Mineral composition of raw longissimus muscle derived from beef carcasses produced and graded in Venezuela

A total of 145 beef carcasses derived from cattle produced under tropical conditions in different regions of Venezuela were graded by the current grading system. Rib (longissimus) samples were excised, trimmed to zero fat cover and subjected to spectrophotometric analyses to examine the variation in ash, macro- and micro-mineral contents, according to the beef carcass grade. The analysis of variance indicated that the Venezuelan carcass grade did not affect significantly the ash or individual mineral content of the raw longissimus muscle; only the Na content tended to decrease (P < 0.10) as the beef carcass quality decreased from grade AA to grade C. Overall means +/- standard deviations are given for ash percentage (1.06 +/- 0.16) and content (mg/100g) of Ca (2.77 +/- 1.57), Mg (21.62 +/- 3.11), P (211.4 +/- 35.88), Na (76.06 +/- 30.88), K (243.81 +/- 63.93), Fe (1.93 +/- 0.58), Zn (4.13 +/- 0.82), Cu (0.084 +/- 0.041) and Mn (0.026 +/- 0.016). It was concluded that the variation in mineral composition of beef longissimus observed for this sample of tropical beef cattle, cannot be attributed to the Venezuelan carcass grade.     

Interfamily variation in comb wax hydrocarbons produced by honey bees

The hydrocarbons of honeybee comb wax vary significantly between colonies. This variation is explained in part by genetic (familial) differences among colonies. Even though significant differences in wax hydrocarbons exist among families, there is a high level of consistency within and among families in a correlation analysis, indicating structural constancy in comb wax. The significance of these results in interpreting the potential role of comb wax in the nestmate recognition system of the honeybee is discussed.     

3,5-二甲苯酚比色法测定市售蜂蜜中果胶的含量

建立了以3,5-二甲苯酚为显色剂测定市售蜂蜜中果胶含量的方法。研究表明,其最大吸收波长为450 nm,浓硫酸含量为70%左右,显色时间为20 min,NaCl用量为0.3 mL,且显色剂用量为0.3 mL。用于测定市售蜂蜜中果胶含量的相对标准偏差为1.44%,较适合进行蜂蜜中果胶含量的分析。     

Proximal analysis, fatty acids profile, essential amino acids and mineral content in 12 species of fishes of commercial importance in Venezuela

Proximate composition, fatty acid profile, essential aminoacid and minerals were determined in twelve fish species (armadillo, bocachico, cachama, carpeta, corvina, lisa, mero, merluza, pargo, robalo, tilapia and trucha). Proximate analysis: moisture, protein and ash, were performed using AOAC methodology, fat by Bligh and Dyer method, fatty acids by Gas Chromatography, aminoacid using High Performance Liquid Chromatography and minerals by spectrophotometric method. Results showed that moisture varies between 70.49% for Armadillo and 78.64% for Mero, protein between 18.70% for Merluza and 25.53 for Armadillo, ash between 0.94% for Mero and 2.13% for Carpeta and fat between 1.12% for Pargo and 6.15% for Cachama. Unsaturated fatty acids (omega 3) were the most common found for all the spices. Essential amino acids studied were present in all the spices. Tilapia (10.938 g/100 g of fish), Bocachico (9.231 g/100 g of fish) and Mero (8.738 g/100 g of fish) shown greater content of essential amino acids. Phosphorous was the most concentrated mineral with a mean value of 238.13 mg/100 g of fish followed by calcium with 42.11 mg/100 g of fish. It was concluded that all studied species are an excellent source of protein, omega 3 fatty acids and minerals.     

Mineral nutrient content in cow milk and dairy products in Argentina

Cow milk and dairy products supply essential inorganic elements for humans, and constitute the most important source of bioavailable calcium in our diet. In order to obtain data about mineral nutrient composition of dairy products that are produced and sold in Argentina, the contents of Ca, P, Mg, Na, K, Fe, Zn and Cu in whole and low fat fluid milk, dried milk and yogurt were analyzed. P was assessed by a colorimetric method, and the other elements by atomic absorption spectroscopy. In raw milk, the mineral content shows a certain degree of variability, in addition to the variability introduced by the different processing conditions, in order to meet the requirements prescribed by trade regulations and to produce dairy products. In all cases, skimming increases the concentration of mineral nutrients, which is especially remarkable in Ca contained in skimmed milk powder. In yogurt, added milk solids like dried milk or evaporated milk appreciably increase the mineral content, even more so if ultrafiltrates are used. These ultrafiltrates increase the Ca/P ratio, which probably improves Ca bioavailability. The results obtained in these analyses provide data that are not yet available from the National Table of Food Composition, and which prove necessary and fundamental for nutritional and dietary evaluation.     

电石法生产的PVC树脂中汞含量的测定

采用氢化物原子荧光光谱法测定了电石法生产PVC树脂中汞的含量,该方法回收率高,精密度好。在不同的加标水平下,其回收率为90.54%~96.88%,相应的RSD值均小于6%。该方法完全适用于电石法生产PVC树脂中汞残留量的测定。     

离子膜烧碱生产中氯中含水量的分析

介绍了利用浓硫酸的吸水性控制取样条件的一种方法,该法可以保证准确分析氯中所含的微量水,同时降低氯气对输送管道的腐蚀。     

膜式法生产固体烧碱含镍分析方法

介绍了膜式法生产固体烧碱含镍的分析方法 ,该方法操作简单、快捷 ,摩尔吸光系数为 1.72× 10 4 ,在显色反应属于低灵敏度反应 ,但该方法色泽结果对比明显。     

Microbiological quality of vanilla ice cream manufactured in Caracas, Venezuela

A total of 122 samples of vanilla ice cream, the base product used for all flavors, prepared by eight different large firms at the Metropolitan Area of Caracas, Venezuela, were analyzed for aerobic mesophilic and psicrophilic bacteria, Staphylococcus aureus, Enterobacteriaceae, and Filamentous fungi. Findings revealed that within the sampling, 56.6% complied with the international standards proposed for aerobic mesophilic bacteria, 68% for Staphylococcus aureus, and 23% for Enterobacteriaceae. Three serotypes of enteropathogenic Escherichia coli, one of Salmonella, and one of Shigella were found. Ten genera of Filamentous fungi were isolated and identified.     

Chemical composition and mineral content of legumes and cereals produced in Northwestern Argentina

Different varieties of bean (Phaseolus vulgaris), corn (Zea mayz), lentil (Lens sp), soya (Glycine max) and wheat (Tricticum sp) were analyzed in order to obtaining data of chemical composition and content of minerals to contribute to the International Food Data System INFOODS in the elaboration of Regional Food Composition Tables and to evaluate the quality of grains. The selected varieties were the ones produced in the northwestern region of Argentina. The beans were divided in five groups, according to their statistical similarity. The pallares variety is the one that presents bigger content of Cu (2.42 mg/100 g), Fe (76.03 mg/100 g) and Zn (6.08 mg/100 g). The samples of corn were divided in three groups, according to their statistical similarity. The leales yellow corn has bigger content of Zn (3.16 mg/100 g) that the other varieties of the region. The 8 rayas white corn is the one that presents bigger content of Fe (11.48 mg/100 g), while the pisingallo yellow corn is that of bigger content of Cu (1.21 mg/100 g).     

Trans fatty acid composition and tocopherol content in vegetable oils produced in Mexico

The purpose of this study was to evaluate the trans fatty acid (TFA) composition and the tocopherol content in vegetable oils produced in Mexico. Sample oils were obtained from 18 different oil refining factories, which represent 72% of the total refineries in Mexico. Fatty acids and TFA isomers were determined by gas chromatography using a 100-m fused-silica capillary column (SP-2560). Tocopherol content was quantified by normal-phase high-performance liquid chromatography using an ultraviolet detector and a LiChrosorb Si60 column (25 cm). Results showed that 83% of the samples corresponded to soybean oil. Seventy-two percent of the oils analyzed showed TFA content higher than 1%. Upon comparing the tocopherol contents in some crude oils to their corresponding deodorized samples, a loss of 40–56% was found. The processing conditions should be carefully evaluated in order to reduce the loss of tocopherols and the formation of TFA during refining.     

From acacia honey monosaccharide content to a new external binary plasticizer applicable in aqueous whey protein films

Plasticizer is an essential adjuvant in food and pharmaceutical film coatings affecting the appearance, mechanical and permeation properties of the final coat. In the present study, film formation and plasticization of native whey proteins (potential future “green” coating agents for pharmaceuticals and food products), were studied with free isolated films. Special attention was paid to the effects of plasticizer, preheating and film forming solution pH on the mechanical stress–strain and moisture permeation properties of whey protein films. Glycerol, binary mixtures of fructose and glucose, and non-crystalline acacia honey were studied as external plasticizers. The type and amount of plasticizer affected the mechanical stress–strain properties of the whey protein films. A short preheating treatment of whey proteins prior to film casting resulted in mechanically strong films with a reduced elongation. The film forming properties of aqueous whey proteins could be modified by adjusting the pH above the isoelectric point of β-lactoglobulin prior to film coating. For effective plasticization, whey protein films required a high amount of monosaccharide containing plasticizer ranging from 80% to 120% (calculated from the protein weight). A new external binary plasticizer having the same ratio of monosaccharides as non-crystalline acacia honey (fructose and glucose 1.67:1) was found to be applicable in aqueous whey protein films.     

微生物成矿原理及其在矿物加工过程中的利用

碳酸盐的成岩成矿作用主要与微生物作用有关,硫杆菌属在硫化矿中的氧化作用为自身构成提供物质基础和能量,海底锰结核的成因表明超微生物搭建了锰结核的构架。介绍了微生物在浮选和浸出技术中的应用和在这些技术应用中的机理。     

Plasma amino acids profile of healthy pregnant adolescents in Maracaibo, Venezuela

One hundred female adolescents (13-18 y) were clinical and anthropometrically studied to select only those with adequate nutrition. Most adolescents belonged to IV socio-economic stratum families (worker class). Height, weight, age, body mass index and medial arm circumference were used as anthropometric parameters. After screening, only 41 non pregnant girls (control) and 42 pregnant girls with adequate nutrition were selected to analyze plasma amino acids. Fasting peripheral venous blood was drawn, and plasma amino acids were analyzed by HPLC. Amino acid concentrations were expressed as umol/L +/- SE. SAS/STAT program was used for statistical analysis. Amino acid values of control adolescent group were found in ranges reported by other investigators, with slight variations, mostly in diminution, presumably due to nutritional, metabolic or genetic conditions of people living in tropical regions. In pregnant healthy adolescents, distributed according to gestational age: < 32 weeks (n = 30) and > 32 weeks (n = 12), a diminution of total molar plasma amino acids was found, by comparing with control values. Ten amino acids (Pro, Gly, Gln, Arg, Ser, Orn, Tau, Leu, Thr and Val) appeared significantively diminished throughout gestation, being Gly. Gln and Arg most affected since earlier weeks. During the 2nd period. Thr and Val increased their grade of affectation; whereas some amino acids values (Orn, Pro and Tau) tended to recuperate. Several of affected amino acids are gluconegoenic, thus, they could be utilized to supply the energy required by the pregnant adolescent against her double stress: the fetus development and her own development. The plasma amino acid values reported in both, healthy non pregnant and pregnant adolescents, could be taken as regional referential profile of plasma amino acids in this poblational group for further research on adolescent and fetal--maternal malnutrition.     

浓硫酸中羟基乙酸的游离态含量及其总含量的测定

针对水溶液电位滴定法无法将硫酸与羟基乙酸的滴定曲线突跃点分开,无法测定浓硫酸中羟基乙酸的问题,采用非水溶液电位滴定法,使用丙酮作为溶剂,对含有浓硫酸的羟基乙酸样品中的游离态羟基乙酸及其总含量进行了测定。以丙酮为溶剂,可以很好地将2种酸的滴定曲线突跃点区分开来,并能对游离的羟基乙酸做定量分析。此外,羟基乙酸自身容易失水生成二乙交酯和多交酯,通过碱水解,再采用上述方法,可以测定出羟基乙酸盐的含量,即得到羟基乙酸的总含量。试验表明:该方法准确性高、重现性较好、操作简便;但无法有效区分羟基乙酸和其他有机强酸。     

降低氯醇法环氧丙烷中总醛含量的措施

介绍山东滨化东瑞化工有限责任公司环氧丙烷生产情况,改进皂化系统、脱轻系统部分工艺指标后,环氧丙烷中总醛质量分数由0．005％降至0．0015％,满足用户要求。     

The adaptation and validation of the food security scale in a community of Caracas, Venezuela

This paper describes the process of modifying and validating a hunger index developed in the United States by Wehler et al (1992). It is part of a research whose main objective is to develop and validate a simple method that measures both quantitative (food sufficiency) and qualitative (female self-perception) dimensions of household food insecurity. In a pilot study, the original instrument was modified from a 2 point 8 item to a 4 point 12 item scale. Precision measured with Alpha Chronbach's coefficient was high (0.871) suggesting consistency in the scale's items. The instrument was applied to a sample of 238 poor and very poor households in a peri-urban barrio of Caracas. To determine overall internal validity of the scale the relationship between possible economic, social and behavioral determinants and food security level measured with the scale, was analyzed. Construct validity of the scale was established with factor and principal components analysis. Finally, with multiple regression analysis evidence is presented for overall validity of the scale. Four determinants: predictors of food sufficiency score, monthly income per capita, social class, and number of children in the household predict in the expected direction self-perceived food security level (R2 = 0.343). Results suggest that this instrument, together with an abbreviated measure of food sufficiency, based on strategic foods may be a valid, precise, and simple method for identifying and monitoring households that suffer from some degree of food insecurity in poor urban communities.     

Nutritional status in preschoolers attending a public day-care center in Valencia, Venezuela

With the purpose of evaluating nutritional status in a group of preschoolers attending a public day care center in Valencia, Venezuela (2002), a research was made for social stratus, anthropometric variables; weight, height and arm circumference, hemoglobin, seric retinol, presence of parasitosis and food consumption, as well as the mother's educational level. The program SPSS 11.0 and the t Student, ANOVA Post Hoc from Bonferroni and Fisher (p < 0.05) were used. A predominance of the female sex was presented (52%). According to the social stratus, 23.3% was located in the middleclass, and 76.8% on some level of poverty. 60% of the middleclass mothers had finished their high school education, while only 9.8% of the mothers in poverty had reached that level. According to the Z values (H/A, W/H and AC/H), high percentages under -1.00 were observed (27.3%, 25.6% and 24.5%, respectively). The W/H and AC/H of children of mothers studying in a university presented discrepancies when compared with children of mothers with a primary educational level. A 25.9% of anemia was presented, and there were differences between anemic and non-anemic groups for H/A and AC/H. Protozoaries were observed in 61.0%, helmintos in 16.9% and both in 22.1%. There was a 2.6 times higher risk of presenting nutritional deficiency for AC/H in the group found with parasites. An adequate consumption of energy and iron was found, with an excessive consumption of proteins and vitamin A. It is concluded that there exists a nutritional risk evaluated through hematologic parameters, the presence of parasitosis and social stratus.     

Mechanical properties with respect to water content of gelatin films in glassy state

Changes on the structural and molecular level of gelatin films induced by hydration below 25±3% water content (glass–rubbery transition at ambient temperature) were identified with DSC and FTIR spectroscopy. Three main stages of hydration were distinguished: (I) water bound by high-energy sorption centres; (II) structural water; (III) polymolecular layer water. The mechanical behaviour of gelatin films at each stage of hydration was characterized. Relaxation of the films during hydration was taken into account in the analysis of results. Hydrated gelatin films were characterized as brittle below the glass–rubbery transition at ambient temperature, however some improvement of mechanical properties related to a higher renaturation level was showed between 7 and 14% of water content in stage II (structural water).     

蜂蜜的热裂解产物分析

为了研究卷烟添加剂蜂蜜的热裂解产物对卷烟烟气成分的影响,应用热裂解-气相色谱/质谱（Py-GC/MS）联用技术,模拟卷烟燃烧的环境,对蜂蜜在不同裂解温度（300℃、600℃、900℃）和不同氧气浓度（大气环境、10%O2）下的裂解产物进行成分分析。结果表明,在相同裂解氛围和不同裂解温度中,高温时蜂蜜的裂解产物种类多于低温时的;在相同裂解温度和不同裂解氛围中,蜂蜜裂解产物的质量分数不同;蜂蜜在各种不同裂解条件下的主要产物是糠醛、5-甲基糠醛及5-羟甲基糠醛等醛类物质,还产生多种酮类和呋喃类等物质;蜂蜜的大部分热裂解产物是构成卷烟烟气香味的重要成分。