JOURNAL OF FOOD HYGIENE
Year:2017 | Volume:7 | Issue:3 (27) |Papers Count:8

Numerous attempts have been made to replace calf rennet with another milk-clotting protease because of limited supply and the high price of calf rennet.Biarum carduchcorum is rich in protease activities, therefore it is a probable candidate for substitution. No systematic study on the Biarum carduchcorum and its enzyme characteristics have been conducted so far. The purpose of this study was to prepare Biarum extract, determination of its protease activity for milk clotting and production of Iranian white cheese and study on the physicochemical and organoleptic properties of the product. After the cheese production by the vegetable extract (0.5% concentration) organoleptic, textural properties and nitrogen solubility index (NSI) were analyzed during 45 days of ripening compared to the control sample. The results of this study showed that the optimal protease activity of the extracted enzymes for milk clotting was at 45oC, pH=5 and 15 mmol/ml concentration of CaCl2.The cheese sample that was manufactured with vegetable enzyme had a bitter flavor and sharper odor. At textural analysis, the cheese had a lower hardness. Assessment of proteolysis during the cheese ripening by NSI measurement showed that the proteolysis severity of cheese sample produced with vegetable enzyme was significantly higher than the control sample. Therefore, it seems that aqueous extract of Biarum in concentration used for the production of Iranian white cheese cannot be a suitable substitute for rennet.

The aim of this study was to introduce a new method for producing ZnO/silica gel nanocomposites ZnO/silica gel. Nanocomposites were synthesized by inserting silica gels in a molten bath of zinc sulfate (at 560oC) for different contact times. Except for zinc sulfate, no reduction agent or chemical material was used for the preparation of nanocomposite. In this method, synthesis of nanoparticles and their immobilization on the substrate were carried out in a period of time less than 60 minutes. The ZnO/silica gel nanocomposites were studied by scanning electron microscopy (SEM) and UV–visible diffusive reflectance spectrometer (UV–Vis DRS). The SEM micrograph showed that the contact of silica gel with molten salt resulted in the formation of nanoparticles on the silica gel surface. On the other hand, by increasing the contact time, ZnO nanoparticles loading was increased. The antibacterial test against E. coli revealed that nanocomposites produced by 60 min contact duration, reached a mortality rate of 99.85%. The leaching test demonstrated the stability of the nanocomposites, and the delivery of zinc in water was less than 1.5% for all samples.

Edible colors are materials which in the case of adding to food and drinks cause transferring color to them. Most of these colors are not acceptable in terms of applying in human food and underlies various diseases like gastrointestinal disorders, renal, liver and blood toxicity. The goal of this study was investigating the efficiency of improved alumina by sodium dodecyl sulfate (SDS) in eliminating Tartrazine from aqueous environments. In this research, the impact of effective parameters such as initial concentration of Tartrazine, time, pH, alumina dose and SDS value were studied in order to approach an optimal condition for eliminating the color. Also, absorption behavior was evaluated by Freundlich and Langmuir isotherms. The highest efficiency of Tartrazine elimination in the solution resulted in optimal pH of 2, the amount of adsorbent 1.5 g/L, 16 min duration and value 0.04 SDS g/l which was obtained for dye concentration 5 mg/L about 94.13%. Also, results suggested that Tartrazine absorption follows Langmuir isotherm (R2=0.9867). Obtained results from thermodynamic studies such as Gibbs free energy (-5.728 Kj/mol) and enthalpy (-85.86 Kj/mol) and entropy (-271.102 J/mol.K) also suggested that the absorption process was exothermic. The results of this research suggested that improved alumina by sodium dodecyl sulfate had a relative good capability in Tartrazine elimination from aqueous environments. Thus applying this technique for eliminating color pollutants from aqueous environments is suggested.

Herbs are often produced by traditional methods and in poor sanitary conditions and can contain high amounts of spoilage and pathogenic microbes. The aim of this study has investigated the effect of ozone on some qualitative characteristics and microbial spices sumac, cumin and pepper. For this purpose, samples were treated by ozone at a concentration of 2 g per hour for 10, 20, 40 and 60 minutes. Then microbial count and chemical characters such as moisture content, antioxidant properties, and phenolic compounds were determined. The results showed that compared with controls, treatment with ozone decreased 2 logarithmic units (P<0.05) the total number of microorganisms, 4 logarithmic unit mold and yeast populations, and 1 logarithmic unit coliform. On the other hand, 60-minute treatment with ozone caused a significant reduction (P<0.05) the amount of moisture in the cumin and pepper But this was not statistically significant reduction in sumac. After treatment as well as 60 minutes of ozone, the number of phenolic compounds in cumin and pepper significantly was fell compared to control (P<0.05) While there was no significant reduction in sumac. In the case of the antioxidant index (percentage of Scavenging of DPPH radical) Results showed that At time zero and after 60 minutes of treatment with ozone, the highest antioxidant activity respectively was observed in crushed spices, pepper, and cumin. According to the findings, we can ignore the negative effects of ozone on some qualitative features of spices, used it effectively to reduce microbial seasonings.

This study was conducted to determine the quantity of sodium benzoate and potassium sorbate in 61 industrial dough samples (16 different brands with a different production date) in Shiraz market. Moreover, chemical characteristics of the samples (pH, SNF, fat and salt content) were determined. The mean concentrations of potassium sorbate and sodium benzoate were 31.84 and 31.83 mg/kg, respectively. Based on Iranian National Standard (No 2453), none of these preservatives are permitted to be used in the dough. According to the results, 73.8% and 85.3% of the samples contained potassium sorbate and sodium benzoate, respectively and consequently inappropriate for consumption. Moreover, pH, salt, fat and SNF contents in 100%, 95.1%, 70.5% and 100% of the samples were found in the acceptable limit, respectively. Among the samples, 11.5% had potassium sorbate and 23% had sodium benzoate, and 62.3% contained both of the preservatives. There was no significant correlation between the concentration of sodium benzoate and the shelf life of the samples. However, there was a significant correlation between the concentration of potassium sorbate and the shelf life (r=0.37, p=0.001). Despite the Iranian National Standard legislation, presence of these chemical preservatives in dough could be a public health concern.

This study was performed to evaluate the effect of different cooking methods on the level of iron, copper, zinc, and nickel in the muscle of Cyprinus carpio. For this purpose, 75 samples of fish with different sizes were obtained from Azadegan Aquaculture Center in Ahvaz. The samples were digested through the wet-digestion method and the concentrations of the essential elements were measured by Atomic Absorption Spectrophotometer. According to the results, fried and steamed samples had the highest (3.54±0.31 mg/100g wet weight) and lowest (1.64±0.11 mg/100g wet weight) concentration of iron. The highest and lowest concentration of zinc was recorded in the fried (1.74±0.09 mg/100g WW) and steamed (1.24±0.09 mg/100g WW) samples, respectively. In the case of copper, the highest (0.12±0.09 mg/100g WW) and lowest (0.07±0.003 mg/100g WW) concentration were recorded in the micro-waved and steamed specimens, respectively. The results for nickel was determined as 0.023±0.001 mg/100g WW and 0.016±0.0002 mg/100g WW in the fried and grilled fishes Moreover, the highest and the lowest level of essential elements which were recorded among the samples belonged to iron and nickel respectively. In all samples, the level of iron was recorded below the FDA limit. In addition, in all samples, the level of nickel, zinc, and copper was estimated below the maximum acceptable limit of WHO, MAFF, NHMRC, and FAO.

Hydroxymethylfurfural (HMF) is one of the compounds formed due to the heat treatment and storage of honey and the maximum level of HMF in honey have been set in 40 ppm under codex standards. In this study, the effects of heating temperature (55, 65 and 75oC), heating duration (10, 20 and 30 min) as well as storage temperature (25 and 40oC) were assayed during the three months of storage, based on response surface methodology. The effect of the above-mentioned variables on physicochemical properties (Lab color factors, pH, and moisture) and HMF content (based on spectrophotometric technique) of the samples was studied. Prediction model of each treatment was calculated. The outcomes during the 45 and 90 days of storage were analyzed. Results showed that temperature, time of heat treatment and storage duration had no effect on pH, moisture content, and color; while storage temperature had a significant effect on L* and a*. HMF content was affected by of all the variables so that its rate was increased significantly with increasing thermal process and storage time. Among the studied samples, HMF content was exceeded the standard limit in the sample heated at 75oC for 20 min and kept at 40oC for 90 days. The optimal level of HMF resulted by heating at 55oC for 10 min and under the storage temperature of 25oC for 45 days.

Aflatoxin, as one of the most potent carcinogen, is considered an important threat for public health, and it is not possible planning for reducing aflatoxin M1 (AFM1) levels in milk and milk products without paying great attention to the exposure to these compounds. This survey aimed to investigate the occurrence of AFM1 in pasteurized milk samples produced in Tabriz, Iran. Seventy-four milk samples produced by eleven different factories were collected from local market during six months in fall and winter 2015. AFM1 was analyzed by Enzyme-Linked Immune Sorbent Assay (ELISA). Based on results, 82% of the samples were contaminated with AFM1 in concentration levels ranged 5 to 80 ng/l. In 9 samples (12.16%) the AFM1 level was higher than 50 ng/l, the maximum residue limit (MRL) accepted by Codex and European Union for AFM1 in milk. The difference of AFM1 level between dairy factories was statistically significant (p<0.5). It seems that continuous monitoring of AFM1 contamination in distributed milk is a critical step in control and prevention of this contaminant.