壳聚糖在桑椹汁澄清中的应用

研究壳聚糖对桑椹汁的澄清作用,测定桑椹汁经壳聚糖澄清后其主要成分含量及色度的变化。结果表明:壳聚糖是一种优良的果汁澄清剂,经壳聚糖澄清的桑椹汁透光率可达85%以上,且果汁中主要营养成分即色素变化不大。同时,经澄清的果汁在低温条件下贮藏5～6个月能保持良好的稳定性。     

壳聚糖在果汁澄清中的应用

壳聚糖可由海洋生物虾、蟹的外壳中提取甲壳素经过脱乙酰基得到,是迄今为止发现的唯一的阳离子动物纤维和碱性多糖。作为天然澄清剂,壳聚糖属于阳性,能与果汁中属阴性的胶体物质产生静电作用,对胶体物质有很强的凝集力,因此可以使混浊的果汁变的澄清。     

壳聚糖对玛咖汁澄清作用的影响

玛咖汁在贮存过程中易产生沉淀,需进行澄清处理,为此,采用壳聚糖澄清法,以达到快捷、经济的效果。本文在单因素的基础上,采用响应面分析法建立壳聚糖浓度、处理温度和澄清时间对玛咖汁澄清度影响的多元回归数学模型。结果表明:壳聚糖浓度0.22g/L、处理温度39℃、澄清时间32min,玛咖汁的澄清度为98.36%。玛咖汁澄清前后,其易引起果汁混浊的物质果胶、水溶性蛋白质、总酚的损失率依次为58.90%、42.93%、2.16%,玛咖汁中主要活性成分芥子油苷、水溶性生物碱、VC和总糖的损失率分别为0.56%、0.33%、0.34%和0.89%,表明在响应曲面法(Response surface methodology,RSM)优化条件下,壳聚糖澄清能较好的保留玛咖汁中的的主要活性成分。      

壳聚糖在猕猴桃果汁澄清中的应用研究

应用壳聚糖澄清猕猴桃果汁单因素试验的研究表明，壳聚糖使用的最小剂量为０．５ｇ／Ｌ，最适ｐＨ为３～３．５，最适温度为４０～６０℃；用此澄清工艺条件澄清的猕猴桃清汁，透光率可达９５％以上，且营养成份损失不大。     

水溶性壳聚糖在果汁澄清中的应用研究

研究水溶性壳聚糖对果汁的澄清作用,测定果汁经壳聚糖澄清后主要成分的变化。结果表明,2%壳聚糖水溶液能提高果汁的透光率,且不影响果汁的营养成分,是一种有效的果汁澄清剂。     

壳聚糖与黄原胶对菠萝汁澄清效果的研究

以浊度、色差和透光率为指标,壳聚糖和黄原胶为澄清剂,研究了壳聚糖/黄原胶对菠萝汁的澄清效果,确定了最佳的工艺参数,并在单因素实验的基础上,通过正交实验,得出澄清菠萝汁的最适工艺为:温度35℃,时间70min,壳聚糖(10g/L)与黄原胶(10g/L)的比例1∶1,果汁pH3.4,验证实验结果表明,此时浊度为0.93NTU,透光率高达98.5%,菠萝汁的色差b*=14.47,在此工艺条件不但能得到满意的澄清效果,还能呈现菠萝原汁的亮黄色。     

羧甲基壳聚糖糖用澄清剂的制备及结构表征

为了研究取代SO2的新型糖用澄清剂,以壳聚糖（CTS）为原料、氯乙酸（CA）为改性剂,采用微波辐射技术制备羧甲基壳聚糖。以该产物对蔗汁澄清的脱色率和纯度差为评价指标,优化制备条件,使用扫描电镜（SEM）、红外光谱仪（FT-IR）及核磁共振（1H-NMR）分析产物性能及表征结构。结果表明,在mNa OH∶mCTS=5∶1,微波功率600W,辐射时间12min,mCA∶mCTS=6∶1条件下,所制备的羧甲基壳聚糖为N,O-羧甲基壳聚糖,水溶性得到改善、对蔗汁中带电胶体的吸附范围及电中和性能有所增加;其对蔗汁澄清的脱色率和纯度差分别达50.45%和1.63%,通过对比亚硫酸法澄清工艺的实际生产数据,认为羧甲基壳聚糖可以取代SO2作为糖用澄清剂应用于蔗汁澄清过程。      

酶法澄清西番莲果汁的工艺研究

通过单因素试验分析探讨了果胶酶的种类、添加量、pH、温度和时间对西番莲果汁澄清效果的影响；淀粉酶Amylase AG 300L添加量为0.02ml／kg可有效除去果汁中的淀粉物质。进行正交试验确定酶法澄清西番莲果汁的最佳工艺条件，结果表明，果胶酶PECTINEX@ BE XXL的添加量为0．14ml／kg、pH5．0、温度45℃、时间50min，可得到澄清透明，具有新鲜西番莲风味的果汁，澄清效果理想。     

壳聚糖对马蹄汁澄清效果的影响

研究壳聚糖澄清马蹄汁的工艺条件,以马蹄汁透光率为指标,重点探讨壳聚糖添加量、处理温度及澄清时间等工艺参数对马蹄汁澄清效果的影响。结果表明,壳聚糖澄清马蹄原汁的最佳工艺条件是:壳聚糖用量0.8 g/L,温度40℃,pH值5.0(自然pH值),澄清时间45 min。澄清后的马蹄汁透光率可达93.9%,与原汁相比,其VC含量、可溶性固形物及总糖含量无明显变化,果胶含量去除80%以上。     

Antibacterial activity of chitin,chitosan and its oligomers prepared from shrimp shell waste

The antimicrobial activities of chito-oligosaccharides against four Gram-positive and seven Gram-negative bacteria were compared to chitosan and chitin with an emphasis on the effects of biopolymer molecular weight (Mv) and degree of deacetylation (DD). Chitin was isolated from shrimp (Parapenaeus longirostris) shell waste by sequential chemical treatments. Chitosan and its oligomers N-acetyl chito-oligosaccharides and chito-oligosaccharides were prepared by deacetylation and chemical hydrolysis, respectively. Chitin exhibited a bacteriostatic effect on Gram-negative bacteria, Escherichia coli ATCC 25922, Vibrio cholerae, Shigella dysenteriae, and Bacteroides fragilis. Chitosan exhibited a bacteriostatic effect on all bacteria tested, except Salmonella typhimurium. The oligomers exhibited a bactericidal effect on all bacteria tested.     

壳聚糖澄清荔枝果醋的研究

研究了壳聚糖对荔枝果醋的澄清效果,测定了荔枝果醋澄清前后主要成分的变化。经过单因素试验和正交试验,壳聚糖澄清荔枝果醋的最佳工艺条件确定为：壳聚糖用量5g/L、澄清处理pH3.5、澄清处理时间8h、澄清处理温度30℃。在此最佳工艺条件下,壳聚糖对荔枝果醋有良好的澄清效果,可以较好地降低荔枝果醋中蛋白质和单宁的含量,从而有效地改善其贮藏稳定性。     

壳聚糖的超声波降解及对芒果汁澄清效果的研究

以透光率为指标,以壳聚糖澄清和超声波澄清方法为对照,探讨经超声波降解的壳聚糖在不同功率、温度、作用时间和pH条件下对芒果汁澄清效果的影响。实验结果表明:经超声波降解的壳聚糖对芒果汁有较好的澄清效果,且明显优于未经降解的壳聚糖澄清对照组和单一的超声波澄清对照组,且分别在功率160W、温度50℃、作用时间30min、pH3.5条件下的透光率最高。     

甲壳素／壳聚糖在果蔬贮藏和果汁澄清中的应用

论述了甲壳素/壳聚糖的分布及性质，以及壳聚糖在果蔬贮藏和果汁澄清中的应用，壳聚糖作为一种新型澄清剂和保鲜剂具有广阔的应用前景。     

壳聚糖在果汁澄清工艺上的应用

介绍了勃聚糖的分布和一般性质,以及壳聚糖在果汁澄清上的运用,指出作为一种新型澄清剂,壳聚糖具有不少优良的特性,可以替代传统的澄清处理。     

酶制剂在果蔬汁澄清及加工中的应用研究进展

当前我国果蔬汁工业迅猛发展,因酶制剂可解决果蔬汁加工中出汁率低、澄清难、易褐变、风味物质易流失和苦味物质难去除等问题,在该领域中得到广泛的应用。目前在果蔬汁加工中应用的酶制剂主要有果胶酶、纤维素酶、淀粉酶、葡萄糖氧化酶、柚苷酶等。本文介绍了果胶酶、纤维素酶、淀粉酶等常见酶制剂在提高果蔬出汁率方面的作用机制及应用进展,比较了酶制剂与其他方法对果蔬汁澄清效果的差异,陈述了葡萄糖氧化酶、柚苷酶、β-葡萄糖苷酶等在改善果蔬汁感官品质方面的应用现状。在分析酶制剂在果蔬汁加工中存在问题的基础上,对酶制剂的应用前景和发展方向进行了展望,为酶制剂在果蔬汁行业的应用提供进一步的依据和参考。     

Deacetylated chitin used as adsorbent in production of clarified pineapple syrup

A study of clarification of pineapple wastes syrup by a combined process of membrane ultrafiltration (UF), ion exchange and adsorption techniques using partially deacetylated chitin (PDC) as adsorbent material was conducted. Chitin from Black Tiger shrimp shell was used after undergoing deproteination, demineralisation and deacetylation with different concentrations of sodium hydroxide (NaOH). The performance of cation resin (Dowex 88), anion resin (Dowex 66) and PDC as adsorbent material were evaluated. Effects of flow rate ranging from 10 to 50 ml min⁻¹ on operation and regeneration of the resins were also investigated. Chitin yield was about 31·2% of the shrimp shells, corresponding to about 89% recovery of the total chitin content of the shells. When treated with 5%, 10%, 20% and 30% NaOH, the degree of deacetylation increased with increasing concentration of sodium hydroxide. In ion exchange process, cation resin removed more than 90% of K⁺, Mg²⁺ and Ca²⁺ from UF mill juice at a flow rate of 30 ml min⁻¹. In adsorption process, anion resin (Dowex 66) had more colorant removed (94% T) from UF mill juice than PDC treated with 30% NaOH (84·4% T). The optimum flow rate for cation resin was 10 ml min⁻¹ for both operation and regeneration while for PDC, 30 ml min⁻¹ was optimum for operation and 10 ml min⁻¹ for regeneration. The concentrated pineapple syrup was clear with a colour value of 70·2% and pH value of 4·96. The main reducing sugars after concentration were glucose, fructose and sucrose at 29·05, 15·72 and 18·62% (w/v), respectively. © 1998 SCI.     

Use of chitosan,honey and pineapple juice as filling liquids for increasing the microbiological shelf life of a fruit‐based salad

The activity of some natural compounds for extending the storage life of fresh‐cut fruits was examined. In particular, the effect of chitosan, honey and pineapple juice used as filling solution on the growth of mesophilic bacteria, psychrotrophic bacteria, lactic acid bacteria and yeasts, in fruit‐based salads stored at 4 °C, 8 °C and 12 °C was investigated. Honey showed the greatest antibacterial effect on mesophilic and psychrotrophic bacteria, with non significant effects on lactic acid bacteria and yeasts. The antimicrobial activity of chitosan affected the growth of all microbial groups considered (mesophilic and psychrotrophic bacteria, lactic acid bacteria and yeast), particularly, in conditions of refrigerated storage. In contrast, no difference in the growth of monitored microorganisms between samples containing pineapple juice and control was detected.     

果汁牛奶的流变性质测评

对自制果汁牛奶和市售类似产品进行了流变学研究。结果表明,与市售类似产品相比,自制产品的初始黏度及剪切稳定后的黏度均较高,具有明显的“假塑性”,黏度对温度的变化较敏感,感官特征良好。     

果汁的流变特性研究

研究了果汁的流型与组成的关系及其流动活化能与频率因子的关系。发现果汁的流型与组成有关,不含果胶的果汁流型为牛顿流体,含果胶的果汁流型为假塑性流体;果汁的流动活化能与频率因子间存在着补偿关系。