Acute and chronic toxicity of ammonia in Persian sturgeon, Acipenser persicus, fingerlings

In the present study, susceptibility of Persian sturgeon, Acipenser persicus, to un-ionized ammonia (UIA) was studied. Fish with an average weight of 5.52±0.45 g were exposed to different concentrations of un-ionized ammonia (UIA) to determine median lethal concentration (96-h-LC50). The fish were exposed to six different concentrations of UIA (control, 0.16, 0.31, 0.62, 0.94 and 1.25 mg/l UIA). The control group was not challenged with ammonia (0.0008 mg/l UIA). The results showed that the 96-h-LC50 of UIA in Persian sturgeon was 0.46 mg/l. According to 96-h-LC50,mid-term exposure to sub-lethal UIA was examined. In the chronic examination, the fish were exposed to different levels of sub-lethal ammonia; control (0.0008 mg/l UIA), 10% of LC50 (0.05 mg/l UIA), 5% of LC50 (0.025 mg/l UIA) and 1% of LC50 (0.005 mg/l UIA) for 30 days. Final length, final weight, weight gain, specific growth rate, daily weight gain and body weigh index decreased significantly in the fish exposed to 0.05 and 0.025 mg/l UIA. According to the results, conversion ratio and condition factor indices were higher in the fish exposed to 0.005 mg/l UIA and control group compared with the fish exposed to 0.05 and 0.025 mg/l UIA

Rheological and structural properties of enzyme‐induced gelation of milk proteins by ficin and Polyporus badius

The rheological and microstructural characteristics of ewes’ milk curd obtained by coagulating with milk‐clotting enzymes, including ficin extract and Polyporus badius were evaluated. The gelation of milk was examined by small amplitude oscillatory shear measurements (SAOS). Different concentrations of ficin and P. badius extracts (1, 3, and 5%) were utilized to coagulate milk proteins. The ewes’ samples containing ficin and mushroom enzymes were heated from 25 to 45°C at a heating rate 1°C/min and kept for 30 min. Then, the curds were cooled down to 25°C with the same heating rate. The ficin extract could induce stronger gels at 45°C and 5% ficin. Similar results were also found for 5% P. badius extract and incubation at 45°C. However, P.badius gels achieved a network with more viscous characteristics and had a softer texture than ficin gels. Therefore, it may be concluded the induced gels with mushroom had higher moisture and lower protein contents, which related to the high proteolytic activity of P. badius. The microstructure survey showed that the mushroom‐induced gel had a more compact structure. By increasing enzyme concentration, both gels showed a coarser and more compact protein network. Whereas, the P. badius gels had more fusions and folds which indicate the greater proteolysis occurred during gelation and there was greater breakdown of protein. Our findings suggest the application of ficin and P. badius enzymes to develop a novel procedure to coagulate milk proteins and providing new structures in food systems

Electroanalysis of tert-butylhydroquinone in food products using a paste electrode enlarged with single wall carbon nanotubes as catalyst

In this study, an electrochemical sensor was introduced as a simple and fast electro­analytical tool to monitor and sensing of tert-butylhydroquinone (TBHQ) in food products. The suggested electrochemical sensor is fabricated by modification of paste electrode (PE) by single wall carbon nanotubes (SWCNTs) as nanocatalyst. The oxidation current of TBHQ was improved by about 2.62 times and its oxidation potential was reduced by about 50 mV after using SWCNTs as conductive catalyst on a carbon paste matrix. The oxidation current of TBHQ showed a linear dynamic range of 0.05 to 390 µM in the sensing process using SWCNTs/PE as the electroanalytical sensor. On the other hand, SWCNTs/PE successfully monitored TBHQ with a detection limit of 10 nM at optimum conditions. The real sample analysis data clearly showed a recovery range of 97.2 to 104.3 %, which is very interesting for a new analytical tool in the food-sensing process

Microbiological and Physicochemical Properties of Raw Milk Produced from Milking to Delivery to Milk Plant

The aim of this study was to determine the microbiological and physicochemical properties of raw milk in Mazandaran province, Iran, during 6 months from winter 2013 to spring 2014. A total of 253 raw milk samples were collected, from dairy farms, milk cans, milk collection centers, and delivery milk tankers. The samples were analyzed for microbial quality, total plate count (TPC), and physicochemical properties including titrable acidity, pH, content of fat and protein, solids nonfat (SNF) level, specific gravity, percentage of water adulteration, and alcohol testing. The mean of TPC was 48×107 CFU/mL. The higher TPC (23×108 ) was found in Chalous city during winter season. TPC less than 106 was used as a basic standard limit by Institute of Standards and Industrial Research of Iran (ISIRI). Significant effect of region was observed on all physicochemical properties except pH (p<0.05). The mean counts of titrable acidity, pH, fat, protein, SNF, specific gravity, and percentage of water adulteration were 15.38, 6.66, 3.42%, 3.04%, 8.33%, 1.029 and 2.11%, respectively, and alcohol stability result of 22.1% of the samples was positive. It can be assumed that raw milk in the study area had poor bacteriological quality according to the Iranian National Standard ( (ISIRI); therefore, it may be hazardous for human consumption. This finding shows the necessity to implement good hygiene practices

Rheological, textural and structural properties of dairy cream as affected by some natural stabilizers

Abstract The effects of whey protein, basil seed gum (BSG), and κ-carrageenan (CGN) on the structure–rheology interactions of low- and high-fat cream were investigated. Pseudoplastic and thixotropic behavior of cream was found for all the samples and the pseudoplasticity was increased with an increased level of stabilizers. The apparent viscosity (η a) of the forward curves is greater than that of the backward ones, which may be the result of the breakdown of the fat globule structure under shear stress. The viscosity of cream was reduced, while using a stabilizer (BSG/CGN) can be related to the water binding of hydrocolloid molecules contributing to resistance in flow. For all samples, elastic modulus was greater than viscous modulus, indicating a greater contribution from elastic characteristics. With the increase of BSG/CGN levels, the molecules may be competitively adsorbed onto the surface of fat droplets, thereby changing its surface tension and decreasing its particle size. Increases in whey proteins, fat, and BSG also significantly increased hardness, whereas increases in CGN significantly decreased it. The globular aggregates in the microstructure of high-fat dairy cream were smaller than those in low-fat dairy cream, allowing more water to be retained in the high-fat samples. Therefore, synergistic interactions between polysaccharides and proteins may encourage the formation of a cross-linked network

Physical and Rheological Properties of Egg Albumin Foams Are Affected by Ionic Strength and Basil Seed Gum Supplementation

In this study, the effect of ionic strength and basil seed gum (BSG) on the foaming properties of egg white albumin (EWA) was studied. The foam was prepared with 1% EWA (w/v) in the presence of different concentrations of sodium chloride (NaCl; 0, 0.5, and 1% w/v) and BSG (0, 0.1, and 0.3% w/v). The results showed that foam density and foam stability of EWA significantly (p<0.05) increased with an increase in BSG concentration (from 0 to 0.3% w/v). On the contrary, an increase in NaCl concentration (from 0 to 1% w/v) increased foam overrun but decreased foam density. Amplitude rheological parameters indicated an improvement in foam structure with increasing NaCl concentration. In addition, an elastic structure was obtained in the case of the foams with the higher concentrations of NaCl. Elastic modulus (G′) was higher than loss modulus (G″) in the frequency range, and there was low frequency dependency in all of the samples. In constant frequency of 1 Hz, tangent (δ) was the lowest in the sample containing 1% NaCl (w/v), but without BSG. There was a decrease in yield stress values with increasing BSG concentration; however, the increase in NaCl concentration led to an increase in yield stress. The highest yield stress (37 Pa) belonged to the sample containing 1% NaCl, but without BSG. Overall, it was found that both NaCl and BSG could substantially improve the rheological and foaming properties (in particular, foam stability) of egg white albumin