱满度。 6、所比较的三种糖类物质和三种亲水性胶体降低Aw能力大小为：葡萄糖＞葡聚糖＞蔗糖，果胶＞CMC-Na＞明胶。添加葡聚糖和果胶的低糖苹果脯中葡聚糖含量（X₁′）、果胶含量（X₂′）和含水量（X₃′）与Aw（Y^⌒′）之间存在以下关系：Y^⌒′=0.76-0.01145X₁′+0.0897X₂′+0.1082X₃′-0.048X₃′²含水量、葡聚糖含量对Aw影响极显著，果胶含量影响显著，此数学模型可用于预测或控制低糖苹果脯Aw。 7、Aw是影响低糖苹果脯贮存稳定性的主要因素，控制低糖苹果脯Aw在0.65～0.70范围，细菌、霉菌、酵母菌生长繁殖均受到抑制，保质期达180d；Aw在0.75～0.80范围，细菌生长繁殖仍受到抑制，但霉菌、酵母菌容易生长繁殖，引起低糖苹果脯败坏。 8、应用功率650W微波照射200g聚丙稀包装的低糖苹果脯（Aw=0.8）120s，对于霉菌、酵母菌杀灭率分别达到80%和720k以上，低糖苹果脯在室温下可安全贮存!80。!。低糖苹果脯初始菌量影响微波杀菌效果。 9、真空包装对低糖苹果脯中霉菌生长繁殖有明显抑制作用，对酵母菌生长繁殖也有一定程度地抑制作用。更多还原

【Abstract】 Since about 1990t there has been a focus on developing low-sugar preserved apples. At present the main difficulties in processing low-sugar preserved fruits is to enhance sensory properties If the products and lengthen shelf life. The experiments were carried out with apple based on vaccwm-permeation technique. A method of reducing sugar content of the preserved apples was proposed for the first time. The factors affecting the sensory properties of the product such as, transparency, pulmpress were examined, and the principle and methods which preserve low-sugar preserved apples were investigated. The principle and methods which preserve low-sugar prcscrved apples were investigated. The results were al follows:1. Substitution polydextroses for sucrose or glucose in processing preserved apples could reauce suguar content in product in desked level. The technological processing were as follows: Apples-removing peel and core- cutting into pieces -dipping in permeating solution under vaccum--inactiviating enzyme - drying products.2. The major factors affecting vaccum-permeation, such as osmosis dehydration pretreatment, vaccum-permeation times,, the main parameters of vaccum-permeation were dealt with. A mathematical model was extablelished which evaluate the amout If permeating solution trafer to apple pieces.3. Adding hydrophilic colloid, particular in pectin to apple pieces enhanced the sensory properties If the products.4. Factors of polydextroses content, pectin content and water content in product proved to have significant effect on plumpness of products.5. The drying time was shortend, the sensory quality If the products was enhanced and vitamin c retention was high by microwave-drying in comparison with air-drying.6. The effect If different carbonhydrate and hydrophilic colloid on reduction of aw was investigated, low-sugar preserved apple with Aw can be calculated as follows:Y =0.76-0.01145X,+0.0897X2+0.1082X,-0.048X,2 where Y is Aw, X, and X, is polydextroses and pectin content, X3 is water content in product, respectively.7. Aw had significant effect on microbial stableility in low-sugar preserved apples. The microbe in products with 0.65-0.70 Aw remained dormant during storage at room temperature, while molds and yeast in product with 0.75-0.80AW reproduced quickly during storage, which would affect the quality of products.8. Microwave had better killing effect on molds and yeast than heat treatment and initial numbers If molds and yeast should be comtrolled under low level. After microwave irradiation, storage experiments on products with 0.8AW were conducted.9. Compared with 100% air packing, vaccum packing could inhibit microbe reproduction, particular in molds.更多还原