فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال نهم شماره 3 (پاییز 1399)

Kichi is a local sweet bread that is cooked in the west of Iran, especially in Chaharmahal and Bakhtiari Province. This product is traditionally produced and has a low shelf life and hard texture. Therefore, the aim of this study was to investigate the effect of xanthan gum (0, 0.1, 0.3 and 0.5%) to improve the quality of Kichi sweet bread. Also mean size area, porosity, fractal dimension, and color parameters of Kichi bread were evaluated. The results showed that addition of xanthan led to improving WHC. The results of the texture analysis showed that softer samples were obtained in the low concentrations of xanthan gum (0.1% based on flour) and gumminess in this sample was significantly less than other samples (p < /em><0.050). Also, the porosity of the product in the low concentrations of xanthan (0.1%) was similar to the control, but in the high concentration of xanthan gum, the porosity of the product reduced. On the other hand, the results showed that the addition of xanthan gum did not affect the fractal dimension of the product texture. In the case of product color, the xanthan had a significant effect on the L* and b* values of the texture. Finally, it can be stated that using 0.1% of xanthan gum in the formulation of this local bread led to the production of a quality product regarding color and texture. The sensory evaluation results of the samples showed that the addition of xanthan improves the sensory properties of the samples. In general, samples containing 0.1% xanthan had better texture and sensory properties.

Monascus purpureus can produce a wide range of natural pigments so attract the attention of food producers as substitute of synthetic colors. Monascus pigments usually accompanied with citrinin contamination which limits their wide application in foods. The usage of Saccharomyces cerevisiae is known as a useful biological way for citrinin elimination. In this study, the effect of  Saccharomyces cerevisiae cells in twomodes of treatment (heat treatment at 121  °C and acid treatment in 2M HCL) and live at three different concentrations (103, 104, 105 CFU/mL) were investigated on the amount of citrinin and yellow, orange and red pigments produced by Monascus purpureus. The results showed that live yeast cell and yeast cells treated by heat and acid significantly decreased the citrinin in culture, so that citrinin content decreased from 4.43 mg/L in control sample to 0.9, 0.10 and 0.07 mg/L (at 105 CFU/mL yeast suspension) respectively. The maximum amount of yellow, orange and red extracellular and intracellular measured pigments belong to the samples with live yeast, while the amount of this pigments in the samples containing yeast treated with heat and acid reduced respectively. Among the treatments, the use of live yeast at concentration of 104 CFU/mL per milliliter provided the best conditions to achieve the desired goal.

According to the multiple role of fat in food products, it is necessary to use a substance as a substitute of fat to maintain the rheological, texture and sensory characteristics of low-fat products. In this study, oleogel system was applied to produce low-fat product. Pickering emulsion-templated was applied to produce oleogels. Isolated soy protein (ISP) and basil seed gum (ISP-BSG) were used for the preparation of Pickering. ISP-BSG particles were prepared with different mass ratios of ISP-BSG, 1:0, 1:1, 2:1 and 3:1 and named 1S:0B, 1S:1B, 2S:1B and 3S:1B, respectively. The type and structure of the Pickering used affected the amount of oil retention in the oleogel (p < /em><0.05). The presence of basil seed gum in a suitable ratio with protein (2S:1B) caused a more stable oleogel, higher mechanical strength, and more compact network. Finally, the oleogels were prepared with better oil bonding capacity. The highest and lowest thermal stability rates were for the 2S:1B and 1S:1B samples, respectively. The highest and lowest consistency levels were observed in 2S:1B and 1S: 0B samples, respectively (p < /em><0.05). Investigation of the viscoelastic properties confirmed the gel formation in the oleogel system. According to the stability and textural properties of oleogel samples, two formulas 1S:0B and 2S:1B were used to produce cream with reduced fat (5, 10 and 15%). The highest overall acceptance was obtained in the 2S:1B sample with a 5% reduction in fat, which had no significant difference with control cream.

In this study, the formulation of fresh low-fat yogurt containing Balangu seed gum was modeled and optimized. In this study, first the independent variables of balangu seed gum (0 to 0.1%) and fat (0 to 2%) were modeled completely randomly in the form of a central composite design and each of the response variables (syneresis, pH, flavor, color, texture, and overall acceptance) were presented in the form of a polynomial regression model as a function of independent variables.The results showed that with increasing balangu seed gum, syneresis and pH of the samples decreased and the flavor, color, texture, and overall acceptance of the samples increased. Also, the increase in fat only decreased the syneresis of the samples. Then, the obtained models were optimized by multi objective particle swarming algorithm and numerical optimization algorithm in response surface methodology, so that minimum syneresis and maximum texture, flavor, color and general acceptance scores were obtained. The results of comparing the mean of three optimal points of the two algorithms showed that in general, in optimizing the formulation of low-fat yogurt containing balangu seed gum, the multi-objective particle swarming algorithm has a better performance than the numerical optimization algorithm in response surface method. The average optimal amount of balangu seed gum and fat in the multi-objective particle swarm algorithm was 0.85 and 1%, respectively, and in the method of optimization algorithm in response surface methodology, was 0.89 and 1.94%.

In the current study, the nanofiber gel of tomato pomace was prepared using a super disk grinder device available at Nano Novin Polymer Co., Iran. Three different concentrations (2, 4 and 6%) of the gel prepared and rheological tests including amplitude sweep, frequency sweep, temperature sweep, and flow behavior were done. DLS results showed that the average diameter of tomato nano-gel was around 38 nm. The power law model was chosen as the best model for describing flow behavior data. All samples showed a shear-thinning behavior that viscosity decreased with increasing shear rate. A hysteresis loop was observed in all samples which confirmed the thixotropic characteristic of gels. Based on amplitude sweep data, elastic modulus (G') was higher than viscous modulus (G"), in addition, crossover points of all gels showed that the flowability decreased with increasing concentrations. Based on frequency data, G' in all concentrations was higher than G" and both parameters increased with increasing concentration from 2 to 6%. In lower frequencies, all gels showed solid-like behavior while G' and G" increased with increasing frequency indicating the weakening of the gel network. G' and G" gradually decreased with increasing temperature from 5 to 50 ºC which confirmed that all gels were weakened at high temperatures, but in the cooling cycle, all gels recovered their structures and no remarkable hysteresis was observed.

In this study, the effects of the coating by chitosan (Cs) and its oligosaccharides (CsO) on some quality properties of peeled vannamei shrimp (Litopenaeus vannamei) during 3 months of frozen storage were compared with sodium pyrophosphate (SPP) (1 and 2%), Cs-SPP (1 and 2%) and CsO-SPP (1 and 2%). The moisture content, conjugated dienes (CD), thiobarbituric acid (TBA), color and texture properties of the samples were analyzed. The results showed that coating of shrimp by chitosan and its oligosaccharides, alone or in combination with SPP showed significant effects on the texture characteristics (springiness and chewiness) compared with the control and SPP-treated batches (P<0.05). The CD and TBA indices showed an increasing trend during storage (P<0.05). In the immersed treatments at CS 1% and in combination treatment with SPP, the TBA value was increased of 0.28 to 0.58 and 0.82 mg malondialdehyde/kg. This index was increased in the control and SPP (1 and 2%) to the 0.92 to 0.97 mg malondialdehyde/kg. According to the results, the treatments coated by chitosan and its oligosaccharide alone or in combination with sodium pyrophosphate had an effective role in inhibiting lipid oxidation and preventing its undesirable effects on frozen shrimp. In addition, color parameters (L*, a*, b*) in the treated samples by chitosan showed positive effects on stabilizing and improving the color of frozen shrimp during storage. Overall, the coating by chitosan and its oligosaccharides could maintain the quality of peeled frozen shrimp.

Nowadays due to the role of nutrition in public health, as well as the use of probiotic bacteria that exposed to acute conditions of food processes and the gastrointestinal tract, is always one of the concerns of researchers in food and pharmaceutical sciences. Therefore, probiotics has been proven as a new technique for the tolerability of food samples coated with biopolymers in beneficial emulsions under gastric and intestinal simulation conditions. In this study, three formulations were prepared for microcoating suspension (a combination of whey protein concentrate, inulin and Persian gum in the range of 14 to 14.3 g per 100 mL). The results showed that microcoating efficiency, resistance to acid and alkali stress and viscosity evaluation, microscopic properties and finally the release rate synthesis, the second formulation (8.5, 5.5 and 0.2 g for whey protein concentrate, inulin and Persian gum, respectively) was considered as a suitable matrix, in the following, the durability characteristics during two months were evaluated at two temperature levels of 25 and 40 °C. The effect of shelf life caused a decrease in the population of Lactobacillus plantarum at two temperatures, which was much more severe at a temperature of 40 °C than the ambient temperature. The results of capsule microparticle images obtained by scanning electron microscopy showed that the surface of properties and the effect of wall compositions on the microstructures of the particles at two different temperatures were different. According to the results, the temperature of 40 °C had a much higher surface shrinkage compared to the small particles of the capsule stored at room temperature.

In this study, the sterols of 5 different vegetable oils (olive, canola, corn, sesame as well as sunflower) and an animal oil (lard) were analyzed by liquid-liquid extraction and gas chromatography. The sterols in real samples were identified by mass spectrometry. Calibration curves were plotted with the correlation coefficients more than 0.99 for each sterol. The detection limits for b-sitosterol, campesterol, and cholesterol were 0.48, 2.38, and 0.44 mg L-1, respectively. The recoveries were obtained in the range of 95-109%, and their relative standard deviations were less than 9% in a day and between three days. The concentration of each sterol in real samples was determined using the purposed method. To detect lard adulteration in vegetable oils, mixtures of extra virgin olive oil and lard in four different ratios were prepared and analyzed. According to the results, at a higher percentage of lard in extra virgin olive oil, cholesterol increased and plant sterols were decreased. The curve plotted via the cholesterol concentration versus the added amount of lard, was linear with the correlation coefficient of more than 0.99. Moreover, this method made the detection of lard adulteration possible in olive oil with 1% detection limit and less than 3% uncertainty. Therefore, the identification of lard adulteration in plant oils (cholestrol-free) can be based on the suggested method.