Antioxidant Potential and Polyphenol Content of Selected Food

Phenolic compounds are natural antioxidants present in plant foods, which are important to human health. This study aimed to measure the total antioxidant potential with the FRAP (Ferric Reducing Antioxidant Power) method and the total polyphenol content of 44 common consumed foods; represented by vegetables, pulses, fruits, cereals and breads. The antioxidant potential ranged: in vegetables 0.033–3.209, in pulses 0.342–0.387, in fruits 0.312–2.833, and in cereals and breads 0.062–1.709 mmol/100 g in fresh mass, respectively. The antioxidant potential of the foods tested was related to the total polyphenol contents.     

Determination of protein in foods: comparison of net protein and crude protein (N × 6.25) values

The purpose of the present study was: (1) to determine net (true) protein (NP) values as sums of amino acid residues and to compare them with crude protein (PA) values; and (2) to calculate the nitrogen-to-NP conversion factors by means of linear regression analyses between the NP values and nitrogen content. The differences between NP and PA values varied between food groups. The NP values in milk and milk products were, on average, 5.5% smaller than the corresponding PA values. The corresponding figures for other foods were: meat and meat products 15.4%, fish and fish products 20.6%, cereals and bakery products 12.2%, vegetables, fruits and berries 13.9% and miscellaneous processed foods 16.1%. In the present study the nitrogen-to-NP conversion factor for milk and milk products was 5.94, meat and meat products 5.17, fish and fish products 4.94, cereals and bakery products 5.40, vegetables, fruits and berries 5.36 and miscellaneous processed foods 5.51; the general conversion factor for all foods was 5.33. The above respective factors were 5.0, 17.3,21.0, 13.6, 14.2, 11.8 and 14.7% smaller than the official factor of 6.25. We conclude that the traditional PA values (N × 6.25) deviate significantly from the NP values. We recommend that protein definitions and methods of determination should be re-evaluated in the appropriate international organizations and updated in line with current knowledge and analytical capabilities for both scientific and other purposes.     

Zinc levels in foods from southeastern Spain: relationship to daily dietary intake.

The zinc content of 300 food and 79 beverage samples was determined using flame atomic absorption spectrometry. Sample recoveries, repeatability, and analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of this technique. Mean zinc concentrations varied from 0.02 microg/ml in fresh water to 71.0 microg/g (fresh weight) in pork liver. The daily dietary intake of zinc for inhabitants of southeastern Spain was estimated to be 10.1 mg (5.5, 4.0, 0.5, and 0.1 mg Zn/day per person from foods of animal and vegetable origin, drinks, and other foods, respectively). Zinc levels found in high protein foods (meat, fish, milk products, eggs, dry fruits, cereals and legumes) were significantly higher than those found in food with a low protein content (vegetables, fruits and drinks) (p < 0.001). A significant linear correlation between zinc levels and the corresponding protein content of cereals, legumes and dry fruits was found (r = 0.754, p < 0.005). Zinc concentrations in milk samples were significantly modified by the thermal treatment (p < 0.001), and the skimming (p < 0.05) and calcium enrichment processes (p < 0.001). Shellfish zinc levels were also significantly higher than those measured in fish (p < 0.05). Mean zinc concentrations found in cheese were statistically higher than those determined in the remaining milk products (p < 0.001). Zinc levels measured in distilled beverages were also statistically lower than those found in fermented ones (p < 0.001).     

Presence of benzodiazepine-like molecules in food and their implication in the nutrition of cirrhotic patients

Benzodiazepine (BDZ)-like compounds, present in trace amounts in normal subjects increase in the blood of liver cirrhotic patients. The origin of these compounds is still unknown but they are present in medicinal plants and foods. Herein we report the detection of BDZ-like molecules in fruits, vegetables, cereals, meat, milk and cheeses and in different cultivars of potatoes, tomatoes and carrots. The extracted food was separated by HPLC purification and the collected fractions were tested by radioreceptor binding assay in order to evaluate their ability to selectively bind the central benzodiazepine receptors. The mean value was 14.80 ng of diazepam equivalent (DE)/g in fruits, 4.34 ng DE/g in vegetables, 6.35 in cereals and 4.09 in meat. BDZ-like compounds are poorly present in cheeses and completely absent in olive and seeds oil. From these findings it is possible to select food with low amount of BDZ-like molecules useful for cirrhotic diet in order to prevent hepatic encephalopathy.     

Water-Holding Capacity of Some African Vegetables, Fruits and Tubers Measured In Vitro

The acid detergent fiber (ADF) contents of some vegetables, starchy fruits and tubers, and their acetone dried powder (ADP), have been estimated to determine the water-holding capacity (WHC) of these foods when raw or cooked. Water-holding capacity was variable among the different classes of foods, being 2.1 - 4.5 g/g ADP from starchy fruits and tubers, and varying between 7.8 and 18.2 g/g ADP from leafy and nonleafy vegetables. Cooking solubilized the starch in starchy fruits and tubers resulting in an increase in relative proportion of ADF in the ADP with a significant (p < 0.05) increase in WHC. Vegetables were not markedly affected by cooking except for okra and waterleaf, the WHC of which was significantly (p < 0.05) increased on cooking.     

Food patterns during an economic crisis among pregnant women in Purworejo District, Central Java, Indonesia

A cross-sectional study was conducted between 1996 and 1998. Six 24-hour recalls were performed during the second trimester of pregnancy among 450 women in Purworejo District, Central Java, Indonesia. The objectives of the study were to assess the food intake and food pattern among pregnant women before and during the economic crisis. Before the crisis, rich women had the highest intakes of animal foods, fats and oils, and sugar. Food intake among the urban poor and the rural landless poor subgroups was influenced by the emerging economic crisis. Although the price of rice increased, the intake of rice also increased among all subgroups. Rural poor women with access to rice fields increased their intake of rice and decreased their intake of nonrice staple foods (p < .05). There were significant decreases in the consumption of chicken by rich women and rural poor women with access to rice fields (p < .05). Rice was a strongly inferior good and remained an important supplier of energy, protein, and carbohydrate. Nuts and pulses were important suppliers of calcium and iron, and vegetables were an important supplier of vitamin A. Rich women increased their intake of nuts and pulses, vegetables, fats and oils, and sugar when their intake of rice increased (p < .05). The food patterns were based on rice, nuts and pulses, and vegetables, i.e., plant food. All but the rich women decreased their intake of nutritious foods such as meat, chicken, and fruits. The intake of nuts and pulses and of vegetables increased, whereas the intake of cooking oil and sugar remained constant.     

The contribution of food groups to the nutrient intake and food pattern among pre-school children

A pre-school-based dietary survey, using 7-day records, was carried out in Sweden in the Stockholm area at 12 pre-schools; the survey included 109 of 131 participating children. The present study was designed to describe weekday and weekend food patterns, i.e. the frequency of consumption of food items and the contribution of energy and nutrient intake from different food groups, and to explore how foods are related in pre-school children's diet. At pre-school, all children except one ate vegetables and fruits about once a day, and all children consumed, on average, milk and cheese, meat products, bread and breakfast cereals and fats more than once a day. Milk and cheese products, bread and breakfast cereals and meat products were the primary source of energy and protein. The main source of dietary fibre was bread and breakfast cereals, potatoes and fruits. The “low-nutrient foods”, e.g. confectionery, buns, and soft drinks, contributed 20% of the energy during the weekdays and 33% during the weekend days. When all food groups (g/MJ) were analysed simultaneously in a Principal Components Analysis (PCA), 52% of the variation was explained. The food consumption data were described using four food clusters: milk and cheese products; bread and breakfast cereals; meat, potatoes and cooked cereals; confectionery, buns and soft drinks. In conclusion, the PCA seems to be a useful visual tool for elucidating how foods are related in the diet.     

Determination of Iron-Binding Phenolic Groups in Foods

A spectrophotometric assay was developed with the specific aim of determining the content in foods of iron-binding phenolic compounds. Foods were extracted with dimethylformamide (50%) and an ironcontaining reagent was added. The resulting color was due to formation of Fe-galloyl and Fe-catechol complexes. These complexes had different absorbance maxima and could thus be separately determined by readings at two wavelengths. The method was simple and had good precision, accuracy and analytical recovery. The new method was compared with two commonly used methods for determination of phenolic content in cereals, fruits, vegetables, spices and beverages.     

Dietary fibre and fibre-rich by-products of food processing: Characterisation,technological functionality and commercial applications: A review

Incidental products derived from the manufacturing or processing of plant based foods: cereals, fruits, vegetables, as well as algae, are sources of abundant dietary fibre. These fibre-rich by-products can fortify foods, increase their dietary fibre content and result in healthy products, low in calories, cholesterol and fat. They may also serve as functional ingredients to improve physical and structural properties of hydration, oil holding capacity, viscosity, texture, sensory characteristics, and shelf-life. Analytic methods and fractionation techniques of dietary fibres are evaluated.     

不同来源食用纤维性能的研究

农副产品如谷物、蔬菜、豆类、甜菜以及海藻类等加工过程产出的副产物是生产膳食纤维的丰富资源.这些富含纤维的副产物可以强化食品营养、增加食品纤维含量,因而得到热量低、低胆固醇和脂肪含量少的健康食品.膳食纤维也可以作为功能性成分改变产品如水合作用、持油能力、粘性、质地、感现性和货架期等物性和结构性能.     

Current Methods for Extraction and Concentration of Enteric Viruses from Fresh Fruit and Vegetables: Towards International Standards

Virus-contaminated soft fruits or vegetables are increasingly identified as causes of foodborne viral illness. Noroviruses and hepatitis A virus are the most common pathogens in viral infections transmitted by these kinds of foods. To improve microbiological detection and monitoring and to increase insights into the contribution of fruits and vegetables to foodborne viral transmission, sensitive, reliable, and standardized methods are needed. More studies on virus detection methods for foods are being published, but validated consensus protocols are not yet available. In this paper, different methodologies are reviewed critically. The use of process controls and internal amplification controls is discussed.     

湖北省部分居民1982-2002年食物消费变化趋势

目的描述湖北省城乡居民食物消费现状及变化趋势。方法在全省选取960户2942,＆进行膳食调查。膳食调查采用连续3d称重法和24h回顾询问法调查居民所有摄入食物。结果居民平均每标准人日粮谷类食物摄入量为354．2g,蔬菜为361．9g。水果为14．4g,畜禽肉类为67．6g,水产品类为53．2g,蛋类28．3g,奶类及其制品为n．3g,豆类及其制品为20．2g,食用油摄入量为51．8g,食盐为10．6g,酱油为9．4g。结论湖北省城乡居民膳食质量有所提高,其中动物性、奶类食物、水果、豆类及油脂类的摄入量均有所增加。但膳食中水果、奶类、豆类摄入量仍然很低。城乡居民膳食中谷类食物、蔬菜的消费量出现了下降趋势,但动物性食物和油脂摄入量明显上升,出现了失衡的现象。膳食结构趋向“高能量密度”,部分人群的膳食已经偏离了平衡膳食的要求。当前营养改善工作应从营养状况的双重负担的特点出发,同时解决营养不良和营养失衡的问题。     

一些果蔬对活性自由基和亚硝酸盐的消除作用

对29种新鲜水果和蔬菜的一般营养成分和过氧化物酶、过氧化氢酶活性以及对H_2O_2和NaNO_2的消除能力进行了测定。结果表明,在模拟胃液条件下,各种供试的新鲜果蔬对活性氧自由基和亚硝酸盐均具有不同程度的消除能力,其消除量与新鲜果蔬中的蛋白质含量呈极显著正相关。谷胱甘肽、还原型辅酶Ⅰ、维生素E、维生素C和半胱氨酸等还原性食品成分对NaNO_2和H_2O_2都有良好的线性消除关系。煮沸处理后,有机酸含量高的果蔬对NaNO_2和H_2O_2的消除能力增强,有机酸含量低时,其消除能力下降。提示果蔬对活性氧自由基和亚硝酸盐的消除能力取决于果蔬中还原性食品成分的种类、含量及其氧化还原特性。     

Model analysis of sorption isotherms

The equation developed by Blahovec and Yanniotis, which is based on surface adsorption and solution water, was applied for fitting experimental sorption data for starchy and high protein foods, fruits and vegetables, nuts, legumes, and seeds. Analysis of sorption isotherms shows that surface adsorption is more important than solution water in the isotherms for cereals, potatoes, legumes and seeds, while in vegetables, fruits, meat, milk products and some nuts solution water is more important. The ratio of solution water to surface adsorption increases as water activity increases, it is higher for the adsorption isotherm than the desorption isotherm at any water activity value and decreases as temperature increases.     

牛奶中泛酸含量测定

目的：对牛奶中泛酸的本底含量进行测定,为乳制品中泛酸的强化提供数据支持。方法：选取大量牛奶样本,通过微生物法和高效液相色谱法对泛酸含量进行测定。结果：牛奶中的泛酸含量大约为253～502μg/100mL,平均值为365.9μg/100mL。结论：乳制品中强化泛酸可以依据上述数值参考添加。     

Interactions between plant proteins/enzymes and other food components,and their effects on food quality

Plant proteins are the main sources of dietary protein for humans, especially for vegetarians. There are a variety of components with different properties coexisting in foodstuffs, so the interactions between these components are inevitable to occur, thereby affecting food quality. Among these interactions, the interplay between plant proteins/enzymes from fruits and vegetables, cereals, and legumes and other molecules plays an important role in food quality, which recently has gained a particular scientific interest. Such interactions not only affect the appearances of fruits and vegetables and the functionality of cereal products but also the nutritive properties of plant foods. Non-covalent forces, such as hydrogen bond, hydrophobic interaction, electrostatic interaction, and van der Waals forces, are mainly responsible for these interactions. Future outlook is highlighted with aim to suggest a research line to be followed in further studies.     

Determination of selenium content in selected Pakistani foods

Owing to increased concern in a number of diseases associated with low-selenium (Se) foods, the estimation of total Se content (TSC) is the focus of research these days. TSC was determined in fruits, vegetables, meat, milk, poultry, fish and cereals. Hydride generation atomic absorption spectrometric method was employed using the wet digestion method. Different certified reference materials were used for the validation of the method. The lowest Se content was found in plant-based foods, whereas the highest was in fish and appreciable in other animal-based foods. The data was compared with TSC data from other countries. TSC in Pakistani foods was comparable with other countries, with few exceptions. This report may serve as a database for TSC in Pakistani foods.     

MICROBIOLOGICAL CONSEQUENCES OF MINIMALLY PROCESSED FRUITS AND VEGETABLES

Microbiology is an important factor in the quality of minimally processed fruits and vegetables. Type of food, temperature, humidity, and use of modified atmosphere or low dose irradiation can influence the microecology of a food. Changes in the microbial ecology can likewise influence the ultimate safety and overall quality of fruits and vegetables. Therefore, food scientists must consider the microbiological consequences of all practices involved in production, processing, and delivery of these products.     

微孔板式微生物法测定婴幼儿配方乳粉中泛酸含量

目的：通过对国标微生物法的改进,采用微孔板的方法对婴幼儿配方乳粉中泛酸的含量进行测定研究。方法：采用国标微生物法的改进方法-微孔板法,将合适浓度的植物乳杆菌液接种至含有试样液与培养液的无菌微孔板中,培养一定时间后测定吸光度值,根据泛酸含量与吸光度值的标准曲线计算出试样中泛酸的含量。通过精密度实验、准确度实验、加标回收实验对此方法进行评价。 结果：实验室所采用微孔板式微生物法的标准曲线线性良好,相关系数r=0.9965,精密度实验的相对标准偏差RSD为1.90%-5.32,准确度实验结果表明质控样品的泛酸含量各平行检测值均在定量值范围内,且平均值为6.91mg/100g,测定值结果间RSD为1.08%,回收率为89.7%-108.2%,说明方法精密度较高,对样品检测结果准确性较高,方法的系统误差小。结论: 采用的国标物法改进的微孔板式微生物法操作简便、结果准确、能够降低工作量,提高工作效率,能够应用于实验室对婴幼儿配方乳粉中泛酸含量的测定。