Journal of Food Biosciences and Technology
Year:2015 | Volume:5 | Issue:2|Papers Count:10

Emulsion stability, viscoelastic rheological properties and particle size distribution of French dressing samples formulated with two types of commercial modified starch have been investigated. The product’s usual thickening agents, xanthan and guar gum, were 100% substituted by (2, 2.2%) of acetylated distarch adipate (ADA) and hydroxypropylated distarch phosphate (HDP) from waxy maize starch. The samples with 2% hydroxypropylated distarch phosphate starch showed the minimum emulsion stability (<95% after three months of storage) and were eliminated from further studies and the other three samples along with the control were selected for particle size distributions and dynamic rheological properties analysis. The sample formulated with 2.2% of HDP starch showed a better storage stability (higher zero shear viscosity), deformability (gLVE) and greater texture strength (G’0) due to more structural entanglement and intermolecular hydrogen bonds as compared to the other type of commercial starch and control. In particle size distribution curve of this sample a broad and distinguished peak with higher percentage of population ranging from 10 to 100 <m was observed which might be due to the higher water absorption and more swollen/degraded starch granules. The area-based average diameter (d3.2) of the particles confirmed more similarity between this sample and control.

Raw cane sugar is one of the most important product in the sugar industry and is the main raw material for the white sugar production. Morphological and physical properties of this product might influence the final white sugar. For instance, the behavior during centrifugation, transport and storage is related to the characteristics of these crystals. The object of this study was to determine the morphological factors in raw cane sugar using digital image processing. For this purpose, two sets of imported and domestic raw cane sugars were collected and different factors related to the area size, perimeter, squareness and crystal count were determined. The results showed that the mean area for the imported sets of raw sugars was 154.1994 pixel while for the domestic sets was 220.6249 pixel. This parameter reflects the size of crystals. Perimeter and squareness characteristics and count of crystal in 0.5 g sample were also demonstrated. The results of this study demonstrated that digital image processing technique might be regarded as a useful way to determine the physical and morphological characteristics of different raw sugar crystals.

Protein recovery under sonication treatment and autolysis, also protein hydrolysis progress during enzymatic hydrolysis (using trypsin and chymotrypsin) and autolysis (using endogenous enzymes) were investigated in Saccharomyces cerevisiae and Kluyveromyces marxianus. Crude protein content of dried yeast cells were 53.22% and 45.6% for S.cerevisiae and K.marxianus, respectively. After 96 hrs of autolysis in the presence of ethyl acetate, protein recovery reached 59.74% and 77.18% for S. cerevisiae and K. Marxian us, respectively and it was 53.66% and 55.17% for sonication treatment. The yeast protein solution obtained by sonication was hydrolyzed by trypsin and chymotrypsin. Autolysis, produced hydro lysates with higher degree of hydrolysis (DH) values as compared to the enzymatic hydrolysis. After 96 hours autolysis, DH increased to 48.75% and 39.51% for S. cerevisiae and K. marxianus respectively. Chymotrypsin was significantly more effective on K. Marxian us protein with the DH value of 21.59%, but the effect of trypsin was the same in the two yeast strains (DH value of 18.5%). It can be concluded that the autolysis process is significantly more effective than enzymatic hydrolysis by producing smaller peptides.

There is a growing interest in food industry to replace the synthetic chemicals by the natural products with bioactive properties from plant origin. The aim of this study was to determine the chemical composition of Mentha pulegium essential oil and to characterize the antimicrobial activities of the essential oil. The essential oil of Mentha pulegium was analyzed by GC-MS. The evaluation of the antimicrobial activity on Proteus mirabilis ATCC 15146, Bacillus subtilis ATCC 12711 and Zygosaccharomyces rouxii ATCC 14679 was determined by Minimum Inhibitory Concentration procedure. The sensitivity of microorganisms was also measured by disc diffusion and cup plate methods. The essential oil of Mentha pulegium revealed pulegone, cineole and piperitenone were the main constituents, comprising 19.89%, 19.38%% and 15.14% of the essential oil, respectively. The results showed a significant antimicrobial activity against microorganisms especially Bacillus subtilis, while the least susceptible microorganism was Zygosaccharomyces rouxii (P<0.05). The minimum inhibitory concentration of the essential oil of Mentha pulegium was 0.5%, 1.25% and 1.5% for Bacillus subtilis, Proteus mirabilis and Zygosaccharomyces rouxii respectively. In this research work, Bacillus subtilis bacteria was more sensitive to the essential oil than Proteus mirabilis. In general, this study indicated that the essential oil of Mentha pulegium has remarkable antimicrobial activity on microorganism especially gram positive bacteria. Related researches are required to assess the efficacy of this essential oil in therapeutic applications.

Besides the high starch content, sweet potato contains endogenous amylases where the two Predominants are µ and b amylases. Sweet potato is thought to be a promising source of b amylase since b amylase is one of the major protein in the tubers. This investigation has focused on the properties of b amylase from white-flesh sweet potato that has been grown in Iran as a potential source for industrial applications. Protein was determined using Bradford method and the enzyme activity was evaluated by monitoring of starch hydrolysis by determination of reducing sugar. The effect of pH and temperature on the enzyme activity and stability was determined. b amylase had optimum pH of 5.5 and was stable from pH of 3.5 to 7.5 with the maximum activity at 55°C.

Vibrio species are the major seafood-borne bacteria that are frequently associated with the consumption of contaminated sea food. A total of 113 samples including 58 fish and 55 shrimps were studied for the possible contamination with Vibrio species. A biochemical protocol was applied for the identification of the Vibrio isolates and Polymerase Chain Reaction (PCR) was carried out to confirm the strains. The results indicated that 25 samples (22%) were contaminated with Vibrio species. Among Vibrio isolates, Vibrio harveyi was the species most frequently isolated (11.5%), followed by followed by V. parahaemolyticus, V. vulnificus, V. alginolyticus and V. mimicus. Vibrio cholerae was not detected in the studied samples. The results of this study indicated that fish and shrimp from the Persian Gulf regularly contain pathogens that might affect the public health.

Regarding the nutritional value and availability of acorns in west and southwest of Iran, the effects of partial substitution of wheat flour with acorn flour was investigated. Wheat flour was replaced by treated acorn flour in the formulation of sponge cake and the quality characteristics were evaluated. Density of cakes was increased with increasing the acorn flour. As the substitution degree was increased the textural parameters such as hardness, adhesiveness, gumminess and chewiness were increased and some other characteristics including springiness and cohesiveness were decreased. Sensory attributes also diminished as the concentration of acorn flour increased. Heat treatment of acorns did not exhibited significant effect on the cakes quality. Based on the results obtained in this research work, in order to make the cake as a functional food, lower levels of substitution (less than 10%) had acceptable texture and sensory properties as compared to the control.

This study is concerned with the viability of producing biodiesel from waste beef bone fat and evaluate this product according to the quality requirements defined by ASTM D- 6751. Accordingly, beef bone fat was heated to remove the moisture under vacuum at 60oC Alkaline Catalysed Transesterfication was carried out by using 6:1 molar ratio of ethanol to fat in the presence of 1% w/w sodium hydroxide, at 78oC for 2h. Acid- Catalysed Transesterfication reaction of beef bone fat was carried out using 30:1 molar of ethanol to fat in the presence of 1% sulfuric acid at 78oC, for 69h. Two- stage acid base trans esterification is also carried out for biodiesel production. The resulted biodiesel from alkaline reaction meet the quality requirement better than the acid reaction but both biodiesel did not comply with the European Standard parameters namely kinematic viscosity, specific gravity, density, and cloud point.

The aim of the present study was to investigate the physico-chemical quality of raw milk of one-humped camel coming from Khur and Biabanak known as a camel-rearing area located in Isfahan province of Iran. 500 milliliters of raw milk from thirty individual one-humped camels were randomly collected and subjected for proximate analyses indicating the amounts of total solid, protein, fat, lactose, ash, acidity and pH that were 11.24±0.41%, 4.61±0.5%, 2.72±0.54%, 3.05±0.4%, 0.86±0.07%, 0.12±0.002% and 6.52±0.18 respectively. The mean values of calcium, zinc, magnesium, and iron were demonstrated to be equal in respective order of 79.18±0.58, 0.78±0.6, 1.44±0.14 and 0.69±0.33 mg.100 g-1. Analysis of the physical properties revealed that the specific gravity, L*, a*, b*, whiteness and yellowness of the milk were 1.025±0.009, 77.74±0.67, -0.90±0.37, 2.492±0.27, 39.3±0.91 and 4.81±1.06 respectively. According to the results mentioned earlier, it might be concluded that the raw milk produced from one-humped camels reared in Khur and Biabanak could provide a valuable source of energy for the consumers.

World population has been continuously raised and therefore due to this fact new source of foods, particularly proteins, are in demand. In recent years, single cell protein has been considered as an accepted substitute for animal and plant proteins. In this study, single cell protein production was studied in a batch submerged culture using Aspergillus niger PTCC5012. Experimental design was performed by Qualitek-4 software using Taguchi as a fractional factorial statistical method. Glucose, magnesium sulfate and potassium hydrogen phosphate concentrations as well as the pH were considered to be the four key parameters, each one at four different levels. Optimal conditions were created to achieve the maximum single cell protein of Aspergillus niger PTCC5012 in respect of the optimum concentrations of the mentioned parameters. An acceptable consistency of 94% was observed between optimum single cell protein proposed by the software and the experimentally measured one. Glucose concentration was evaluated as the most effective parameter on single cell protein production yield with 40.95% contribution. The concentration of potassium hydrogen phosphate was introduced as the less effective factor on single cell protein production with 13.99% contribution.