一种减少总固不溶物污染的山羊皮保存方法

原料皮作为制革原材料，主要成分是含有70％水分的蛋．白质，其极易遭受细菌的侵害，因此在制革前进行防腐保存是非常重要的。而用皮重40～50％的食盐进行防腐保存是目前较常用的一种方法，但它会在制革过程中产生大量的总固不溶物（TDS）和氯离子污染。因而相关机构纷纷寻求其它可替代的防腐方法来减少环境污染，据此本文尝试用少盐（皮重5％的食盐＋偏亚硫酸氢钠（SMBS））和无盐（只用SMBS）防腐方法以消除污染，还根据制革加工中产生的TDS量，防腐保存过程中产生的微生物数量，所保存生皮的物理、生化、抗微生物性能和热学性能及加工后坯革的机械性能等结果来评价保存方法的效果。     

降低浸水废液中总固体不溶物山羊皮的有效防腐

制革中用到的原料皮多为含水70%的蛋白质,极易受微生物的影响,因此转变成革前原料皮的防腐是必要的。传统防腐方法现仍在广泛使用,但是由于该过程使用的NaCl量高达40%~50%,产生大量的污染主要以总固体不溶物TDS、氯化物形式存在。因此化学家们基于降低污染为出发点对防腐方法做了大量研究,本文研究了少盐(5%中性盐及焦亚硫酸钠混合物)、无盐(仅用焦亚硫酸钠)防腐体系,从TDS减少量、微生物污染控制方面研究了生皮的物理、生化、微生物、热力学特征并比较了各类防腐方法制备的成革性能。     

一种降低辣椒红色素不溶物含量的方法

辣椒红色素是一种天然类胡萝卜素,色泽鲜艳,着色力强,安全无毒,广泛应用于食品、医药、化妆品等领域。目前辣椒红色素普遍存在不溶物、杂质含量高的问题,产品利用程度低,严重影响经济效益。本研究以辣椒红色素为原料,确定了一种辣椒红色素纯化的方法。其最佳脱胶剂添加量即加酸量为2.5g,加水量为40g,加盐量为3g;在此条件下处理的辣椒红色素不溶物可降低至0.38%。使用此方法处理得到的辣椒红素呈深红色,具有诱人的光泽,流动性好,品质高;并经过车间中试取得了良好的效果。     

几种检测溶解性总固体方法的比较

目的通过比较几种常见的检测溶解性总固体的方法,寻求一种结果准、时间短的检测方法,以便提高检测溶解性总固体的效率。方法对蒸汽法(国标法)、100℃水浴法、烘箱法、电热板、电炉法等几种测定方法的检测结果和检测时间进行比较,并进行统计学计算分析。结果电热板法、电炉法的测定结果与国标方法测定结果相比较,超出国标偏差要求;100℃水浴法测定14份水样的结果与国标法无显著性差异。结论用100℃水浴法测定饮用水中溶解性总固体结果与国标一致,且用时比国标法缩短2 d,显著提高了检测效率,是值得推广的检测方法。     

乳固形物浓度对酸羊乳品质的影响

采用真空浓缩方法,获得固形物含量为12%、14%、16%、18%的羊乳,用其生产酸羊乳,探索不同乳固形物浓度对酸羊乳品质的影响。从凝乳特性、质构特性、风味物质、乳酸菌数等方面对不同固形物浓度的酸羊乳进行分析,并且采用扫描电镜对其微观结构进行比较。结果显示,随着羊乳固形物浓度的提高,酸羊乳的凝乳时间显著降低,酸度逐渐增大,持水性显著增高;酸羊乳的双乙酰浓度和乙醛浓度在乳固形物含量为16%时达到最高;随着羊乳固形物浓度的提高,酸羊乳的黏度增加了149.07%,酸羊乳的硬度、黏性、胶黏度显著增加,凝聚力显著降低;乳酸菌总数在羊乳固形物含量为16%时达到最大值6.35×10~9CFU/m L;羊乳固形物含量为16%时,酸羊乳的微观结构非常致密,空隙直径最小为2.85μm。羊乳固形物含量为16%时,酸羊乳风味最佳,凝乳质地较硬,黏度较高,乳酸菌总数最高,品质最好。     

Quantitatively determining the total bacterial count of raw goat milk using dielectric spectra

The objective of this study was to evaluate dielectric spectra as a means of quantitatively determining total bacterial count (TBC) of raw goat milk. The dielectric spectra, including dielectric constant (ε′) spectra and dielectric loss factor (ε″) spectra, and TBC of 154 raw goat milk samples were measured using network analyzer and plate count methods, respectively. Owing to the poor linear relationship between TBC in logarithm and permittivities at a single frequency, chemometrics was used to reduce noise, identify outliers, select effective variables, and divide sample sets. Several linear models, such as multiple linear regression, ridge regression, and least absolute shrinkage and selection operator, were established to determine TBC based on the effective spectra of ε′, ε″, and their combination (ε′+ε″). The results indicated that the models built using the spectra of ε′+ε″ and ε′ had excellent TBC prediction performance. The best model was multiple linear regression based on ε′+ε″ spectra with the residual predictive deviation of 3.26. This study shows that the dielectric spectra had great potential to quantitatively and rapidly determine TBC of raw milk.     

基于蒙特卡洛法的溶解性总固体测量不确定度评定

目的研究出一种基于蒙特卡洛法的溶解性总固体测量不确定度评定的方法。方法按照溶解性总固体实验过程,建立对应的数学模型。根据蒙特卡洛法分布传播和总结过程,得出蒙特卡洛法的评定结果。同时使用Guide 98-3:2008《测量不确定度表示指南》进行评定,得出对比结果。结果使用蒙特卡洛法所得结果为208.0 mg/L,扩展不确定度为5.2 mg/L。区间为197.82~218.18 mg/L。指南法评定结果为208.6 mg/L,扩展不确定度为5.6 mg/L,计算结果为(208.6±5.6)mg/L。结论蒙特卡洛法评定结果与测量不确定度表示指南法评定的数据相近,可以用于计算溶解性总固体的测量不确定度,为实验室工作人员提供了一种实用的测量不确定度评定方法。     

Effective diffusivity of total solids and pectic substances from apple tissue

The effective diffusivities of total solids and pectic substances from apple tissue were determined at 40 and 60°C in water and buffer; the addition of pectolytic enzyme in buffer at 40°C was also investigated. the Fickian model for unsteady-state diffusion was applicable in all cases. Effective diffusivity values both for total solids and soluble pectic substances in deionized water were temperature dependent. the effective diffusivity values for total solids loss were reduced by the presence of buffer at 40°C but not at 60°C. the effective diffusivity values for soluble pectic substances were not affected by buffer at 40°C but were noticeably lower at 60°C compared to deionized water at the same temperature. the addition of a pectolytic enzyme preparation did not improve the mass transfer of either total solids or soluble pectic substances.     

Assessment of the application of an automated electronic milk analyzer for the enumeration of total bacteria in raw goat milk

Automated electronic milk analyzers for rapid enumeration of total bacteria counts (TBC) are widely used for raw milk testing by many analytical laboratories worldwide. In Ontario, Canada, Bactoscan flow cytometry (BsnFC; Foss Electric, Hillerød, Denmark) is the official anchor method for TBC in raw cow milk. Penalties are levied at the BsnFC equivalent level of 50,000 cfu/mL, the standard plate count (SPC) regulatory limit. This study was conducted to assess the BsnFC for TBC in raw goat milk, to determine the mathematical relationship between the SPC and BsnFC methods, and to identify probable reasons for the difference in the SPC:BsnFC equivalents for goat and cow milks. Test procedures were conducted according to International Dairy Federation Bulletin guidelines. Approximately 115 farm bulk tank milk samples per month were tested for inhibitor residues, SPC, BsnFC, psychrotrophic bacteria count, composition (fat, protein, lactose, lactose and other solids, and freezing point), and somatic cell count from March 2009 to February 2010. Data analysis of the results for the samples tested indicated that the BsnFC method would be a good alternative to the SPC method, providing accurate and more precise results with a faster turnaround time. Although a linear regression model showed good correlation and prediction, tests for linearity indicated that the relationship was linear only beyond log 4.1 SPC. The logistic growth curve best modeled the relationship between the SPC and BsnFC for the entire sample population. The BsnFC equivalent to the SPC 50,000 cfu/mL regulatory limit was estimated to be 321,000 individual bacteria count (ibc)/mL. This estimate differs considerably from the BsnFC equivalent for cow milk (121,000 ibc/mL). Because of the low frequency of bulk tank milk pickups at goat farms, 78.5% of the samples had their oldest milking in the tank to be 6.5 to 9.0 d old when tested, compared with the cow milk samples, which had their oldest milking at 4 d old when tested. This may be one of the major factors contributing to the larger goat milk BsnFC equivalence. Correlations and interactions between various test results were also discussed to further understand differences between the 2 methods for goat and cow milks.     

原料皮真空保藏技术的研究

采用不同的杀菌方法对鲜皮进行处理,而后真空包装保存,考察不同时间生皮的保存状态,目的在于寻找一种简便而清洁的原料皮保藏方法,代替传统的盐腌法,减少盐的污染.试验结果表明鲜皮经紫外线杀菌,喷适量防腐剂后真空包装,在温度约25℃的环境下,可保存约21天,说明原料皮进行真空保藏有一定的可行性.     

氧含量对还原法检测原料乳细菌总数的影响

以还原法理论为基础,以刃天青作为氧化还原试剂,研制原料乳细菌总数快速检测仪器.原料乳中一些成分影响刃天青的颜色变化速度,干扰测定结果.对溶解氧的影响程度进行了判定,结果表明其影响程度较大,不容忽视.     

壳聚糖基纳米氧化锌—丁香精油抗菌复合膜对

将抗菌效果良好且不会产生耐药性的无机抗菌剂纳米氧化锌和具有广谱抗菌性、无毒健康的天然抗菌剂丁香精油加入壳聚糖—魔芋葡甘聚糖复合膜中,研究复合膜对鲜肉的保鲜效果。结果发现：添加质量分数6%纳米氧化锌和体积分数0.6%丁香精油的复合膜对大肠杆菌和金黄色葡萄球菌的抑菌率分别为99.78%,99.06%,具有强抗菌效果;红外光谱分析结果表明壳聚糖官能团和丁香精油中存在的酚反应基团之间有效地发生了键合,且扫描电镜结果表明丁香精油在一定程度上可改善纳米氧化锌的分散效果;添加纳米氧化锌和丁香精油的复合膜对鲜肉的保质期可提高6~8 d。     

Profile of gelatinolytic capacity of raw goat milk and the implications for milk quality

Both endogenous and exogenous proteinases occur in milk, and they can have beneficial or detrimental effects on dairy production. Because the lactation length of dairy goats is shorter and the somatic cell count (SCC) of goat milk is generally greater compared with dairy cows, the objectives of the present study were to investigate the prevalence of major proteinases in raw goat milk, their association with SCC and production stage, and their effects on milk quality. Milk samples were collected from individual goats in consecutive weeks for different durations, covering regular lactation, late lactation, and post-milk stasis. Long-term (monthly) or short-term (weekly) fluctuations of milk fibrinolytic and gelatinolytic capacities of individual goats were revealed chronologically on fibrin and gelatin zymograms, respectively. In a separate trial involving milk samples from 23 goats at random production stages, the percentage of ultracentrifuge force-precipitable casein of total milk protein was calculated to represent milk quality and was assessed to evaluate its correlation with the corresponding proteolytic capacities. The results for regular milk indicate that gelatinase B was more abundant than gelatinase A when they first appeared at SCC of ∼1 × 10⁶/mL. During the last month before milk stasis, both gelatinases A and B were found to be prevalent and prominent in milk regardless of the broad SCC range recorded there. Fibrinolytic activity and the active form of gelatinase A were only regularly detected in post-stasis secretions and were scarce before stasis. The results of the milk quality trial indicate that milk of relatively high proteinase capacity tended to have a low casein ratio. Correlation analysis confirmed a significant relationship between gelatinase capacity of goat milk and production stage, SCC, or casein ratio. It is suggested that an elevation of gelatinolytic capacity of goat milk coincides with an increase in somatic cell number accompanying the extension of lactation length, which is unfavorable for the production of a more desirable quality of goat milk.