Vol. 10 No. 5 (2012)

Human milk is considered as the best form of nutrition for the first few months of human life. The part that contributes to the important function of human milk contains oligosaccharides which are not found in infant formulas. Human milk oligosaccharides (HMOs) are the third most abundant molecular species in human milk after lactose and fat and its amount approximates15 g/L. To date, about 200HMOs have been purified and theirstructures have been determined. Basic core structure of HMOs is lactose at the reducing end elongated by fucose, N-acetylglucosamine and sialic acid. HMOs are considered to be one of the most important growth factors for intestinal bifidobacteria, beneficial bacteria dominated in gastrointestinal tract of breast-fed infants, andpotential inhibitors of adhesion of pathogenic bacteria to epithelial surfaces. For this reason, there is a continuous interest in finding structures as well as synthesis of HMOs by enzymatic method that can be applied for infant foods and drugs. This review focuses on structure and functions of HMOs, and enzymatic synthesis of some well known HMOs.

Toadis consideredas a fooditem with highnutritionalvalue. It has been used to improve thenutritional statusof children.Toad meat is highly nutritious:53.36 % protein, 12.66% lipid, 540 mg/100g calcium, and 850mg/kg zinc... The resultsin this study showed thatdryingof freshtoadat 100oC for 7h gave the best sensory quality. A formulasupplemented with3%toad dried powder wasthe bestchoice for productionof child nutritional powder. This formula complied theneed of children from 6 - 24 monthsof age with 40.58% protein, 72.02% calcium, 30.8%zinc.The final nutritional powder stored for 3 months still satisfies the microbiological and nutritional criteria issued by the Vietnam Ministry ofHealth.

At present, fruit juiceproductionis interested by many companies in Vietnam, and also preferedby consumers due to its high nutritional values and bioactive compounds which are beneficial for health. In this paper we study the processing of beverage from Nam Roi pomelo and aloe, two materials possessing lots of appealing properties for human healthand arecheap and available. Treatment regimes to remove the bitter taste of pomelo and retainthe crunchy structure of aloe gel includeblanching in hot water, at 90oC for 5 min, then immersing in 1.5% CaCl2for 60 minutes. Suitable treatment for pomelo was blanching in 1% NaOH at 75oC for 30s. Optimal conditions for activity of enzyme pectinex Ultra-SPL to increase the yield of pomelo juice were enzyme concentration of 0.03%, temperature of 40°C for 60 min. The ratio of aloe/ pomelo juice was 1/20. The results of this research open up the possibility for the production of functional drinks from pomelo and aloe.

The instant mulberry powder was produced by spray drying from condensed liquid extraction of mulberry leaves (supplemented with some additives). In this experiment, we have used the drying spray method (dryer spray MOBILE MINOR - Denmark) to produce instant powder from mulberry leaves grown in Viet Nam. Based on research and survey of technology parameters affect the drying and the rate of blending of additives suitable for the purpose of producing instant powders that DNJ content ≥ 1%, with taste, attractive colors, easy to use, we have identified technological processes producing instant powder of mulberry leaves with the specifications as follows: Using extraction solutions with total sub solid 200Bx the input temperature is 1300C, the input flow pump is 1500ml / h, the efficiency of product reached 60% (Wsp <5% ). To create tasting of product, condensed solution of dry mulberry leaves should be added a number of additives such as 0.6% sweet grass; 6% strawberry flavor.

Vermicelli is the traditional dish of Vietnam which is the main material to prepare “Hue Beef rice vermicelli” (Bun bo Hue), a very famous specialty originated from Huecity, the former imperial capital of Vietnam. Flavor and taste are important attributes of vermicelli. This study was carried out to determine the change in 2-AP and other volatile compounds as influenced by different durations of soaking rice in water during vermicelli processing. In order to identify and quantify the amount of 2-AP and other volatile compounds 2-AP extracted from pandan leaves was used as standard. Results indicated that 2-AP and other volatile compounds clearly changed in the vermicelli processing process and soaking for 12 hours was recommended.

The extraction and purification of anthocyanin pigments from calyx of Hibiscus sabdariffa, and its use as potential rapid indicator paper for detecting the borax in food were investigated. By using the colour comparison and the differential pH methods, the optimal conditions for pigment extraction were identified as follows: ethanol solvent to water is 50:50 with supplement 1% HCl; the ratio of solvent per raw-material is 14 ml/1g; extracting duration is 6 days. By fractional extraction method, the crude anthocyanin pigments are isolated from extracts of Hibiscus calyx. The concentration of pigments in the dry and fresh material was 15.2% and 1.06%, respectively. The acidity of the dry ingredients is 3.37 mldH+ /1g of raw material, the acidity of the dry pigment is 3.83 mldH+/1g of colour substance, respectively 0.58 mldH+ /1g dry material and the acid reduced 83%. By surveying several conditions for production of the indicator paper, the appropriate parameters are selected with color dilution of 1gram of dry colour substance to 400ml distilled water ratio; duration of color impregnated on paper is 120 seconds; the duration of indicator paper exposure to food (or food fluid) is 90 seconds. A minimum level of the indicator paper for detecting the borax is identified as 40 mg/1 kg of food. This result has shown that the minimum detectable limit is equivalent to turmeric paper. As for sensitivity, when testing on a number of food materials, the similar results were also been obtained.

So far fragrance of rice has mainly been determined by the traditional sensory method. This evaluation is fast but does not define precisely because it depends entirely on subjective assessment of the evaluator’s olfaction. To overcome this shortcoming, the modern physico-chemical methods, SDE-GCFID and SDE-GCMS were employed. In these analytical processes, quantitative analysis of 2-AP content in pandan’s leaf was performed to serve as basis for comparison with that in aromatic rice. By these methods, since 2005, 2-AP and some other aromatic compounds in aromatic rice have been identified and quantified in thePhysicochemicalLaboratory, Centerfor Biological and Chemical analysis and experiment,University of Agriculture andForestryHo Chi Minh City. In this laboratory from 2010,the content of2-APin theold, matureand young leaves of Pandanus were accurately quantified andused asa standardforquantification of2-AP infragrant rice usingSDE(orSPME)extraction methodcombinedwithGC-FID and GC-MS. The limit of detection(LOD) andlimit of quantification(LOQ) ofthemethod were also determined.

Pentosans are polysaccharides which exhibit both dietary fibre and prebiotic properties. Consumption of pentosan prevents the growth of colon cancer, promotes absorption of minerals and enhances immune system. In this study, the grain of 10 rice, 10 maize and 13 sorghum cultivars were selected to analyse pentosan concentration. The results showed that total and water-soluble pentosan content varied among these cereals, among these maize grains contain highest concentration. Wide variation in petosan concentration was also found within each grain group. Total and water-soluble pentosan content ranged from 0.54 to 1.65% and 0.01 to 0.02%, for rice cultivars; 0.54 to 2.33% and 0.01 to 0.03%, for sorghum cultivars; 2.81 to 4.1% and 002 to 0.1%, for maize cultivars, respectively.

A study was caried out to examine the effect of post-harvest treatment with 1-methylcyclopropene on avocado fruits in storage. The avocado fruits(Persea americana Mill.) at 20 weeks after flowering were harvested from orchard in Kam Leo, Thang Hoa, Daklak province in year 2011. The quality of avocado fruits was identified in terms of the firmness at 35.50 kg/cm2. Total sugar content of 7.20%, total acid content of 0.05%, vitamin C content of 68 mg%. The avocado samples were exposed with 1-MCP at the concentrations: 300ppm, 400ppm, 500ppm, 600ppm, 700ppm during the time of 12, 15, 18, 21, 24 hours, then kept at ambient temperature ( 25 to 300C; RH of 85 to 90%). Research results of single factors show that the quality of avocado fruits exposured with 1-MCP at the concentration of 500ppm during 12 hours is the best, which has weight losses lower than 10% compared with other samples after 12-day storage. Research results of multi-factor show that weight loss is lowest after 12 day storage when the concentration of 1-MCP for preserving avocado is 500 ppm and the time of 1-MCP treatment is 13hours30mins.

Starter culture is a source of pure microorganisms that are used for controlled fermentationto produce traditional fermented products with high quality, stability, and safety. The starter culture derived from mold contains spores and hydrolytic enzymes. This study was conducted to determine the optimal culture conditions for spore formation and the protease biosynthesis of mold Mucor elegans, to set up a manufacturing protocol for the starter culture that can be applied for producing the fermented soybean product “Chao”. It was identified that the medium with soybean meal and rice flour in a 50/50 ratio was the best for start culture production.

In milk, lipids occur in the form of globules with diameters varying from 0.1 to 15 μm. These fat globules have a surrounding thin film which is called the milk fat globule membrane (MFGM). Fat in the core of the globules is mainly composed of neutral triacylglycerides while the lipid moiety of the MFGM fraction mainly consists of polar lipids. The protein moiety of the MFGM also has a specific composition with mainly glycosylated proteins, which are greatly different from those in milk plasma. Milk contains as little as 2 g/L of MFGM material. However, this material received much attention in recent years due to both its health-beneficial properties and technological functionalities. This paper compiles up-to-date knowledge concerning the health-beneficial effects from consumption of MFGM components. In addition, basic knowledge about composition and structure of MFGM is also briefly discussed.

Predictive mycology aims at predicting fungal development in foods and raw products. For many years, most of the studies concerned food pathogenic bacteria. Recently, there is a growing concern about food contamination by moulds, especially strains responsible for mycotoxins production. This paper advocates the use of specific models for describing germination and growth of mould.

The objective of this study was to determine the effiect of 1-MCP, an inhibitor of cell ethylene receptor, at various concentrations on preseved litchi fruits (Litchi sinensis Sonn.. cv. Thieu). The fruits were harvested from the local orchards in Bac Giang and transported to laboratory within 3 hours. Maturity-uniform litchi fruits without any defects were selected and treated with 1-MCP at the concentrations of 0.300 and 600 ppb for 12 hours. Following treatment, litchi fruits were kept at 4°C for storage. The results indicated that 1-MCP has positive effect on maintaining the quality of litchi fruits cv. Thieu. The most effective treatment to preserve the litchi quality after storage was 600 ppb 1-MCP for 12 hours. This concentration reduced weight loss and delayed changes of skin color and browning, minimised the loss of TSS, sugar and vitamin C content within 1 month storage.

Changes in chemical composition (vitamin C, polyphenol) and antioxidant activity of guava fruits collected in Dong Du, Gia Lam, Hano at different maturity stages were examined. The maturity stages were mature green, color turning, ripe and overripe. The results showed that vitamin C content sharply increased during ripening and reached the maximum value at ripe stage. Both polyphenol content and antioxidant activity decreased during ripening. Changes in polyphenol content was significantly correlated with changes in antioxidant activity.

This study provides information on the fatty acid composition and trans fatty acid content analyzed by gas chromatography of selected Vietnamese instant noodle products and accompanying additive oil bag.. Five most abundant fatty acids were C14:0, C16:0, C18:0, C18:1 (9c) and C18:2 (9c, 12c). The concentration of saturated fatty acids ranged from 34% to 45% and from 51% to 60%, and of polyunsaturated fatty acids ranged from 12% to 20% and from 6.7% to 11% in additive oil bags and noodles, respectively. Trans fatty acids were detected in all samples but at low concentration and the content ranged from 0.16% to 0.83% of total methyl ester fatty acid in noodles and from 0.23% to 0.7% of total methyl ester fatty acid in small additive oil bags. Trans 18:2 isomers were the major group of trans fatty acids which were found in all the analyzed brands, representing about 80% of total trans isomers.