Journal of food science and technology
Year:2015 | Volume:12 | Issue:48|Papers Count:24

Shrimp is one of the high spoilage seafood that keeping its quality after harvesting is the most important problems to aquatic product industry. The aim of this study is to evaluate the effect of icing on the quality and shelf life of Litopenaeus vannamei. After harvesting, shrimp was dipped in sodium metabisulphite solution. Then, divided in immediately icing and 2 hours delay icing treatments. Microbial (MBC, PTC), chemical parameters (PV, TBA, TVB-N) and sensory analysis were measured at 0, 3, 6, 9, 12 and 15 days. The psycrotrophic bacteria and mesophilic counts of 2 hours delay were more than those of the immediately treatment. The mesophilic counts were more than psycrotrophic bacteria in the first days of storage but the psycrotrophic bacteria more increase in comparison to mesophilic during storage. Chemical parameters of immediately icing treatments had a slower growth than the 2 hours delay. Sensory index reduced during storage. Results of this research show that immediately icing was significantly effect on shelf life of Litopenaeus vannamei. Then the shelf life of shrimp was 9 and 12 days in 2 hours delay and immediately treatments respectively.

There is not enough information about postharvest physiological behavior and optimum storage temperature of cultivated persimmons in Karaj region of Iran. In this study, persimmon fruit, cv. Karaj, was harvested at mature stage and was treated with hot waters at 45 and 50oC for 20, 30 and 45 min. Besides, one lot of fruit was bathed at 25oC for 30 min as control treatment. The physiological behaviors of treated fruits were monitored during 4 months storage at 0, 2 and 5oC. Results showed that severity of symptoms, such as; skin browning index, fruit softening, fungal disease incidence and loss of color indices (L*, a*, b*), were higher in storage at 2 and 5oC than storage at 0oC. Therefore, Karaj persimmon was tolerant to 0oC for storing purpose. On the other hand, hot water treatments at 45oC for 30 and 45 min and 50oC for 20 min maintained fruit firmness and color properties, and controlled disease incidence better than that of control and hot water treatment at 45oC for 20 min. However, hot water treatment at 50°C for 30 and 45 min, in spite of maintaining suitable colour properties, contrary with other effective treatments caused to fruit skin browning and had notociable fungal disease. Therefore, hot water treatments at 45oC for 30 and 45 min and 50oC for 20 min are the recommendable treatments for increasing postharvest life of Karaj persimmon.

In this research a new laboratory solar-vacuum dryer was designed and fabricated to study drying behavior of pomegranate arils with heat source of solar energy. Drying of the samples was implemented at the absolute pressures of 10, 20, 40 and 60 kPa. Impact of different absolute pressures on moisture loss trend, effective moisture diffusivity, color and shrinkage of pomegranate arils, dried in solar-vacuum dryer was studied. With regression analysis of the applied models, proved that the Midilli model had supremacy in drying behavior prediction of pomegranate arils. Results indicated that with decreasing absolute pressure, drying time was decreased. Minimum drying time was related to the absolute pressure of 10 kPa. Effective moisture diffusivity of the pomegranate arils was estimated at the ranges of 3.09×10-10 to 4.13×10-10 m2/s. Total color changes and shrinkage percent of the pomegranate arils were estimated at the ranges of 17.4 to 22.1 and 67.58% to 74.45%, respectively.

The aquatic zoonotic bacterial Streptococcus iniae represents a threat to the worldwide aquaculture industry. This study was carried out to evaluate the antibacterial activity Cuminum cyminum essential oil and nisin for control of S. iniae in fillets of Rainbow trout (Oncorhynchus mykiss) in 4 Co on basis hurdle technology between 2012 and 2013. The effect of different concentrations of nisin (0, 0.25 and 0.75 mg/ml) and Cuminum cyminum (0, 0.005, 0.135 and 0.405 %) were conducted on growth of S. iniae GQ850377 for 15 days. The results showed that growth of bacterial delayed in samples treated with nisin and essential oil singly to 9 days and together to 3 days. Samples treated with essential oil showed a significant decrease on the growth of the bacteria compared with nisin and control sample (P<0.05). No significant different was observed on the growth of S. iniae in samples treated with higher concentrations of C. cyminum (0.135 and 0.405 %) (p>0.05), but different concentrations of nisin was statistically significant (p<0.05). Synergistic effects were observed at concentration of 0.405% C. cyminum and 0.75 mg/mL nisin.

Iran is the fourth main producer of kiwi fruit in the world but the post-harvest wastage of this valuable fruit is considerable. On the other hand, the microalgae are natural and extraordinary nutritional sources that can be used in the production of functional food. The purpose of this study was the formulation of an innovative product of kiwifruit with high durability and its enrichment with Spirulina platensis algae and investigation of some of physicochemical and sensory properties of this product. In this study, the effects of different levels of Spirulina Platensis micro-algae in four levels (0%, 0.25%, 0.5% and 1%), agar hydrocolloids in three levels (0.25%, 0.5% and 1%) and guar in three levels (0.25%, 0.5% and 1%) on water activity, textural feature and color parameters of kiwi puree- based fruit pastille were studied and the best formulation been selected considering total acceptance and nutritional characteristics including vitamin C, total ash, protein, fat, fiber and iron and calcium content. The results showed that three variable (Spirulina Platensis, agar and guar) significant effect on water activity. Additionaly, the results of coliremetre using Image processing techniques showed that the effects of agar and guar on "a*", "l*" and "b*" were not significant but Spirulina has a significant effect on color parameters on fruit pastilles. Texture analysis showed that agar and spirulina changed gumminess of the samples significantly. According to the sensory analysis, the 0.25% Spirulina, 0.25% agar and 1% guar obtained the highest score of total acceptance.

Active packaging is one of the innovative concepts in food packaging that has been used for controlling environmental parameters such as moisture content in the package. In this study the quality and quantity characteristics of button mushroom were investigated by color, maturity index, opening caps and weight loss after the storage at refrigerator temperature (5±2oC). The treatments included packaging film at two levels: (clear PVC box and stretch PVC), moisture absorber at four levels: and storage time at five levels: (0, 4, 8, 12 and 16 days). Four moisture absorber treatments were included: the first treatment containing silica gel 1.25 g, the secondary treatment silica gel 2.5 g, the third treatment only spongy foam, the forth treatment containing silica gel 1.25 g and spongy foam. The analyses showed that the stretch PVC in comparison to clear PVC films had the lowest open cap mushroom and weight loss. Silica gel (1.25g) treatment and only foam treatment with stretch PVC film had the lowest open cap. The sensorial evaluation showed there was no significant difference between treatments in terms of maturity index. In terms of cap color, judges preferred button mushrooms treatments by silica gel (1.25 g) with clear PVC box and Silica gel (1.25g) with stretch PVC treatments and there were significant differences between them and other treatments.

Production and export of Doogh as a Iranian fermented national drink have increased. Contamination of Doogh by yeasts and molds is one of the defects that results in spoilage and increasing the waste of the product. Drying and convertion of Doogh to its powder by spray dryer is one of the method for increasing the shelf life and decreasing the volume and the costs of transportation.In this study Doogh samples with fat content (0.5% and 1.5%), dry matter without fat and salt (3.5% and 4.5%) and 0.7% salt were first dried in preliminary tests including inlet air temperature (100, 150 and 200oC), liquid feed flow rate (5, 10 and 15 mL min 1) and drying air flow rate (400, 600 and 800 L h). Best condition were adjusted according to the best results of solubility test and were conducted to drying the samples.fat content and dry matter had significant effect on physical, chemical and microbial characteristics of Doogh powder. First and forth formula had highest and lowest solubility. The solubility of first and forth formula was 82.11±0.62% at 25oC and 63.18±0.33% at 15oC respectively.Increasing the fat content results in decreasing the solubility, increasing the particle size and the rate of viable starter counts.

The aim of this study was to evaluate the effect of edible gelatin coating on the quality characteristics and shelf life of fish finger of Hypophthalmichthys molitrix during refrigerated storage. Fish fingers were immersed in coating solutions of gelatin 4% and then dried, packed and stored in refrigerator (4oC). Chemical (moisture, protein, fat, ash, pH, PV, TBA and TVB-N) and microbial parameters (TVC and PTC) were measured at 0, 3, 6, 9, 12, 15, 18 and 21 days. According to the obtained results by increasing of storage time moisture and fat content decreased and pH value were significantly increased (P <0.05). While there was no significant difference between the ash content of control and coated samples (P<0.05). Peroxide value and thiobarbitoric acid of coated samples were lower than the control. The TVB-N value of control and coated samples were 27.80 and 27.46 mg N/100g of flesh fish in 12 days of storage that higher than acceptable value. The total viable count (TVC) and psychrotrophic count (PTC) of fish fingers were significantly increased (P <0.05) during refrigerated storage. The results of this research indicate that the gelatin coating reduces the oxidation, but has no effect in reducing the value of microbial count.

The aim of this study was to evaluate antibacterial activity of aqueous extract of castor seeds (two varieties, Mashhad and Isfahan) on Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922 and Listeria innocua ATCC33090 as food borne pathogens. The sensitivity of the microorganisms was evaluated using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). According to disc diffusion method the most resistance was observed by gram positive bacteria (Listeria innocua, Staphylococcus aureus) whereas, the most sensitivity was observed by Escherichia coli. In disc diffusion method as a positive control Erythromycin, Gentamicin and chloramphenicol were used on Listeria innocua, Staphylococcus aureus and Escherichia coli in which deterrence diameters were 13mm, 22mm, 30mm, respectively. The experiments of MIC, MBC were performed in triplicate. According dilutions which were prepared in MIC experiment the ranges of aqueous extract of castor from Mashhad on Listeria innocua and Staphylococcus aureus was between 40 to 160 mg/ml. This range for Escherichia coli was less than 40 mg/ml. But for aqueous extract in castor seeds from Isfahan was between 20 to 40 mg/ml on Listeria innocua, between 40 to 80 on Staphylococcus aureus and between 20 to 80 mg/ml on Escherichia coli. Also MBC test were measured around 160 mg/ml in castor seeds of Mashhad and Isfahan. The both of aqueous extract of castor seeds from Mashhad and Isfahan had strong antibacterial activity and aqueous extract from Isfahan had more inhibitory effect than the aqueous extract of Mashhad.

In this research, the modeling with Artificial neural network and Multilayer – Perceptron were used in order to evaluate the zeolite and citric acid's usage in reducing of Aflatoxin’s production in stale dry breads across the Mashhad. Since, the stale breads are the main sources of the livestocks’s feeding, and because of the availability of proper environmental conditions for growing molds, these breads are severely contaminated by mycotoxin and especially Aflatoxin, and this make some anxieties about the human being and animal's life. So, the foodstuff's contamination by mycotoxin, should be controlled accurately through the food chain. The results have shown that modelling with ANN is a suitable method especially in food industries, and also the addition of zeolite as compared with Citric Acid, cause the Aflatoxin to reduce more. In this manner, the interaction of zeolite and citric acid caused the Aflatoxin to decrease more, than when zeolite or citric acid are being used alone.Based on these results, Artificial neural network model for zeolite with one hidden layer, hyperbolic tangent function as the transfer function, Levenberg-Marquardt method as the learning rule, 3 hidden neurons, %60 for training subset and %20 for each of validation and test subsets with the correlation coefficient 0.973 had the best overfiting.The modeling results indicate that there is an excellent compatibility between the experimental and predicted values of Aflatoxins.

Probiotics are live microorganisms which when consumed in adequate amounts, can have a beneficial effect on the host. Lactic acid bacteria are the most common type that have been introduced as probiotics and are present in dairy products. The aim of this study was to isolate and identify the probiotics from microbial flora of cow milk and its traditional yogurt in Khoi area. To achieve this goal, the lactic acid bacteria were isolated by phenotypic methods (cellular morphology, colony pigmentation, Gram staining, catalase test, biochemical tests including growth in different temperatures 10oC, 15oC and 45oC, various concentrations 4% and 6.5% of salts and fermentation of 17 types of sugar) and their probiotic potential (resistant to stomach acid and bile salts) were evaluated. Then, to identify more accurately, the 16S rRNA gene of Lactobacilli were replicated with pairs of specific primers and then the purified PCR product was sent for gene sequencing. At the end, 14 strains of Lactobacilli were reported as the natural microbial flora with probiotic potential in Khoi area. These bacteria provide the good quality of the dairy products in those areas and can be used as the starter culture in industrial manufacture of dairy products.

This work was aimed to investigate the potential preparation of an biodegradable film preparation from bitter vetch seed protein and determine some of its physicochemical properties. The film was cast from bitter vetch protein concentrate (BPC) (5 g/ 100 ml alkaline water) and glycerol (50% w/w of BPC). The moisture content (MC), color, tensile strength (TS), elongation to break (EB), water vapor permeability (WVP) and surface hydrophobicity of the film were measured. The film with MC of 27.69%, TS 5.04 MPa and WVP 0.72 (gmm/KPa.h.m2) ws comparable with other protein films but its red and yellow indices in color (a=22.41 and b=37.20) and EB were higher than other protein based-films. Its surface hydrophobicity (49.83o) was higher than that of soy and sodium caseinate protein films and lower than red bean protein film. In general, according to the results, it seems that the film obtained from BPC has a good potential to be used in packaging applications.

Raisin is a principal traditional export product of Iran and has occupied a special position in the foreign trade of the country. During storage period, the product turns sticky and hard due to exudates syrup and moisture loss. To overcome this problem the application of edible coating suggests being of proper assistance. Edible coating may enhance the boundary layer resistance resulting enhanced shelf life of product. In this research the method of Accelerated Shelf Life Testing (ASLT) used for evaluation of storage and sensory properties (texture, color, taste and overall acceptability) of raisin. Raisin was treated with coating materials based on lipid (glyceryl monoestearate and carnauba wax) with 150 ppm essential oil of thyme (thymus vulgaris) and stored at 20, 35 and 50oC for 12 weeks. During this period of storage sensory properties were evaluated and estimate the modeling shelf life of raisin. Results showed that coating, affect on texture and color significantly and caused increasing shelf life of raisin. Temperature and storage time also showed significant effects on total sensory attributes. Maximum shelf life (394 days) determined at 20oC for carnauba wax coating with essential oil of thyme based on overall acceptability and linear regression and second order function had best fit with R2≤0.94 for all of treatments.

Dietary fiber is one of the important components in diet which possesses positive effects on health, in addition to having appropriate functional properties. Among plant sources, date seed is an abundant and inexpensive as well as rich source of dietary fiber. In this research, date seed was first fractionated into two parts including outer part (crust) and inner part (core) and then both parts were defatted. The two kinds of powders obtained from defatting crust and core were named crust fiber and core fiber. Chemical analysis showed that the amount of protein, insoluble dietary fiber and total dietary fiber in core were significantly higher than crust. Fat of crust was significantly higher than core. Also it was understood that the amount of total dietary fiber in both crust and core parts was high (70.68% and 74.17%, respectively). Water retention capacity and oil binding capacity of core fiber (2.80 and 1.29 gram/gram, respectively) were respectively higher and lower than crust fiber (2.66 and 1.40 gram/gram, respectively). Core fiber was lighter than crust fiber. The value of all the three parameters including water retention capacity, oil binding capacity and L* were acceptable in comparison with most of the agricultural by-products and commercial fibers.

The purpose of this study was to investigate the effect of lyophilized Alyssum homolocarpum seed gum-whey protein concentrate (with the ratio of 1:1, 1:3 and 3:1) on physicochemical properties of corn oil-in-water emulsions. Interfacial tension and emulsion characteristics such as particle size distribution, zeta potential, flow behavior, viscosity and creaming were investigated. The results showed that with the increasing gum ratio in the mixture, the interfacial tension increased, but the difference was not statistically significant. In emulsions stabilized with gum-protein mixture, increasing gum content, increased the particles size, negative charge on droplets surface, consistency coefficient, yield stress and hysteresis between the forward and the backward diagrams. The particle size distribution curve was monomodal and emulsions stabilized with this mixture showed non- newtonian and psedoplastic behavior. No creaming was observed in all emulsions.

The present study deals with modeling the effects of bentonite (1.5-5 g/lit) and gelatin concentrations (0.02-0.08 g/lit) along with time (30-80 min) at constant temperature and pH on color, turbidity, adjusted purity, ash and invert sugar content of purified raw sugar-beet juice through face-centered central composite design of response surface methodology and to optimize these key parameters of the process.  Our main goal was focused around the possibility to produce invert sugar directly from raw sugar-beet juice in conjunction with an alternate purification process in comparison with the conventional lime process used industrially. In this connection, second-order polynomial models were developed for dependent responses using least-square fit of regression analysis. The correlation coefficients of the developed response surface models were determined to be 0.90, 0.84, 0.90, 0.92, and 0.99 respectively for color, turbidity, ash content, adjusted purity, and invert sugar value of purified juice. The results of analysis of variance (ANOVA) revealed that all three independent parameters investigated have significant influence on raw beet-juice purity indexes. The optimum conditions were based on minimization of color, turbidity and ash content and maximization of invert sugar and adjusted purity at a constant temperature (75oC) and pH (4.5) and it was found to be at bentonite concentration of 1.55g/lit, gelatin concentration of 0/04g/lit and reaction time of 68.6 min. At this optimum point, color, turbidity, ash, adjusted purity and invert sugar content were found to be 1973 ICU420, 1.06 NTU, 0.54%, 91.4%, and 1.95%, respectively.

In this research, the production of low fat butter, as a novel product, based on full-fat soy flour and sodium caseinate was studied. Water: butter ratio, soy flour: sodium caseinate ratio and emulsifier content were the designed factors and their effects on rheological properties of low-fat butter such as hardness, spreadability, adhesiveness, elasticity and consistency were evaluated. The Central Composite Design (CCD) and Response Surface Methodology (RSM) were employed as experimental design and statistical analysis. By increasing water to butter ratio, as a principal factor affecting on product characteristics, hardness, adhesiveness, elasticity, consistency and spreadability were reduced. The final product was w/o emulsion which was low-calorie, had functional and nutritional effects due to protein components and also its properties could be compared with ordinary butter. Based on final results, the optimum formulation for low-fat butter were: water: butter ratio as 1.03 (50% water and 48.5% butter), soy flour: sodium caseinate as 1.57 (5% soy flour and 3.2% sodium caseinate) and 0.66% emulsifier.

The effect of apple and wheat fibers was studied on viability of Lactobacillus acidophilus in symbiotic yogurt and its physicochemical, sensory and rheological properties during 29 days storage at 5±1oC. The results of analysis showed that the number of Lactobacillus acidophilus in control and sample containing 0.5% fiber were reduced by 1 and 0.5 log cycle respectively and reached to 6 and 6.85 log cycle respectively at the end of storage period. But the sample containing 1% of fiber showed 0.25 log cycle increase in the number of Lactobacillus acidophilus at the same time and reached to 7.6 log cycle. This increase was higher in samples containing wheat fiber in comparison with those containing apple fiber (p<0.05). The samples containing fiber showed higher viscosity and lower syneresis in comparison with those not containing any fiber. The effect of wheat fiber on viscosity was higher than the effect of apple fiber (p<0.05). Increasing the amount of both fibers also caused samples to gain lower score for their color and taste. This decrease was obvious in samples containing apple fiber. Totally the samples containing 0.5% wheat fiber where known as best color and taste point of view between samples containing fiber. So it was concluded that using wheat fiber at the rate of 0.5% not only improved texture and chemical properties of yogurt but it could also provide the consumer satisfaction.

In the present study variation of air relative humidity at the inlet and outlet of a cabinet dryer as well as drying kinetic of pear fruit in thin layer were studied. The experiments were conducted at three temperature levels of 40, 50 and 60oC and three air velocity levels of 0.5, 1 and 1.5 m/s.It was observed that the difference between input and output air relative humidity increased when drying temperature was increased. This difference followed declining trend at the same level of drying temperature when air velocity was increased. If drying at lower air temperature and higher velocity is desired, for optimum use of energy, a closed loop drying method is appropriate. Otherwise, increasing in air temperature and decreasing in air velocity is recommended. Eight mathematical models were fitted on drying data and the best one was selected according to coefficient of determination (R2) and Chi-square (χ2) statistics for 70 percent of data. The model then validated by statistics of root mean square of error (RMSE), mean bias of error (MBE) and mean relative error (ARE) for 30 percent of remaining data. The approximation of diffusion model with highest R2 (0.998), and lowest χ2 (0.0001), RMSE (0.01), MBE (0.0008) and ARE (5.2%) was found an appropriate model for estimating the kinetics of thin layer drying of pear cubes drying in a cabinet dryer.

Flaxseed is one of the oilseeds that use as ingredient in food product due to its considerable nutritional and beneficial health effects. In this study in order to produce functional Taftoon bread, ground flaxseed was incubated at 30ºc and microwaved for 2.5 minutes in order to reduce cyanogenic glycosides compound. Wheat flour replaced with treated ground flaxseed at 5, 15 and 25 percent levels. Results showed that cyanogenic compound reduced 84.6%. Result of rheological properties test of dough showed that, with replacing wheat flour with ground flaxseed, water absorption of dough and expansion of dough during fermentation decreased and stability time of dough increased and the difference between them was significant (p<0.01). Results of stress relaxation test showed that addition of ground flaxseed to wheat flour, increases the viscoelasticity of dough. Results of oxidative stability test showed that with replacing wheat flour with ground flaxseed, peroxide and thiobarbituric acid value increased and highest value was at 15% ground flaxseed and had significant difference (p<0.01). Results showed that bread containing flaxseed had darker color and softer texture and staling of bread containing flaxseed was lower. Results of organoleptic test showed that bread containing flaxseed had better flavor, aroma, texture and overall acceptability by panelist, although color of bread had less acceptance at 15% and 25% level of replacing ground flaxseeds.