甲壳素和甲壳糖——潜在的纤维原料和精细化工原料

甲壳素是继纤维素之后为地球上最丰富的天然有机化合物。甲壳糖是甲壳素经去乙酰化以后所得产物。近10多年来,由于科学研究发展,目前受到许多国家学者的日益注意,国际学术会议相继召开。本文从国情出发,分别介绍了甲壳素和甲壳糖的制备及性质;甲壳素及甲壳糖的化学结构;甲壳素和甲壳糖的化学改性;甲壳素和甲壳糖的成型加工以及甲壳素和甲壳糖作为精细化工原料的潜在应用。     

Chitosan-based biodegradable functional films for food packaging applications

Chitin is the structural material of crustaceans, insects, and fungi, and is the second most abundant biopolymer after cellulose on earth. Chitosan, a deacetylated derivative of chitin, can be obtained by deacetylation of chitin. It is a functionally versatile biopolymer due to the presence of amino groups responsible for the various properties of the polymer. Although it has been used for various industrial applications, the recent one is its use as a biodegradable antimicrobial food packaging material. Much research has been focused on chitosan-based flexible food packaging and edible food coatings to compete with conventional non-biodegradable plastic-based food packaging materials. Various strategies have been used to improve the properties of chitosan - using plasticizers and cross-linkers, embedding the polymer with fillers such as nanoparticles, fibers, and whiskers, and blending the polymer with natural extracts and essential oils and also with other natural and synthetic polymers. However, much research is still needed to bring this biopolymer to industrial levels for the food packaging applications.Industrial relevanceAs a major by-product of the seafood industry, a massive amount of crustacean shell waste is generated each year, which can be used to produce value-added chitin, which can be converted to chitosan using a relatively simple deacetylation process. Being extracted from a bio-waste product using many energy-efficient methods, chitosan is much cheaper as compared to other biopolymers. Nevertheless, the exceptional properties of chitosan make it a relatively stronger candidate for food packaging applications. Chitosan has already been used in various industries, such as biomedical, agriculture, water treatment, cosmetics, textile, photography, chromatography, electronics, paper industry, and food industry. This review article compiles all the essential literature up to the latest developments of chitosan as a potential food packaging material and the outcomes of its practical utilization for this purpose.     

蚕蛹壳聚糖在食品工业中的应用

蚕蛹是一种潜在的食物资源,除含有丰富的蛋白质外,在蛹皮中大约1/4为甲壳素成分,甲壳素脱去乙酰基后的壳聚糖是一类重要的保健功能因子.本文主要从壳聚糖制备工艺、主要性质以及在食品工业中的应用几个方面进行了综述并提出几点展望与发展建议.     

黄粉虫甲壳素—壳聚糖在食品工业中应用

黄粉虫是一种潜在食物资源,除富含蛋白质外,在蛹皮中约含1/4甲壳素成分,甲壳素脱去乙酰基后壳聚糖是一类重要保健功能因子。该文主要从甲壳素、壳聚糖制备工艺、主要性质及其在食品工业中应用方面进行综述,并提出几点展望与发展建议。     

甲壳素脱乙酰酶的研究进展

甲壳素脱乙酰酶是一种专一性脱去甲壳素乙酰基的金属酶。其来源广泛,在真菌、细菌、昆虫和甲壳类动物中均有发现。酶法制备壳聚糖有望克服现有的热碱法高污染、高耗能的缺点,并制备出乙酰度均匀,分子质量变化小,脱乙酰位置固定的高质量壳聚糖产品,这使得甲壳素脱乙酰酶的研究成为热点。该文介绍了甲壳素脱乙酰酶的理化性质、所属分类、来源与生理学作用以及作用机理,并综述了产酶菌株的选育方式及酶蛋白的一般纯化过程,最后对甲壳素脱乙酰酶的应用潜力和研究中的突出问题进行了讨论,以期为今后的甲壳素脱乙酰酶研究提供思路和方向。     

Production,properties, and some new applications of chitin and its derivatives

Chitin is a polysaccharide composed from N-acetyl-D-glucosamine units. It is the second most abundant biopolymer on Earth and found mainly in invertebrates, insects, marine diatoms, algae, fungi, and yeasts. Recent investigations confirm the suitability of chitin and its derivatives in chemistry, biotechnology, medicine, veterinary, dentistry, agriculture, food processing, environmental protection, and textile production. The development of technologies based on the utilization of chitin derivatives is caused by their polyelectrolite properties, the presence of reactive functional groups, gel-forming ability, high adsorption capacity, biodegradability and bacteriostatic, and fungistatic and antitumour influence. Resources of chitin for industrial processing are crustacean shells and fungal mycelia. Fungi contain also chitosan, the product of N-deacetylation of chitin. Traditionally, chitin is isolated from crustacean shells by demineralization with diluted acid and deproteinization in a hot base solution. Furthermore, chitin is converted to chitosan by deacetylation in concentrated NaOH solution. It causes changes in molecular weight and a degree of deacetylation of the product and degradation of nutritionally valuable proteins. Thus, enzymatic procedures for deproteinization of the shells or mold mycelia and for chitin deacetylation were investigated. These studies show that chitin is resistant to enzymatic deacetylation. However, chitin deacetylated partially by chemical treatment can be processed further by deacetylase. Efficiency of enzymatic deproteinization depends on the source of crustacean offal and the process conditions. Mild enzymatic treatment removes about 90% of the protein and carotenoids from shrimp-processing waste, and the carotenoprotein produced is useful for feed supplementation. In contrast, deproteinization of shrimp shells by Alcalase led to the isolation of chitin containing about 4.5% of protein impurities and recovery of protein hydrolysate.     

甲壳质的化学反应及其应用

甲壳质由虾、蟹壳等加工而成．是地球上蕴藏量最丰富的有机物之一．近十年来．随着对甲壳质及其招生物的特性和功能认识的深化．甲壳质生产已逐步工业化。本文从国情出发．分别介绍了甲壳素及竞聚糖的化学结构、甲壳素及壳聚糖的化学改性及其衍生物的潜在应用、甲壳素和壳聚糖的开发和应用。     

影响甲壳素和甲壳胺纤维质量的因素

甲壳素纤维作为21世纪的新型绿色纤维，在服装以及医疗卫生领域都有很大的应用潜力。通过对甲壳素和甲壳胺纤维生产工艺的分析，概述了影响甲壳素和甲壳胺纤维质量的主要因素，诸如甲壳素和甲壳胺的品质、溶剂的选择、纺丝液浓度和凝固浴的确定等。     

Dye Binding Properties of Chitin and Chitosan

Chitin (β (1°4)-N-acetyl-D-glucosamine) and chitosan (deacetylated chitin) are currently available in large quantities as waste products and by-products of the shellfish industry. Their potential as carriers for food additives was studied. Significant correlations were found between dye concentration ranging from 0.2–1.6 mg dye (FD&C Red No. 40) per g chitin or chitosan and dye-binding capacity of chitin or chitosan. Within a pH range of 2.0–7.0, dye-binding capacity of chitin was stable. Chitosan gelled below a pH of 5.5 and could not be evaluated but its dye-binding capacity was constant between pH 7.0 and 5.5. Above pH 7.0 dye-binding capacity decreased for chitin as well as for chitosan but between pH 2.0 and 6.0 no dye was released from dyed chitin containing 0.77 mg dye/g chitin.     

磁性甲壳素/壳聚糖复合材料在食品安全检测中的应用研究进展

重金属污染水体、农兽药残留超标及人工色素的非法添加等引发的食品安全问题屡见不鲜,是人们一直关注的热点问题,因此选择合适的样品前处理方法尤为重要。甲壳素/壳聚糖纳米复合材料具有丰富的官能团、良好的机械性能、耐水性和无毒性等优点,是一种很好的吸附材料。磁性材料具有超顺磁性,能够通过外界磁场的驱动从溶液中迅速分离。将甲壳素/壳聚糖与磁性纳米粒子结合制成磁性甲壳素/壳聚糖纳米复合材料,可以结合两者的优点用于食品安全检测中快速分离样品复杂基质和吸附目标成分。本文就甲壳素/壳聚糖材料的结构性质及应用、纳米材料及与磁性纳米复合材料的制备方法、磁性甲壳素/壳聚糖纳米复合材料在食品安全检测应用方面的研究进展进行了归纳总结,为其在食品安全分析领域的应用研究与开发提供引导和借鉴。