Changes in Concentration of Certain Elements During Maturation of Muscadine Grapes (Vitis rotundifolia)

Changes in percent ash and certain elements were followed during maturation of berries of two cultivars of muscadine grapes (Vitis rotundifolia). Analyses were done on deseeded berries. Percent ash increased significantly during maturation of Carlos berries, but did not increase significantly during maturation of Noble berries. Potassium was the element in highest concentration in both cultivars during maturation and at harvest. Potassium, calcium, phosphorus, and sodium were the major elements found to be significantly correlated with maturation and were found in concentrations similar to those reported in the literature for V. vinifera grapes. Iron, copper, zinc, and manganese were minor components. Four additional muscadine cultivars, sampled only at full maturity, had similar concentrations of elements to those found in ripe berries of Carlos and Noble. The averaged values of ash (%) and elements (ppm) for all six cultivars when sampled at their normal harvest dates are: ash = 0.57; Na = 58.6 (Carlos and Noble only); P = 99.6; K = 1641.0; Ca = 124.2; Mg = 59.2; Mn = 7.2; Cu = 0.5; Zn = 0.5; Fe = 3.0.     

醋豆加工过程中物质含量的变化及醋豆产品的感官评价

研究了大豆在醋制过程中物质含量 (包括总酸含量和游离氨基酸含量 )的变化 ,对醋豆产品的感官评价做了分析。结果表明 ,在 3 5mg/mL的白醋和米醋中 ,生豆和熟豆含酸量在开始的 12h内快速增加 ,浸渍醋液的含酸量则快速下降 ,从 2 4h以后 ,豆子的含酸量和浸渍醋液的含酸量都趋于恒定 ;在 3 5～ 8 5mg/mL的白醋中浸渍 ,醋液浓度对醋豆含酸量有明显的影响。生大豆和煮熟大豆的游离氨基酸含量存在较大差异 ,生豆在渍米醋 4 8h以后、熟豆在渍米醋 10h以后 ,其游离氨基酸含量都趋于恒定。含酸量在质量分数 0 6 %左右的熟豆醋豆产品 ,在色泽、气味、硬度、酸度、豆香味及综合评分等方面能为消费者所接受     

Free Amino Acids and Other Nitrogenous Fractions in Wine Grapes

SUMMARY: The concentration of eight free amino acids, total nitrogen, amino-acid fraction nitrogen, and nonamino-acid-fraction nitrogen in the juices of 26 red- and 23 white-wine varieties of grapes was determined at early and late stages of fruit maturity. Proline was the most prominent amino acid in 31 of the varieties at early harvest and in 45 of the varieties at late harvest while arginine was the main amino acid in 16 and 3 varieties at early and late harvest, respectively. "Salvador" and "Scarlet" were the only varieties in which α-alanine was the predominant amino acid. The concentration of total nitrogen in the juices of the various varieties ranged from 44 to 256 mg/100 ml and the amino-acid fraction nitrogen ranged from 26 to 171 mg/100 ml juice. The amino acid fraction and nonamino acid fraction nitrogen in the juices ranged from 53 to 76% and 23 to 56% of total Kjeldahl nitrogen respectively. Alanine, γ-aminobutyric acid, arginine, aspartic acid, glutamic acid, proline, serine and theronine accounted for 29 to 72% of the total nitrogen and 47 to 96% of the amino acid fraction nitrogen. Arginine contributed the most nitrogen of the amino acids, accounting for 6 to 44% of the total nitrogen in the juices of the various fruits.     

妙府老酒中总氮及氨基酸含量的测定

分别采用凯式定氮法、隆丁区分法与全自动氨基酸分析仪分析测定了妙府老酒中的总氮、蛋白质分子质量分布及氨基酸含量。结果表明,妙府老酒氨基酸总含量为3287.52 mg/L,是富含氨基酸型保健饮品。该方法操作简便、检测快速、结果准确。     

Molecular Properties of Post-Mortem Muscle. 7. Changes in Nonprotein Nitrogen and Free Amino Acids of Bovine Muscle

SUMMARY– Proteolysis and its relationship to tenderness were studied by measuring nonprotein nitrogen (NPN), free amino groups, and shear resistance during post-mortem aging of bovine muscle. Both NPN and free amino groups increased during post-mortem aging, indicating some degradation of proteins and/or peptides. However, neither the increase in NPN nor free amino groups was related to post-mortem tenderization since these quantities increased only after most of the improvement in tenderness had occurred. Much of the increase in NPN or free amino groups may originate from degradation of sarcoplasmic proteins or peptides. It is suggested that weakening or breaks at crucial points in the sarcomere, such as at the junction of the Z-line with the thin filaments, occur within the first 48-72 hr post-mortem and that this weakening or cleavage is responsible for tenderization. Cathepsin D may be responsible for this weakening but most of the available evidence is against proteolysis as the primary cause of post-mortem tenderization.     

香料烟中游离氨基酸含量随施肥量的变化

对依兹密尔香料烟3个部位烟叶中的游离氨基酸含量随施肥量的变化进行了研究,结果表明:(1)在同等施肥量条件下,成熟鲜烟叶中总游离氨基酸的含量随烟叶着生部位的升高而增加,但每一种氨基酸的表现又有所不同;(2)不同部位烟叶总游离氨基酸的含量与施肥量的关系规律表现不明显;(3)在施肥量较低(纯氮30～37.5kg/hm2)时各部位烟叶中苯丙氨酸、脯氨酸、天门冬氨酸和谷氨酸的含量总体表现较高,这有利于提高烟株的抗病性和烟叶质量。     

烘焙期间加料与未加料白肋烟游离氨基酸的变化

采用OPA、FMOC联合在线衍生反相高效液相色谱法测定了烘焙过程中加料和未加料的白肋烟游离氨基酸的变化。结果表明:①烘焙过程中未加料白肋烟的游离氨基酸总量呈先增后减的趋势,烘焙18min后游离氨基酸总量降低19%,其中降幅20%以上的有Asn、Asp、Arg;②加料白肋烟的游离氨基酸总量呈逐渐减少的趋势,烘焙18min后其游离氨基酸总量降低37%,其中降低50%以上的有Glu、Phe,降低40%以上的有Asn、Val;降低30%以上的有Asp、Ser、Arg、Lys、Pro;③未加料和加料的白肋烟中游离氨基酸的变化均主要发生在140℃。     

Changes in Muscadine Grape Juice Quality During Cold Stabilization and Storage of Bottled Juice

Muscadine grapes (Vitis rotundifolia, Michx.) of two cultivars (Noble and Carlos) were washed and extracted. The resulting juice was cold stabilized for 0, 7 and 60 days at 2°C, then treated, bottled, pasteurized and stored at 2°C and 24°C for 0, 4, 8, and 12 months. Carlos juice was lower in phenols and pH and higher in acidity than Noble. The high total anthocyanins and phenols in the Noble juice caused a significant loss in pigment during cold stabilization. Dilution of juice with 40% water and adjustment of the sugars was beneficial to flavor and color of Carlos, yet 40% dilution was too high for Noble juice. Treatment of either juice with CaCO₃ increased pH and decreased acidity. During 12 months storage, the Carlos juice became darker due to browning, while the Noble juice became lighter by losing pigment, especially at 24°C.     

Changes in the Polyunsaturated Fatty Acid Content of Potato Tubers During Growth, Maturation and Storage

SUMMARY— Kennebec and Red Pontiac potatoes were analyzed for fatty acids at intervals during growth and maturation of the tubers and subsequent storage at 4°C. During storage linoleic and linolenic were almost the only polyunsaturated acids present, but during growth and maturation considerable amounts of unidentified polyunsaturated acids were found. The percentage of polyunsaturated acids in the dry weight of tuber decreased to a low value near harvest time and remained near this value throughout the 6.3-month storage period, except that the value in Pontiacs stored 19 days was somewhat high. The percent of polyunsaturates in the total fatty acid fraction also dropped to a low value during growth and maturation but increased somewhat during storage. For this reason it may be better, when practicable, to make dehydrated products from freshly-harvested rather than from stored potatoes.
Potato dice contained as much polyunsaturated acid as the tubers they were made from; potato flakes contained somewhat less. In both products the degree of unsaturation of the fatty acid fraction was the same as for the tubers. NO off-flavors were noticed when samples were reconstituted. Apparently little or no oxidation took place during the processing.     

Sugar and Nonvolatile Acid Composition of Persimmons During Maturation

Sugars and nonvolatile acids of Japanese persimmons were identified and quantitated by GLC as oxime-TMS derivatives. Sugars quantitated were arabinose, galactose, glucose, fructose and sucrose. Fructose, glucose and sucrose were predominant and present in all cultivars from mature green to fully ripe. Quantities of all sugars varied significantly by cultivar and maturity. Nonvolatile acids quantitated were succinic, malic, citric, and quinic. Malic was the predominant acid in all cultivars followed by citric. Quantities of malic increased with maturity; citric decreased. Sorbitol and inositol were present in minor quantities and varied significantly by cultivar and maturity stage.     

Changes in Antioxidant Activity of Cyphomandra betacea (Cav.) Sendtn. Fruits During Maturation and Senescence

Antioxidants are extremely important substances that possess the ability to protect the body from damage caused by free radical induced oxidative stress. Antioxidants are derived from dietary sources, such as fruits, vegetables, and beverages. In this study, the antioxidant activity of different maturity stages of two varieties of Cyphomandra betacea fruits of Darjeeling was evaluated in vitro. The radical scavenging properties on 2,2-diphenyl-1-picrylhydrazyl, superoxide anion, hydroxyl radical, lipid peroxidation, nitric oxide, and reducing power as well as the flavonoids, phenolics, lycopene, and total carotene contents of methanolic extracts of the fruits were determined. All fruit extracts, mainly the mature red fruit of purple-red variety exhibited strong scavenging activity towards all radicals tested due to the presence of relatively high total phenol, flavonoids, and lycopene as well as total carotene contents. The findings suggest that purple red variety of C. betacea fruit is endowed with antioxidant phytochemicals, which could provide protection against oxidative stress induced diseases.     

酵母抽提物中游离氨基酸的测定与分析

本文首先摸索了游离氨基酸的HPLC法测定条件,建立了同时测定16种游离氨基酸的方法,然后对酵母抽提物中的游离氨基酸进行了分析研究。通过高效液相色谱法测定了热反应前后酵母抽提物、HVP粉、猪肉酶解物中的游离酸,得出结论：酵母抽提物中游离氨基酸的种类和含量最多;热反应后的酵母抽提物中氨基酸含量减少,且随着加入还原糖（木糖）含量的增多,游离氨基酸含量也随着减少。因此,酵母抽提物可作为Maillard反应制备肉味香精的良好氨基酸原料。     

Properties of Free Radicals in Protein and Amino Acid Pyrolysates

The ESR intensities (g=2.0042 ～ 2.0053) of free radicals in L-lysine and casein pyrolysates increased with increase of the heating time. In L-lysine pyrolysate (200°C, 20 min), the fraction insoluble in organic solvents and water accounted for 48.1% of the ESR intensity of the whole pyrolysate; the component responsible appeared to be a product of condensation polymerization, but the elemental analysis data indicated a smaller value for nitrogen than that expected for polylysine. The pyrolysis of casein brought about denatured products insoluble in water. The free radicals formed were stable for a week in distilled water and were unaffected by digestion with pepsin or pancreatin (37°C for 3 hr).     

Exocrine Pancreatic Secretions in Young Pigs Fed Diets Containing Faba Beans (Vicia faba) and Peas (Pisum sativum): Concentrations and Flows of Total,Protein-Bound and Free Amino Acids

Two experiments were carried out to investigate the effects of feeding diets containing faba beans and peas on the concentration, flow and composition of total, protein-bound and free amino acids (AA) in pancreatic juice collected from young pigs fitted with a pancreatic pouch re-entrant cannula. In Experiment 1, eight barrows, with an average initial weight of 8·5 kg, were fed one of two semi-purified diets formulated to contain 200 g kg⁻¹ crude protein (CP) according to a completely randomised design. In one of the diets, soya bean meal was the sole protein source; in the other diet, soya bean meal and faba beans (cv Fibro; dark-flowering) each supplied 50% of the dietary CP. In Experiment 2, five barrows, with an average initial weight of 18·1 kg, were fed one of two diets formulated to contain 150 g kg⁻¹ CP with peas (cv Ascona or cv Radley) as the sole protein source. There was no effect (P>0·05) of the diet, 8 h sampling period or experimental period on the concentration (mM), composition (% and g 16 g N⁻¹) and flow (mmol 24 h⁻¹) of total, protein-bound and free AA or on the percentage of protein-bound AA in pancreatic juice. The concentrations of total, protein-bound and free AA were higher in pancreatic juice collected from younger pigs in Experiment 1 than in pancreatic juice collected from older pigs in Experiment 2. However, the daily flows of total, protein-bound and free AA in pancreatic juice were similar in both experiments. The percentages of protein-bound AA in pancreatic juice were similar in both experiments. In conclusion, the concentrations, compositions and flows of total, protein-bound and free AA in pancreatic juice were not affected by diet, 8 h sampling period or experimental period.     

分光光度法测定调味品中氨基酸态氮的研究

采用分光光度计测定调味品中的氨基酸态氮,对影响测定结果的因素进行分析,并与甲醛滴定方法进行了比较.检出限为2μg,相对标准偏差为2.8%～5.8%,加标回收率为94.5%～100.9%.     

Influence of pH on Available Amino Acid Concentrations in Fermented Cornheal

Cornmeal was fermented at 45°C for 1, 2, 3, and 4 days. Meal was also allowed to ferment without a pH adjustment at 45°C for 1, 2, 3, and 4 days. The fermentation without a pH adjustment produced the largest concentrations of lysine, methionine, and tryptophan. Of the pH ranges tested, lysine was best produced at pH 5.0-5.5, methionine at 4.0-4.5, and tryptophan at 4.0-4.5. All samples fermented at pH 4.M.5 or at pH 5.0-5.5 for 1 and 2 days were significantly (P<0.05) higher in lysine, methionine, and tryptophan than nonfermented corn. Fermentations of 1 and 2 days produced the highest concentrations of available amino acids, which then decreased by days 3 and 4. Authors Nanson and Fields are with the Dept. of Food Science & Nutrition, College of Agriculture, Univ. of Missouri-Columbia, Columbia, MO 652 11.     

Changes in Fatty Acid Composition of Papaya Lipids (Carica papaya) During Ripening

Lipids from papayas (Carica papaya L.) Solo cultivar at various stages of ripeness were extracted and fractionated into neutral lipids (NL), glycolipids (GL), and phospholipids (FL). The major fatty acids of the three lipid classes at all levels of ripeness were C16:0, C18:1, C18:2, C18:3. NL increased in unsaturation with maturity as indicated in the decrease of the various saturated/unsaturated fatty acid ratios, GL decreased in the ratio of C16:0/C16:1 due to an increase in C16:1 fatty acid with increasing fruit maturity. The remaining fatty acids in GL remained relatively unchanged. The phospholipid fraction increased in unsaturation with maturity due to increases in C16:1 and C18:3 fatty acids.