Characterisation of trypsin purified from the viscera of Tunisian barbel (Barbus callensis) and its application for recovery of carotenoproteins from shrimp wastes

Trypsin was purified from the viscera of barbel by precipitation using ammonium sulphate (0-80%), Sephadex G-100, and Mono Q-Sepharose ion exchange chromatography. The trypsin was purified 27-fold, with 79 U/mg specific activity and 31% recovery. The enzyme had a molecular weight of 24 kDa; purified trypsin appeared as a single band on native-PAGE. The optimum pH and temperature for enzyme activity were pH 10.0 and 55 °C with BAPNA used as a substrate. The N-terminal amino acid sequence of the first 12 amino acids of the purified trypsin was IVGGYECTPYSQ. The Michaelis-Menten constant (K_m) and catalytic constant (k_cat) values of the enzyme were 0.018 mM and 1.21 s⁻¹, respectively. The study also investigated the effects of purified trypsin on the recovery of carotenoproteins from shrimp (Parapenaeus longirostris) shells through hydrolysis using 1.0 U barbel trypsin/g shrimp shells for 1 h at 30 °C. The freeze-dried carotenoproteins recovered contained 71.09% protein, 16.47% lipid, 7.78% ash, and 1.79% chitin.     

加工食品中虾蟹类过敏原ELISA检测前处理方法的研究

目的建立了一种可应用于加工食品中虾蟹类过敏原检测的前处理方法。方法针对提取液和提取步骤2个部分选取条件先后进行优化,通过对相应样品提取后的蛋白溶出量等进行评估,选取最适合本ELISA检测的条件。结果采用含有0.5%SDS和0.5%DTT的磷酸盐缓冲液(pH 8.5),按照食物样品与提取液的1:9 (m/V)进行混合,在室温下均质30 min,3020×g离心15 min,取上清液进行检测效果最佳,此方法与PBS(pH7.4)溶液提取方法相比,蛋白质溶出量增加了约5倍。结论在已建立的检测虾蟹类过敏原夹心ELISA的基础上,建立优化前处理方法进一步提高了加工食品中过敏原的提取率。     

Purification and characterization of a novel thermostable phytase from the thermophilic Geobacillus sp. TF16

A novel phytase from thermophilic Geobacillus sp. TF16 was puri?ed approximately 5-fold using ammonium sulfate precipitation and ion exchange chromatography, and determined as a single band 106.04 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Optimum temperature and optimum pH were found to be 85°C and 4.0, respectively. The enzyme is highly thermostable and V_max and K_m values were calculated as 526.28 U/mg and 1.31 mM, respectively. It was also found that the enzyme exhibited a broad substrate selectivity and resistance toward proteases and effectively hydrolyzed soymilk phytate. These results suggest that this study provides an alternative phytase enzyme with enhanced properties.     

活性染料净洗剂Dekol S应用实践

Ｄｅｋｏｌ Ｓ属阴离子型聚合物,对各种酸,碱类以及非离子助剂在染液的常用浓度下十分稳定,与阴离子和非离子性助剂相容性良好,经车间大样试产了１０万米左右印花布,均无发生地沾污而需回修的问题,各项色牢度指标均符合标准。     

废纸化学残留物清除剂产品研制及应用

简介了一种具有广普效果的废纸化学残留物清除剂产品配方的主要化学组成及小型试验结果,重点叙述了新产品产业化生产应用时的工艺技术条件及影响因素。     

提高印花织物净洗工艺

为了防止印花织物的白地和白花沾色现象,提高印花织物的色泽鲜艳度和皂洗牢度,织物印花后必须使用净洗剂进行皂煮,以去除浮色及浆料。文章通过对各种净洗剂的对比试验,认为国产防沾污剂S—2是目前较理想的防沾污净洗助剂。     

N,O-Carboxymethyl Chitosan: An Innovation in New Natural Preservative from Shrimp Shell Waste with a Nutritional Value and Health Orientation

This research has been done to modify chitosan into its derivatives, i.e. N,O-Carboxymethyl Chitosan. The characterization of chitosan and N,O-Carboxymethyl Chitosan, which includes analysis using FTIR, SEM, and XRD, showed that the a natural preservative N,O-Carboxymethyl Chitosan had formed. Our data indicated that addition of N,O-Carboxymethyl Chitosan to samples of chicken meat could be regarded as a solution to increase fiber contents, resilience of food storage, and stability of nutrients (lowering levels of dry substances), lower ash contents, increase protein contents, keep fat contents, as well as increase levels of Nitrogen-Free Extract. Therefore, we conclude that the N,O-Carboxymethyl Chitosan can be used as a preservative which also orients towards nutritional values and health.     

洗涤剂用酶的研究与开发──新型碱性脂肪酶

讨论了碱性脂肪酶的性质、生产及其在洗涤剂中的应用     

洗涤剂去污力测定用污布的开发

介绍一种新开发的洗涤剂去污力测定用血－奶－印度墨水／棉型人工污布     

Evaluation of detergent extraction procedures for characterising carbohydrate components in ruminant feeds and digesta

Steers fitted with simple rumen and abomasal cannulas were given isoenergetic diets of approximately equal amounts of untreated (UT) barley straw and concentrates (flaked maize + tapioca) alone (BS) or with urea (BSU) or fishmeal (BSF). Similar diets were also given in which the barley straw had been treated (AT) with NaOH (BSA, BSAU and BSAF respectively). The diets were given in a 6 × 6 Latin square design. Feed components and abomasal digesta samples were analysed for neutral (NDF) and acid (ADF) detergent fibres and for monosaccharide constituents of structural polysaccharides. Hemicellulose contents were estimated as the sum of xylose + arabinose (X + A) and by the difference between ash-free NDF and ash-free ADF (NDF-ADF). Cellulose was estimated as β-linked glucose (C) and by the difference between ash-free ADF and lignin (ADF–L).¹⁰³ Ruthenium and PEG were given as flow markers and flows (g24h^?1) at the abomasum of carbohydrate components estimated in these ways were calculated. Approximately 98% (by wt.) of the cellulose (C) found in original feed and digesta samples was recovered in both NDF and ADF. Recoveries of hemicellulose (X + A) in NDF from UT straw, AT straw and abomasal digesta were approximately 92, 48 and 50%, respectively. The ADF fraction of feeds and digesta contained 3–6 and 10–17% of the nitrogen and xylose, respectively, present in the original samples. Mouth to abomasum digestibilities of hemicellulose (NDF– ADF) for diets BS, BSU, BSF, BSA, BSAU and BSAF were 39, 62, 67, 29, 61 and 76%, respectively. Corresponding values for cellulose (ADF–L) were 37, 34, 50, 45, 48, and 63%, respectively. The use of NDF–ADF and ADF–L as measures of hemicellulose and cellulose contents, respectively, of feeds and digesta, and the digestibility of these carbohydrate fractions between mouth and abomasum of steers are discussed.     

草鱼内脏油的精制及阻抑鱼油氧化条件的研究

目的:研究草鱼内脏油精制条件,并比较不同抗氧化剂对鱼油的抗氧化作用.方法:用真空提油法提取粗草鱼内脏油,通过脱胶、脱酸、脱色、脱臭工艺精制鱼油,以过氧化值(POV)和硫代巴比妥酸值(TBARS) 为指标,在60℃条件下,对VC、VE、BHT、PG四种抗氧化剂进行筛选并比较.结果与结论:最佳的精制条件为:利用50%的磷酸脱胶,添加量为油量的1%;用浓度为3.65%的氢氧化钠脱酸,添加量为油量的1.5%;用活性炭和活性白土脱色,二者比例为1:20,添加量为油量的2.1%;在真空度为0.085kPa的条件下脱臭,时间为60min.不同抗氧化剂对鱼油的抗氧化能力为:0.01% PG ＞0.02% BHT＞0.1% VE＞0.2% VE＞0.2% VC.     

不同来源脂肪酶的催化反应性质比较

研究了三种脂肪酶的催化反应性质,包括水解作用pH、温度适宜范围,酶的酸碱稳定性和热稳定性,酶催化水解作用的底物脂肪酸特异性和酯键位置特异性,及对逆向反应的催化作用等。对三种酶的催化反应的机制进行了比较和讨论。     

畜禽肌肉、内脏及虾中磺胺二甲嘧啶残留量的检测技术研究

为了快速、简便、灵敏地监测畜禽肌肉、内脏及虾中的磺胺二甲嘧啶残留,建立了高效液相色谱法快速检测技术。动物组织中的磺胺二甲嘧啶用二氯甲烷超声提取3次,提取液与2％硫酸钠水溶液进行液一液分配,下层有机相经脱水、浓缩后用0．02mol／L盐酸溶解浓缩瓶中残留物,以正己烷去除脂溶性杂质,经0．45μm滤膜过滤后供HPLC测定。结果表明本方法的线性范围为0．2～3．0μg/mL,方法的最低检出浓度为2．1μg/kg,在50～100μg/kg的加标水平,方法平均回收率为76．6％～93．6％,相对标准偏差为4．4％～8．4％。该方法适用范围广,回收率高,检测限低,简单易行,易于在基层推广应用。     

龙虾片挤压食品研究

本文对龙虾片的蒸煮挤压工艺进行了探索性的研究,发现在挤压机筒温度T_b=90℃,挤压螺杆旋转速度V_s=78r/min,绝对干料进料速度V_F=150g/min~(-1)以及物料水分含量M_c=50%的工艺条下,可以生产出品质优良的龙虾片。本文还就龙虾片的油炸膨化机理进行了讨论。     

Use of viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus) for the production of protein hydrolysate from toothed ponyfish (Gazza minuta) muscle

Proteolytic activity of viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus) was studied. The optimal pH and temperature were 9.0 and 50 °C, respectively, when toothed ponyfish (Gazza minuta) muscle was used as a substrate. When viscera extract from hybrid catfish was used for the production of protein hydrolysate from toothed ponyfish muscle, extract concentration, reaction time, and fish muscle/buffer ratio affected the hydrolysis and nitrogen recovery (NR) (p < 0.05). Optimum conditions for toothed ponyfish muscle hydrolysis were 3.5% hybrid catfish viscera extract, 15 min reaction time and fish muscle/buffer ratio of 1:3 (w/v). High correlation between the degree of hydrolysis (DH) and NR (R² = 0.974) was observed. Freeze-dried hydrolysate had a high protein content (89.02%, dry weight basis) and it was brownish yellow in colour (L^∗ = 63.67, a^∗ = 6.33, b^∗ = 22.41). The protein hydrolysate contained a high amount of essential amino acids (48.22%) and had arginine and lysine as the dominant amino acids.     

虾头水解蛋白脱苦脱腥方法的研究

为去除虾头水解蛋白溶液的苦腥味,比较了粉末活性炭吸附法、酵母发酵法和环状糊精包埋法的脱苦脱腥效果。结果表明,酵母发酵与β-环糊精包埋联合去除苦腥味的效果最佳。通过添加1.5%的β-环糊精,60℃包埋60min,然后添加1%的酵母,在40℃下恒温发酵60min,离心分离后沸水浴5min。处理后的虾头水解蛋白液无苦腥味,且具有浓郁的鲜虾风味。     

Compositional characteristics of muscle and visceral oil from steelhead trout and their oxidative stability

The quality of lipid from steelhead trout viscera, a byproduct of steelhead trout industry, was evaluated and compared with that of the muscle. Steelhead trout viscera had a higher lipid content than muscle and the visceral oil differed from muscle oil in its lipid class composition. Neutral lipids, mainly triacylglycerols (TAG), comprised the major lipid class in both muscle and visceral lipid. However, as expected, muscle contained a remarkably higher level of phospholipids (PL) than viscera, and the ratio of total neutral lipids to polar lipids was lower in muscle than in viscera. Visceral and muscle lipid had similar fatty acid compositions, with the concentration of muscle polyunsaturated fatty acids (PUFA) slightly higher than that of visceral PUFA. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were the major n-3 PUFA present in both muscle and visceral lipid; docosapentaenoic acid (DPA) was present at about 1.61–1.76%. With respect to minor components, muscle lipid had higher α-tocopherol and total carotenoids contents than visceral lipid. Oxidative stability of visceral and muscle lipid, as determined by conjugated dienes (CD) and thiobarbituric acid reactive substances (TBARS), showed that visceral lipid was more stable against oxidation than muscle lipid, probably due to their different lipid profiles. Besides, carotenoids, which were present more abundantly in muscle, might have acted as prooxidants and therefore, decreased the oxidative stability of muscle lipid. These results suggest that steelhead trout viscera may serve as a good source of lipid and could be utilized for production of omega-3 oils.     

脂肪酶解聚壳聚糖及其衍生物的研究

壳聚糖及其衍生物能很容易被脂肪酶解聚。当壳聚糖乳酸盐溶液与脂肪酶在２５℃下作用１０ｍｉｎ后,其溶液粘度被降低到初始值的３５％,分子量从约７００ｋＤａ减少到１３ｋＤａ（还原糖滴定法测定）。脂肪酶浓度在４．５×１０－３～９×１０－１ｇ／Ｌ范围内,解聚初速度与酶浓度成对数线性关系。Ｎ－羧甲基壳聚糖比壳聚糖更容易被脂肪酶解聚。     

Effect of detergents in the release of bisphenol A from polycarbonate baby bottles

Bisphenol A (BPA) is a monomer crucial for the production of polycarbonate (PC). Recently, it has been verified that BPA is able to migrate from PC baby bottles into food simulants and numerous studies indicate that BPA may affect human health.In this work, five different detergents and bleach were tested to verify if they were able increasing the BPA release from the PC. High performance liquid chromatography (HPLC) with fluorescence detection (FLD) and gas chromatography coupled to mass spectrometry (GC–MS) were used to quantify and identify BPA. Of all detergents tested, only with one was not detected a BPA concentration higher than the control. In the worst case, BPA levels detected were about 500 times higher than the control and the concentration kept high even after rinsing the PC samples three times. In the case of bleach, while it was in contact with the PC, the BPA released was not detected.