Effect of soaking with hydrogen peroxide and carbonate/bicarbonate buffer solutions on chemical composition and protein extractability of desalted cod

Cod salted with various combinations of NaCl, KCl, MgCl₂ and CaCl₂ were soaked for the first 24 h with a 0.2 M carbonate buffer solution (pH 9.5) or for the first 5 h with 1% hydrogen peroxide (pH 7.16). Chloride, ions and ash content in muscle were measured during the soaking process. After soaking, the composition of soluble muscle protein extracted in NaCl 0.86 M was determined by SDS-PAGE. The divalent, cation content was not affected by the salting and soaking processes. The protein extractability was low, especially when H₂O₂ was used. The use of alkaline buffer solution produced better protein functional quality. When the alkaline solution was used for soaking, the soluble fraction was constituted of a larger variety of proteins. Actin was soluble only when MgCl₂ and KCl were used for salting and the alkaline solution for soaking. The use of carbonate/bicarbonate buffer solution for soaking could therefore be useful to improve the functional quality of muscle protein of desalted cod.     

Efficacy of non-thermal technologies and sanitizer solutions on microbial load reduction and quality retention of strawberries

The effect of non-thermal technologies (ozone in aqueous solution, ultrasound and ultraviolet C radiation) and washings with chemical solutions (sodium hypochlorite and hydrogen peroxide) on safety and quality features of strawberries was studied. These treatments were applied before fruit storage at two different temperatures (4 and 15 °C). The overall impact on microbial loads (total mesophiles, and yeasts and moulds) and selected quality attributes (colour, firmness, pH, total anthocyanins and ascorbic acid content) was assessed.During storage under refrigerated temperature, washing with hydrogen peroxide solutions resulted in strawberries with lower microbial loads, when compared to the other treatments. However, it produced significant key quality attributes losses, such as colour and total anthocyanins content.The results presented show that ozone and ultrasound are promising alternatives to thermal treatments. The application of such technologies, before refrigerated storage of strawberries, allowed a satisfactory retention of all quality characteristics analysed, while being efficient in controlling microbial contamination.     

紫羊绒无磷脱色工艺研究

以紫羊绒为原料,利用无磷双氧水稳定剂作为含磷稳定剂的替代物,对紫羊绒进行脱色。通过探讨稳定剂种类、稳定剂用量等单因素的影响,并选出4个主要因素硫酸亚铁用量、双氧水用量、氧化漂白pH值和柠檬酸钠用量进行正交试验,以脱色紫羊绒白度提高量和单纤维强力下降率为主要测试指标,优化紫羊绒无磷脱色工艺。结果表明,紫羊绒无磷脱色工艺:硫酸亚铁用量4.5 g/L,双氧水用量70.4 mL/L,氧化脱色pH值为9.5,柠檬酸钠用量16.9 g/L,预处理时间2.0 h,浴比1∶13;采用该工艺处理紫羊绒纤维的白度可提高33.26%,纤维强力下降率0.35%,且可生化降解性好,BOD5/COD(铬法)=2.74。     

Effects of potassium buffers on feed intake in lactating dairy cows and on rumen fermentation in vivo and in vitro

Twenty-four Holstein cows were used to compare acceptance of concentrates and complete rations containing 1) no buffer, 2) 1.8% potassium bicarbonate, 3) 1.2% potassium carbonate, or 4) 1.5% sodium bicarbonate in the concentrate. When concentrate and a forage blend were offered separately (comparison period 1), concentrate intake did not differ among treatments, but forage blend consumption and complete ration intake was greater with the potassium carbonate ration (comparison period 2). Rumen pH did not differ, but urine pH was higher in cows fed complete rations containing buffers. Cows fed potassium carbonate had higher milk fat percentages than cows fed sodium bicarbonate during the first comparison period and higher than controls during the second comparison period and produced more 3.5% fat-corrected milk and solids-corrected milk than cows fed sodium bicarbonate in both comparison periods. Milk protein percentage was lower in cows fed potassium carbonate diets as compared with those fed sodium bicarbonate diets, but total protein production was similar. In three continuous culture in vitro trials, potassium carbonate maintained fermenter pH comparably to sodium bicarbonate, and total volatile fatty acid and acetate production were similar.     

过硫酸氢钾复合盐在印度发漂白工艺中的应用

采用过硫酸氢钾复合盐复合过氧化氢对印度发进行漂白,考察过硫酸氢钾复合盐质量浓度、pH、时间、温度对印度发白度和断裂强力的影响。结果表明:过硫酸氢钾复合盐复合过氧化氢的漂白效果较传统过氧化氢漂白有了很大的提升,白度和断裂强力明显提高。     

采后过氧化氢处理对伽师瓜贮藏品质的影响

以新疆伽师瓜为实验材料,研究冷藏(6±1)℃条件下,不同浓度H2O2处理结合处理后套袋对伽师瓜果实采后贮藏品质的影响。结果表明：贮藏期间,过氧化氢处理可明显延缓伽师瓜硬度下降,降低呼吸、乙烯高峰和贮藏过程中的水分损失,减缓可溶性固形物及VC含量的消耗,而处理后套袋可明显延迟呼吸和乙烯高峰。可见处理保持了贮藏期伽师瓜的品质,有利于伽师瓜的贮藏。综合比较,4% H2O2处理后结合套袋对伽师瓜贮藏期品质保持的效果最佳。     

羊毛漂白工艺研究

在单因素实验的基础上,采用正交试验首先对比分析了羊毛过氧乙酸漂白和保险粉漂白工艺.结果表明,漂白液的pH值是影响漂白后纤维白度的主要因素,次要因素是温度,采用过氧乙酸漂白可以获得较高的白度.对比分析了采用过氧化氢一柠檬酸漂白工艺和过氧化氢一尿素漂白工艺后羊毛纤维的白度和碱溶率.结果表明,漂白液的pH值是影响漂白后羊毛白度和碱溶率的主要因素,漂白温度次之.漂白液中含有过氧化氢时漂白后纤维白度、碱溶率等指标更好,其中过氧化氢一柠檬酸漂白工艺对纤维的损伤较小,白度更高.     

Effects of potassium carbonate and sodium bicarbonate on rumen function in lactating Holstein cows

Twelve multiparous lactating Holstein cows were used to compare effects of 1) no buffer, 2) 1.5% sodium bicarbonate, 3) 1.25% potassium carbonate, or 4) 1.85% potassium carbonate in total diet on rumen environment and liquid turnover, dry matter intake and digestibility, milk yield and composition, and blood acid-base balance. Cows fed buffered diets had greater dry matter intake and greater digestibility of dry matter, acid detergent fiber, and neutral detergent fiber than controls. Rumen pH was higher in cows fed buffers than in controls 2 to 4 h postfeeding, but buffered diets were not different. Rumen volume, osmolality, and liquid turnover were unaffected by dietary treatment. Molar percentage of rumen acetate was greater, propionate was less, and acetate:propionate ratio was greater in cows fed 1.85% potassium carbonate compared with other treatments. There were no treatment effects on milk yield, although milk fat percentage tended to be greater in buffered diets. Blood acid-base balance was not altered. Cows fed diets containing potassium carbonate performed similarly to those fed sodium bicarbonate. No adverse effects of potassium carbonate on rumen function or environment were observed. Potassium carbonate is an acceptable buffer and serves as a potassium supplement.     

Effect of Osmotic Dehydration and Pectin Edible Coatings on Quality and Shelf Life of Fresh-Cut Melon

The aim of this work was to investigate the influence of osmotic dehydration and pectin edible coating on quality parameters of fresh-cut melon. Fruits were osmodehydrated in 40°Bx sucrose solution containing 0.5% calcium lactate or dipped in 0.5% calcium lactate solutions. Then, samples were coated with 1% pectin. Melon pieces dipped in sanitizing solution (nontreated sample) were used as control. Weight loss, respiration rate, firmness, color parameters (lightness, chroma, and whiteness index), sensory acceptance, microbial growth, and structural changes of fruits were evaluated during storage at 5 °C for 14 days. The shelf life of the control sample was limited to 9 days due to microbial growth and sensory rejection, while treated samples showed a shelf life of 14 days. Higher preservation of firmness in coated samples was attributed to the action of calcium salt on melon structure, causing a strengthening of the cell wall. Calcium lactate also inhibited microbial growth along storage, improving microbiological stability of fresh-cut melon. The use of calcium lactate dips and pectin edible coatings hindered weight loss and maintained fruit color characteristics during the storage time. However, these pretreatments probably masked melon taste, reducing the sensory acceptance scores at the end of shelf life study. The combination of osmotic dehydration and pectin coatings was a good preservation alternative for fresh-cut melon, since it improved fruit sensory acceptance, promoting the reduction of product respiration rate, as well as the maintenance of quality parameters during 14 days.     

大豆蛋白复合纤维的漂白和增白工艺

采用双氧水和还原剂DOTU对大豆蛋白复合纤维进行氧化和还原漂白，对漂白剂浓度、pH值、温度等因素进行试验，根据漂白纤维的白度、失重率、蛋白质含量保持率等指标优选漂白生产工艺；筛选棉用荧光增白剂，并制订磁白工艺，以进一步提高大豆蛋白复合纤维的白度。     

非硅酸盐系双氧水漂白稳定剂PST的研制及应用性能

采用多种有机螯合剂与无机盐等复配成双氧水稳定剂PST，测试了其分解率，白度，毛效和手感，并与水玻璃作了比较，试验结果表明：稳定剂PST性能优良，对双氧水稳定效果好，能使织物获得较好的白度，毛效和手段，且成本不高，操作简便，是理想的双氧水漂白稳定剂。     

蚕蛹蛋白纤维过氧化尿素漂白研究

比较蚕蛹蛋白纤维过氧化尿素和过氧化氢漂白的H2O2消耗速率、pH值变化、白度和失重率,结果表明,过氧化尿素的漂白效果优于过氧化氢。     

PROPERTIES OF FRANKFURTERS PROCESSED WITH POTASSIUM AND SODIUM BICARBONATE

A study was designed to evaluate the use of low levels of sodium (0.25, 0.5, 1%) and potassium (0.25, 0.5%) bicarbonate on the sensory, microbial and functional properties of frankfurters. Both sodium and potassium bicarbonate resulted in higher pH values than control (no bicarbonate) on day 0 but differences diminished after storage at 4°C for 22 days. At the 0.5% level of addition, both sodium and potassium bicarbonate treatments had lower percent free water when compared to controls. The addition of high levels of bicarbonate resulted in diminished sensory properties; however, low levels had sensory characteristics in the acceptable range. No differences were detected between treatments for aerobic plate counts, anaerobic plate counts or yeast and mold counts. Results indicate an acceptable product can be produced using low levels of either sodium or potassium bicarbonate. The use of low levels of bicarbonate also results in beneficial changes of some physical properties.     

Hydrogen Peroxide Production by Lactobacillus delbrueckii Subsp. Lactis I at 5°C

Cells of Lactobacillus delbrueckii subsp. lactis I produced hydrogen peroxide at 5°C in sodium phosphate buffer (0.2M, pH 6.5) with or without glucose. However, if the cells were starved by preincubation in buffer alone, glucose or sodium lactate were necessary to cause hydrogen peroxide production at 5°C. Hydrogen peroxide production by nonstarved cells was confirmed to be in part due to a NADH oxidase. The production of hydrogen peroxide by starved cells in buffer plus glucose in the early stage of incubation was associated with the production of a small portion of lactic acid which disappeared upon further incubation. Additional experiments revealed that hydrogen peroxide was produced in buffer containing sodium lactate added in place of glucose. Results suggested the presence of a lactate oxidase in the organism which used D-lactate to produce hydrogen peroxide.     

棉针织物冷轧堆炼漂工艺影响因素分析

探讨了棉针织物冷轧堆炼漂工艺的冷堆时间、精炼剂用量、烧碱用量、双氧水用量、双氧水活化剂用量等因素对双氧水分解率及棉针织物白度的影响。结果表明:提高冷轧堆炼漂工艺双氧水有效利用率和棉针织物白度的最佳方式是提高平幅精炼剂DM-1346N的用量,其次分别是提高烧碱用量、延长堆置时间和提高双氧水用量;另外,在配方中加入一定量的双氧水活化剂也可以提高双氧水的有效利用率,进一步提升白度。     

氧化和还原漂白对大豆纤维结构性能的影响

还原漂白的大豆纤维白度和失重率很低，还原漂白对大豆蛋白含量和微细结构无影响、对可染性的影响很小。在氧化漂白中，亚氯酸钠和双氧水／四乙酰乙二胺(反应生成过乙酸)的漂白效果很好；亚漂纤维的失重率高、大豆蛋白含量降低较大，漂白时大豆蛋白的流失极大地降低了可染性；双氧水/四乙酰乙二胺和双氧水漂白的纤维失重率低、大豆蛋白含量稍有降低，两者(尤其是前者)对碱性和羟基氨基酸的可能的氧化作用导致了可染性的降低。氧化和还原漂白对纤维的结晶特性几乎无影响。     

牦牛肺中肝素钠提取工艺条件优化

肝素钠在牛肺中主要以粘多糖-蛋白质复合物的形式存在,本文采用酶解方法解离牦牛肺,之后采用酶解结合过氧化氢氧化法法对肝素钠进行精制;使用天青A比色法测肝素钠效价;通过L9(34)正交试验确定其最佳提取工艺条件为:木瓜蛋白酶1:500、酶解时间3h,胰蛋白酶1:200,过氧化氢1%。条件优化后产品效价为131U/mg,产率可达1.92%。     

丙烯腈基酪素蛋白复合纤维漂白的方法

分别采用双氧水、双氧水／四乙酰乙二胺（TAED）和保险粉对丙烯腈基酪素蛋白复合纤维进行漂白，比较了三种漂白剂漂白后纤维的白度、失重率、酸性染料可染性、化学和结晶结构。研究表明，采用保险粉在中性条件下漂白，可改善纤维白度，酪素蛋白没有流失，可染性不受影响；双氧水/TAED漂白，其纤维白度最高，酪素蛋白的流失极低，但可染性受到一定程度的影响；双氧水碱性漂白引起酪素蛋白的大量流失，明显降低了可染性，但纤维因聚丙烯腈变性而泛黄。三种漂白方法均未改变纤维的主体结晶结构。     

棉短绒制绒毛浆H2O2-氧碱蒸煮工艺

介绍了棉短绒制绒毛浆的H2O2—氧碱制浆工艺，对比研究了原料预处理及添加Na2CO3对棉绒制浆得率、纸浆白度及吸水高度的影响。     

大豆纤维用双氧水/四乙酰乙二胺活化体系漂白

采用在溶液中使双氧水／四乙酰乙二胺(TAED)按反应的理论摩尔比就地生成过乙酸的方法对大豆纤维进行漂白，在30％双氧水7．5～10g／L、TAED／过氧化氢摩尔比0．5、pH5～6、70～80℃的条件下，可获得良好的漂白效果，亨特白度可达80。大豆纤维漂白后，其主体结构未发生变化，大豆蛋白含量略微降低，极性氨基酸被部分氧化导致了酸性染料可染性明显降低。这种新方法漂白的白度高与过乙酸是强氧化剂和大豆纤维不含酪氨酸有关。