Journal of Food Biosciences and Technology
Volume:7 Issue: 2, Summer-Autumn 2017

Lactic acid bacteria, including lactobacilli, enterococci, leuconostoc and weissella species isolated from Iranian traditional fermented camel milk (Chal) were assessed for the incidence of virulence determinants (gelE, efaAfm, efaAfs, ace, espfs, cylM, cylA and cylB), sensitivity to various antibiotics and virulence phenotypes. The incidence of virulence genes was determined by polymerase chain reaction and antibiotic susceptibility was tested by disk diffusion method. The results of this study indicated that all of the strains harbor at least two or more of the virulence genes. The most frequent virulence genes detected among tested strains were cylB, gelE and efaAfs. All strains showed no β-hemolysis while tyrosine decarboxylase activity and gelatinase production were observed in enterococcus and leuconostoc strains. Majority of strains were resistant to Polymyxin B and kanamycin. Lactobacillus strains including L. paraplantarum, L. kefiri, L. paracasei, L. plantarum and Weissella cibaria were resistant to both vancomycin and kanamycin. The possibility of transferring the antibiotic resistance and virulence genes to other starter and commensal strains makes the usage of these strains in food and dairy products controversial without required safety assessments.

The aim of this study was to investigate the influence of different parameters on exopolysaccharide (EPS) production from Enterobacter cloacae subsp. dissolvens using seawater as a basal medium. For this purpose, the effect of carbon (sucrose, molasses, paraffin and sunflower oil) and nitrogen sources, NaCl concentration, incubation time, pH as well as seawater dilution or enrichment with distilled water or Aloe vera, respectively on EPS production was investigated. Incubation of bacteria at 30°C in the seawater for 24 hours resulted in 0.56% EPS production. Increasing the incubation time from 1 to 4 days led to a decrease in biopolymer production. EPS yield was not affected by the addition of sucrose, pH (6-8) or by bacteria inoculation in brine (1-4% NaCl). Dilution of seawater with different ratios of distilled water (1:2, 1:1 and 2:1) or seawater enrichment with various concentrations of Aloe vera leads to EPS yield reduction. Polymer production was drastically increased with sunflower (to 5%) or paraffin (to 3%) concentration. The interactions between different parameters on EPS production in the formulated mediums with distilled water were studied. The results showed that EPS production was reduced significantly in the formulated mediums containing different concentrations of water, NaCl, nutrient broth, glucose, ammonium sulfate and potassium phosphate. Among different formulations, the highest yield (0.27%) was achieved with the formulation of distilled water, 3.4% NaCl, 1% paraffin and 0.05% KH2PO4, indicating that simulation of seawater using formulated distilled water didn’t provide comparable results. Therefore, paraffin and sunflower oil would be the matter of choice due to their higher productivity.

Sugar juices in the production of beet sugar contain complex varieties of colored materials that have not been identified completely. Color of the sugar depends the color of juices from which sugar is produced. The mechanisms concerning color formation in beet sugar processing are complicated due to many parameters involved. The main mechanisms related to the color formation during purification stage are the Maillard reaction and alkaline degradation of invert sugars, but caramelization is more important in thick juices. In this study, gel-permeation chromatography (GPC) is used to separate and determine some color components in raw, thin and thick sugar beet juices. Subsequently, the separate components are detected by a UV coupled to a refractive index (RI) detector in series. GPC is a suitable technique for determining the molecular weight distribution of compounds in juices and can be used to demonstrate colored compounds through the sugar beet processing. GPC chromatography, using UV and RI as detector, is the analytical method proposed to study the nature of colored impurities and to characterize the stages of the process where colorants are generated. The results show that all of the juices in this study had low molecular weight colorant in the range of 0.2 up to 10 kDa.

Seaweeds contain high levels of minerals, vitamins, essential amino acids, indigestible carbohydrates, and dietary fiber. The objective of this study was to compare Spirulina seaweed yellow alkaline noodles made with different levels of green seaweed to make Yellow alkaline noodle products of high nutritional quality with rich fiber content. Green seaweed powder (Spirulina) was incorporated in different proportions (0, 5, 10, 15%) in noodles. Proximate compositions (protein, fiber, ash, fat, moisture), pH, color, textural intensities, cooking properties (Cooking yield, Cooking loss), and sensory qualities of noodles were evaluated. The results of noodle formula development showed that as the amount of Spirulina seaweed powder increased, the stickiness of the noodles decreased and the appearance became darker. The crude fiber contents of Spirulina seaweed yellow alkaline noodles increased by the addition of Spirulina seaweed powder. Thus, edible seaweeds such as Spirulina might be used as a food supplement to improve the nutritional recommended daily intake.

In this study the rheological and physicochemical properties of four types of honeys, two poly floral (Mountain, Forest) and two mono floral (Sunflower, Ivy), were investigated. Rheological characteristics of honeys were evaluated at different temperatures (10, 15, 20, 25 and 30ºC). All the honeys exhibited Newtonian behavior for shear rate in the range of 1.045-41.8 s-1. The viscosity of samples varied between 1.70 and 270.48 Pa.s according to the kind of honey and the temperature of measurement. The temperature dependence of viscosity was described using the Arrhenius and the Vogel–Taumman–Fulcher (VTF) equations. The values of flow activation energy varied between 89.716 and 112.189 kJ/mol. Two models (Power Law and Exponential models) were also investigated to describe the concentration dependence of viscosity. The samples were found to be different from each other in moisture content, ºBrix, pH, ash, conductivity, free acidity, diastase activity, hydroxymethylfurfural content and sugar content values. The water content of honey samples was between 15.25–19.92 g/100 g.

The aim of this study is to develop an extraction method for the producing of a safe and efficient source of antioxidant compounds from fresh and pre-treated sweet orange (Citrus sinensis cv shahsavari) peel. Three types of solvents (100% ethanol, 100% water and ethanol-water mixtures at the ratios of 35:65 and 65:35, v/v), three duration times (60, 120 and 240 min) were chosen as the parameters affecting the phenolic compounds and flavonoid contents, extraction yield and antioxidant activities. These properties were evaluated by using the Folin-Ciocalteu method, DPPH radical scavenging activity assay and the aluminum chloride colorimetric method, respectively. The results showed that the extraction times within the current range of 60-240 min have no significant effect on the investigated properties. The binary water-ethanol mixture at the ratio of 65:35 showed the best extraction yield for total phenolic compounds of fresh orange peel. The lowest IC50 and the highest antioxidant activity observed in this extract sample indicated a possible synergistic effect among the phenolic compounds with different polarities. Pretreatment of the orange peel by liquid nitrogen resulted in maximum antioxidant activity that may be related to the releasing the bounded phenolic compounds.

Nowadays, high standard level of living has led to an increase in demand for foods which are minimally processed via high sensory and nutritional quality and also an extended shelf life. High pressure processing (HPP) is one of the techniques that was considered for food preservation at the first application in food industry. Pressures in the range of 300 to 650MPa have been found to affect the micro-organisms, although, there is an exception regarding spores inactivation. Many studies have proved that although the application of high pressure between 400-600MPa in raw milk does not result in a product with equivalent quality as sterilized milk, but, it gives the same quality as pasteurized milk. In addition, it has been proved that high pressure creates important roles in dairy processing. For example, it improves acid coagulation in order to accelerate cheese ripening. This review summarizes some significant studies concerned with the application of HPP for cheese ripening acceleration.

Lactic acid production in a batch submerged fermentation process by five Lactobacilli: bulgaricus, casei, lactis, delbrueckii and fermentum in lactose fortified whey culture were investigated. Kinetic behavior of Lactobacilli growth rate and lactose utilization was studied based on the Moser and Gompertz kinetic models. Trendline tool in Excel software was applied for fitness assessment of the experimental data to investigate the kinetic models. Lb. bulgaricus had shown the best cell production yield of 0.119 g.g-1 of consumed lactose. Also, maximum lactic acid production yield of 0.602 g.g-1of consumed lactose was obtained by Lb. bulgaricus.  Lb. bulgaricus (R2=0.954, μmax=0.5 and Ks=9.385) and Lb. casei (R2=0.956, μmax=0.580 and Ks=18.2) have showen acceptable consistency with Moser kinetic model. Moser kinetic model isn't a desired model to describe the cell growth and substrate consumption behavior of Lb. fermentum, Lb. delbrueckii and Lb. lactis. None of the investigated strains have shown acceptable consistency with Gompertz kinetic model, therefore, this model isn't known as a good model to describe the cell growth and substrate utilization behavior of Lactobacilli.

Food borne diseases are considered as the major problems for public health in the world and salmonella serotypes are the most important pathogens causing these types of diseases. Present study was carried out for the isolation of salmonella and determination of their antibiotic sensitivity and serovars from local, industrial and breeder poultry eggs. In this cross-sectional survey, 300 samples of local, industrial and breeder poultry eggs (each containing 100 samples) were collected from Tabriz city, Iran and transferred to the laboratory of food hygiene, Islamic Azad University of Tabriz. Isolation of salmonella from egg yolk was performed according to the Iranian National Standards. For definitive detection of salmonella, Biochemical tests, serotyping, and PCR tests were performed followed by Antibiogram test. From a total of 300 analyzed eggs, just 3 out of local samples (3%) were contaminated with salmonella enteritidis. 100 percent of isolates were sensitive to Ciprofloxacin, Gentamycin, Neomycin, Trimethoprim and Sulfamethoxazole. All of the isolates were found to be resistant to at least 5 of 9 evaluated antibiotics. According to the results of this study, the rate of contamination in local eggs supplied and distributed in Tabriz was %3 but the industrial and breeder poultry eggs were recognized safer for public use. According to these findings, it is therefore recommended to pay further attention to cold storage of local eggs.

The consumption of canned tuna in the country has been increasing and some factors are effective on the chemical and organoleptic qualities of this product during transport. The aim of this project is to study methods to reduce histamine and improve the organoleptic properties of the product. Three thawing methods consisted of immersion, cold water shower and open air has been considered. Beside, two storage conditions at -18 and 4 °C were chosen to examine histamine, TVN, pH and organoleptic properties of the canned tuna.  The results indicated an increase in the microbial load at 4 °C as compared to -18 °C and also showed that the formation of biogenic amines is certainly affected by the temperature (P < 0.05). According to the results the presence of viscera led to accelerate the spoilage of the fish and organoleptic properties. According to the results cold water shower might be considered as the best way of thawing (P < 0.05).