酶解条件对蔗渣还原糖得率的影响及产物分析研究

研究了两种纤维素酶酶制剂(Ⅰ、Ⅱ)对蔗渣还原糖得率的影响.实验发现复酶的还原糖得率高于单酶的得率.在复酶法中,分步的还原糖得率(60%生物量)略高于一步法(59.0%生物量)得率.酶解液分析表明,蔗渣酶解产物主要有木糖、葡萄糖及少量的果糖和纤维二糖;红外分析表明酶解后残渣的纤维素吸收峰明显减弱,电镜观察得固体残渣表面出现孔洞,结构疏松,但基本框架无很大变化.     

甘蔗渣的不同预处理方法比较及其酶水解的类分形动力学

分别采用NaOH（0.45 mol/L aq.）、HCl（0.034 mol/L aq.）和高温液态水（LHW）三种方法对甘蔗渣进行预处理,并对其组分变化和酶解效果进行了比较。NaOH预处理方法获得最高的木质素去除率,达91.1%,糖损失率达23.5%;HCl和LHW预处理结果类似,木聚糖溶解率分别为85.2%和79.7%,糖损失率均约为15%,木质素去除率均小于16%。三种方法处理的甘蔗渣经纤维素酶水解后得到总单糖（葡萄糖 + 木糖）浓度分别为38.7 g/L（NaOH）、16.1 g/L（HCl）和15.6 g/L（LHW）。综合比较预处理和酶水解工艺,NaOH水溶液预处理法的糖回收率最高,其次为HCl水溶液预处理法,LHW预处理法的糖回收率最低。作为描述纤维素酶反应动力学的有力工具,类分形理论的研究表明,各种预处理后底物的不规则性依次为：HCl＞LHW＞NaOH,其与酶的有效吸附大小依次为：NaOH＞HCl＞LHW。     

甘蔗尾中酵母菌的分离与鉴定

以0～90 d打包青贮发酵的甘蔗尾为试验材料,采用传统培养法和平板划线分离法得到7株酵母菌。对纯化后的酵母菌进行形态观察、API 20 C AUX生化鉴定试剂盒鉴定及内转录间隔区（ITS）序列核糖体脱氧核糖核酸（rDNA）分子生物学鉴定,并对其生长性能进行初步探索。结果显示：菌株X1、X7、X9和X10被鉴定为Kazachstania humilis,菌株X3、X4和X6被鉴定为扁平云假丝酵母（Candida humilis）。7个菌株在培养24 h后菌液OD660 nm值达到9.90～12.84,生长性能较好。     

压榨机榨蔗能力计算公式的探讨

对于压榨机榨蔗能力的计算公式,各国未能找出其规律,只能用经验公式来表示,因而各国计算公式都不相同。本文抓住影响压榨能力的关键所在,通过分析榨辊自身入辘的机理而推出新的公式,并用工厂实际数据进行对比而得出各种公式的优劣,进一步指出新公式的意义及各种因素影响压榨能力的规律。     

氢氧化钠预处理对甘蔗渣酶解和发酵性能的影响

采用氢氧化钠预处理甘蔗渣,通过单因素和正交试验考察了不同预处理条件对甘蔗渣酶解和发酵性能的影响,并进一步分析了比表面积和木质素含量对酶解性能的影响。结果表明：预处理温度、氢氧化钠质量分数及预处理时间对酶解和发酵效率影响较为显著,最佳的预处理条件为：温度85℃、时间11 h、NaOH质量分数4.5%,在此优化条件下预处理的甘蔗渣,含纤维素56.46%,与原料相比提高了46.16%;半纤维素20.30%、Klason木质素5.79%,与原料相比分别降低了15.77%和72.87%,酶解36 h的还原糖得率为0.69 g/g（以甘蔗渣质量计）。经过氢氧化钠预处理后的甘蔗渣比表面积显著增加（由原料的0.07 m²/g最大可增加到1.07 m²/g）,木质素显著降低,有利于提高酶解和发酵效率。当比表面积超过0.30 m²/g时,酶解初始速率和酶解效率达到平衡;当木质素低于11%时,酶解效率达到平衡。     

Quantification of ethyl carbamate in cachaça produced in different agro‐industrial production systems

Popularly known by various names such as caninha, dangerous, drips, damned and many other denominations, cachaça is the genuine Brazilian drink, produced by the fermentation of sugarcane juice by yeast, followed by distillation in alambics. Considering that cachaça is the most widely consumed distilled beverage from Brazil, the knowledge of the chemical composition and the presence of potentially toxic compounds such as ethyl carbamate, considered a human carcinogen, is important. The aim of this study was to evaluate the influence of different conditions of the agro‐industrial cachaça production systems, including the variety of sugarcane, on the quantification of ethyl carbamate through the chromatographic. Thirteen unaged beverage samples, produced from different varieties of sugarcane, were analysed. Using analysis of variance and comparison of average concentrations of ethyl carbamate (Scott–Knott, α = 5%), all of the samples were found to contain contaminant levels below the ceiling established by the legislation, which is 210 µg L^?1. Copyright © 2016 The Institute of Brewing & Distilling     

甘蔗叶多糖超声波提取工艺研究

采用超声波法,通过单因素及正交试验,在不同的提取温度、提取时间、提取次数和料液比条件下探讨甘蔗叶多糖的提取工艺。实验结果表明,在最佳提取条件：提取温度60℃、提取时间60min、提取次数2次、料液比1：50（g：mL）下,甘蔗叶多糖提取率为1．973％。     

蔗髓预处理对酸催化水解的影响研究

预处理方式能够改变原料结构,在一定程度上促进原料的降解,提高目标产物的得率。通过试验研究对比了清水浸泡、碱处理、超声协同等预处理方式对蔗髓酸解的效果影响,优化了工艺条件。结果表明:超声预处理方式可以有效的提高酸解还原糖的得率,其他几种方式效果不明显。     

Formation of volatile and maturation‐related congeners during the aging of sugarcane spirit in oak barrels

The aging process of distilled spirits is a complex system based on the extraction of molecules from the wood and interactions with the liquid, the phenomenon of migration of wood constituents, as well as the formation and degradation of several compounds. Volatile and maturation‐related congeners were evaluated during the aging process of cachaça, a Brazilian sugarcane spirit aged in oak barrels. Aged cachaça presented alterations in the levels of ethanol, higher alcohols, acetaldehyde, volatile acidity, ethyl acetate, total volatile congeners, isoamyl alcohol, ethyl carbamate and copper. The aging markers (gallic acid, furfural, 5‐hydroxymethylfurfural, vanillic acid, syringic acid, vanillin, syringaldehyde, sinapaldehyde and coniferaldehyde) were compared with the compounds found in whisky, cognac, armagnac, bourbon and brandy. Monitoring the generation and evolution of congeners during the aging process allowed the characterization of cachaça and the identification of product maturity. Copyright © 2014 The Institute of Brewing & Distilling     

Maturation related phenolic compounds in cachaça aged in new oak barrels

Aging cachaça in wooden barrels improves its chemical and sensory profile and adds quality. Maturation of distilled spirits is influenced by factors such as the species of wood to make the barrels, degree of internal toasting, number of uses of the barrel and aging time. The level of maturation of distillates can be determined based on the concentration of age marker phenolic compounds extracted from the lignin of the wooden barrel, as well as their relationships with each other. This study characterises the aging process of cachaça by analysing the mechanism of lignin degradation during maturation in new oak barrels for up to 60 months in order to establish the relationship between the age of the distillate and the content of phenolic compounds extracted from the wood. The evaluation was based on the analyses of liginin derived compounds using high‐performance liquid chromatography. The level of maturation of aged cachaça can be characterised by evaluating the low molecular weight lignin‐derived phenolic substances. The total amount of benzoic acids (vanillic and syringic acids) can be taken into consideration for predicting the level of maturation of distillates. Based on the composition of maturation related congeners, it is likely that for cachaça, each year of aging in new oak barrels corresponds to approximately five years of aging for spirits in general. © 2020 The Institute of Brewing & Distilling