冻藏条件对文蛤和波纹巴非蛤组织结构影响的实验研究

以文蛤和波纹巴非蛤贝肉为实验材料,研究了不同的冻藏条件对其组织结构的影响。研究结果表明:在较高冻藏温度下,文蛤和波纹巴非蛤的贝肉组织结构严重变形,适当降低其冻藏温度可以得到较大改善;冻藏时间对文蛤和波纹巴非蛤贝肉组织结构的影响显著;添加抗冻剂后,可以大大减少组织结构的变形,有效改善冻品的品质。实验结果还表明,波纹巴非蛤的耐藏性比文蛤好。     

冻藏条件对文蛤和波纹巴非蛤营养成分影响的实验研究

以文蛤和波纹巴非蛤贝肉为实验材料,研究了不同的冻藏条件对其营养成分的影响。研究结果表明,在较高冻藏温度下,文蛤和波纹巴非蛤的氨基酸损失较大,适当降低其冻藏温度可以较大地提高氨基酸的含量;冻藏时间对文蛤和波纹巴非蛤的氨基酸含量也有显著的影响;添加抗冻剂后,可以大大减少氨基酸含量的损失,有效改善冻品的品质。     

抗冻剂对冻藏文蛤和波纹巴非蛤结构的影响

为了探索抗冻剂对贝肉冻藏品质的影响,以文蛤和波纹巴非蛤贝肉为试验材料,利用组织切片显微拍照法研究了不同的抗冻剂配方对其组织结构的影响.试验表明,不同抗冻剂对改善文蛤和波纹巴非蛤的组织变形的程度是不一样的.糖类与复合磷酸盐的共同作用可更好地改善冻藏品的品质,有效防止组织结构的变形.且糖类与0.4％三聚磷酸钠的作用效果最佳,盐类的添加对文蛤冻品的改善效果优于波纹巴非蛤.     

泠冻对文蛤和波纹巴非蛤组织结构影响的初步研究

利用IMP测温系统及组织切片技术，分别对文蛤和波纹巴非蛤蛤肉在三种冻结方式：-196℃（液氮）、-78℃（干冰）、-18℃（冰箱）中的冻结过程特别是组织结构变化进行了研究。实验结果表明：液氮冻结对蛤肉组织结构的影响最小：对于文蛤是较好冷冻方式，但对波纹巴非蛤却不是最佳的：干冰冻结使组织结构产生的冰晶较为均匀，变形程度次之。冰箱冷冻则使得组织结构严重变形。由此可以认为文蛤是冷冻速率越大、冻结终温越低，冷冻效果越好：而波纹巴非蛤并非如此，它最佳冷冻条件应该处于干冰冷冻和液氮冷冻条件之间。     

广西北部湾主要贝类在冻藏过程中品质变化的研究

测定冻藏过程中牡蛎(Crassostrea rivularis)、文蛤(Meretrix meretrix Linnaeus)和波纹巴非蛤(Paphia Undulata)的水分含量、pH、氨基态氮含量、挥发性盐基氮含量和色差。研究不同的冻藏温度(-18℃和-60℃)和预处理方式(新鲜的和预煮的)对贝肉冻藏品质的影响。结果表明,新鲜的牡蛎、文蛤和波纹巴非蛤在-18℃和-60℃下冻藏3个月,肌肉的水分含量在总体上均呈现下降的趋势;pH的变化起伏不定;氨基态氮和挥发性盐基氮的含量随着冻藏时间的延长而逐渐升高;肌肉亮度降低,总体颜色变暗淡。经过预煮的牡蛎、文蛤和波纹巴非蛤在-18℃或-60℃下冻藏3个月,贝肉的水分含量、pH、氨基态氮和挥发性盐基氮以及亮度变化不大,其品质变化小于未经预煮处理的样品。     

冻藏条件对蛤的蛋白质泠冻变性的影响及其改善的实验研究

以文蛤和波纹巴非蛤为对象研究了不同冻藏条件对肌原纤维Ca^2＋-ATPase活性、盐溶性蛋白溶解度的影响及在相同条件下添加抗冻剂的改善效果。结果表明，冻藏温度对贝肌肉、碎贝肉和贝糜变性有显著影响，且温度越低，变性越小；无完整细胞形态的贝糜的变性幅度最大，碎贝肉次之；添加抗冻剂能有效防止贝肉蛋白质冷冻变性，尤其能使贝糜肌原纤维蛋白质的稳定性大大提高。     

低温条件对波纹巴非蛤营养成分的影响研究

采取常规方法分析常温(25.0℃)和低温(5.0±0.5℃)下波纹巴非蛤(Paphia undulata)的营养成分和氨基酸组成,并对蛋白质进行营养评价,从而分析低温对贝肉成分的影响.结果表明,波纹巴非蛤是一种高蛋白、低脂肪的食品:两种状态下呈味氨基酸和必需氨基酸含量丰富,组成均衡;两种状态下的第一限制氨基酸均为色氨酸.实验表明,波纹巴非蛤是一种优良的蛋白质源.     

文蛤和波纹巴非蛤最佳抗冻剂配方的实验研究

以盐溶性蛋白溶解度、Ca2+ATPase活性和pH值为指标,通过正交实验L9(34)研究,探讨了防止文蛤和波纹巴非蛤蛋白质冷冻变性的最佳抗冻剂配方。实验结果表明,文蛤的最佳抗冻剂配方为焦磷酸钠0.1%、三聚磷酸钠0.1%、蔗糖2%、山梨醇3%;波纹巴非蛤的最佳抗冻剂配方为焦磷酸钠0.1%、三聚磷酸钠0.15%、蔗糖4%、山梨醇3%。在添加最佳抗冻剂后文蛤的Ca2+ATPase活性、盐溶性蛋白溶解度和pH值分别提高了26.4%、25.5%和2%,波纹巴非蛤则分别提高了21%、38.5%和2.5%。     

波纹巴非蛤氨基多糖的分离纯化及其理化性质的初步研究

以波纹巴非蛤全脏器为原料,经酶解、脱色、离心去蛋白、醇沉、干燥等工序得到氨基多糖粗制品(波纹巴非蛤CPG),CPG再经吸附、透析、CTAB络合等方法进行纯化,得到波纹巴非蛤氨基多糖较纯级分(波纹巴非蛤GAG-2)。成分分析表明:波纹巴非蛤GAG-2含有氨基己糖、己糖醛酸、硫酸基和少量的岩藻糖(Fuc)、半乳糖(Gal)。波纹巴非蛤GAG-2经琼脂糖凝胶电泳可再分为F-1、F-2两个级分;红外光谱与CS-6相似;体外抗肿瘤试验表明:0·5mg/mL波纹巴非蛤CPG对HL-60细胞的抑制率可达32·3%,与抗癌药物5-Fu合用时可使抑瘤率提高到56·7%,具显著增敏作用。     

广西北部湾3 种贝类中主要呈味物质的测定及呈味作用评价

测定广西北部湾牡蛎(Crassostrea rivularis)、文蛤(Meretrix meretrix)和波纹巴非蛤(Paphia undulata) 3种贝类中的呈味核苷酸(AMP、GMP、IMP)、糖原等非挥发性呈味物质的含量,并采用味道强度值和等价鲜味值(或味精当量)评价这些非挥发性呈味物质的呈味作用鲜味强度。结果表明：牡蛎、文蛤和波纹巴非蛤的味精当量分别为3.2、1.9、2.7g MSG/100g,对应的味精当量的味道强度值分别是106.7、63.3、90,均远大于1,是其呈强烈鲜味的主要原因。     

冻结速率和冻藏温度对文蛤蛋白质冷冻变性的影响

利用IMP热电偶测温系统，对文蛤分别在-18℃和-30℃冻结温度下的冻结过程进行了测量，对-18℃和-30℃下3种贮藏形态的贝肉冻结样品和冻藏样品肌原纤维蛋白的Ca~(2+)-ATPase活性、Mg~(2+)-ATPase活性、盐溶性蛋白溶解度及添加抗冻剂后防止其冷冻变性的影响进行了研究。结果发现，冻结对贝肉蛋白质变性影响不大，冻藏使蛋白质发生显著的变性，温度低的变性小；在贮藏贝肉的3种形态中，无完整细胞形态的贝糜的变性幅度最大，碎贝肉次之，贝肌肉形态的保持得较好；添加抗冻剂能有效防止贝肉蛋白质冷冻变性，尤其能使贝糜形态贝肉蛋白质的稳定性大大提高。     

花蛤净化前后主要营养成分及鲜味氨基酸的比较

本文对花蛤净化前后的营养成分进行了测定,包括灰分、水分、粗脂肪、粗蛋白、氨基酸。实验结果表明:净化前后,除粗脂肪外,花蛤样品的各营养成分并无明显差别,对鲜味有影响的特征性氨基酸(谷氨酸和天门冬氨酸)以及对甘味有影响的特征性氨基酸(丙氨酸和甘氨酸),在净化前后也没有明显的变化,因而得出净化对花蛤的营养成分无显著影响,而净化可以降低大肠杆菌和沙门氏菌等致病菌数量。所以对贝类进行净化是势在必行的。     

Percentages of protein and nonprotein nitrogen with varying fat and somatic cells in bovine milk

Over 15 mo, 28,390 individual milk samples from 3,600 cows in 62 Quebec Holstein herds were analyzed for crude protein, true protein, nonprotein nitrogen, fat, and somatic cell counts. Unadjusted means with standard errors were 3.51% +/- .002, 3.31% +/- .002, 31.70 mg/100 ml +/- .12, 3.67% +/- .004, and 297,230 cells/ml +/- 4002. Nonprotein nitrogen as a percentage of total nitrogen was 5.57% +/- .02. Least squares analyses showed significant effects of herd, age of cow, month of test, stage of lactation, somatic cell count, and fat percentage on contents of crude protein, true protein, and ratio of nonprotein nitrogen to total nitrogen. Highly variable nonprotein nitrogen fraction content during different months of the year and various stages of lactation is responsible for changes of crude protein content whereas changes of crude protein for different ages of cows, fat, and somatic cells in milk are due to changes of true protein content. Automatic infrared instrument calibrated against crude protein standards can be used satisfactorily to measure crude protein in milk if variations are due to age of cow, fat, and somatic cell counts. However, the instrument becomes inaccurate for measuring large variation of crude protein caused by variability of nonprotein nitrogen due to season and stage of lactation.     

Effect of Foliar Application of Auxin on the Quality of Potatoes

Katahdin and Kennebec potatoes were sprayed with 10^?5M auxin at the beginning of flowering. Tubers from the auxin-treated plants were compared with untreated controls for phenolic content, enzymatic discoloration, total nitrogen, nonprotein nitrogen, free ammo acids, lipids, minerals, and ascorbic acid content. In both varieties auxin increased the phenols and enzymatic discoloration. However, no differences were observed in fatty acid composition and ascorbic acid content. Total nitrogen, nonprotein nitrogen, free amino acids, crude lipid, phospholipid and magnesium content were higher, and iron lower, in Katahdin tubers from the treated plants.     

Relationship between ruminal ammonia and nonprotein nitrogen utilization by ruminants. I. Development of a model for predicting nonprotein nitrogen utilization by cattle.

The influence of ration composition on mean ruminal ammonia concentration was studied by collecting samples of ruminal ingesta from cattle fed rations varying in crude protein and total digestible nutrient content. A minimum of four sampling times distributed throughout the day permitted calculation of mean ruminal ammonia concentrations. Mean ruminal ammonia concentration was positively related to dietary crude protein concentration and negatively related to total digestible nutrient concentration. It is postulated that mean ruminal ammonia concentration may be a useful criterion for predicting efficacy of nonprotein nitrogen supplementation. A quantitative approach for evaluating nonprotein nitrogen supplementation based upon determination of the point at which ruminal ammonia exceeds the requirement (5 mg ammonia nitrogen/100 ml rumen fluid) of the ammonia-utilizing bacteria is proposed. Dietary conditions expected to result in excessive concentrations of ruminal ammonia are defined and recommended upper limits for nonprotein nitrogen supplementation are presented. Theoretical relationships between composition of the unsupplemented ration, amount of nonprotein nitrogen added, and efficiency of nonprotein nitrogen utilization are discussed. The practice of adding nonprotein nitrogen so as to exceed 12 to 13% crude protein in typical dairy or feedlot rations needs to be reevaluated.