فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال هفتم شماره 4 (زمستان 1397)

The present study aims at reducing the energy consumption in the cooking process by using a simple technical method, a thermal shield around the cooking pot. The research has conducted experimentally and the effect of the thermal shield on the thermal efficiency was investigated regarding the geometric parameters of the pot (diameter and height) and the amount of fluid in the pre and post-boiling stages. The results showed that the thermal shield has a positive effect on pre-boiling stage leading to an average amount of 20% energy savings independent of geometry and the amount of fluid. It was also shown that the effect of thermal shield in the boiling stage is a function of liquid height inside the container. Also, for a constant value of thermal energy, the effect of thermal shield increases with the container height without limitation. It was also shown that the effect of the thermal shield in boiling stage is a function of the height of liquid inside the container. Finally, an economic investigation for Iranian households showed that utilization of a thermal shield in cooking process will save energy consumption equivalent to 12.5 million barrels oil per year.

Celiac disease is a common autoimmune disorder which is triggered by receiving gluten. In this study, corn flour was used as gluten-free flour. Therefore, in order to simulate the properties of gluten, the use of enzymes with cross-linking ability such as microbial transglutaminase at levels of (0, 0.75 and 1.5%), with sodium caseinate at levels of (0, 3 and 6%) were used as a substitute for gluten and their effect on rheological properties of dough, physical and sensory properties of corn gluten-free bread was evaluated. The results indicated that with increasing angular frequency, both the storage and drop modules increased. The specific volume of breads produced from corn was obtained when the specific volume concentration of the transglutaminase enzyme and sodium caseinate were in the highest amount (1.460a±0.02). The addition of enzyme and sodium caseinate to the bread formulation reduced the baking loss in comparison to the sample without these materials. The addition of the microbial transglutaminase enzyme to 0.75% resulted in a significant decrease in porosity and then the porosity increased by increasing the enzyme concentration. The addition of 3% of sodium caseinate along with 0.75% of the microbial transglutaminase enzyme to gluten-free bread resulted in the highest bread stiffness. The final acceptance of the produced samples decreased by increasing the enzyme and protein, so that the samples lacking these two compounds obtained the highest final acceptance score. Finally, according to the results, it can be concluded that using 0.75% of the microbial transglutaminase enzyme and 3% of sodium caseinate can be helpful for the production of gluten-free corn bread.

In this research, the effect of modified atmosphere packaging on the quality and shelf life of strawberries was investigated. For packing strawberries 3 gas compositions (air, N275%+CO215%+O210% and N275%+CO210%+O215%), polyethylene lining in 3 thickness of 30, 50 and 90 mm and 2 storage temperatures 4±1 and 8±1 °C were used. The effect of treatments on weight loss, firmness, soluble solids, titratable acidity and pH in strawberries at 20 days after storage was studied in a completely randomized design with factorial experiment in 3 replications. Results showed that the effects of gas composition and temperature on all of the mentioned factors are significant (P≤0.01), but the effect of the thickness of the polyethylene (PE) lining is only significant on the percentage of weight loss, soluble solids and titratable acidity (P≤0.01). The quality and quantity characteristics of strawberries were maintained better at temperature of 4 °C due to reduced breathing, evaporation and transpiration. The polyethylene lining at thickness of 90 mm, maintained the qualitative and quantitative qualities of the product due to low permeability and maintaining the moisture around the product within the package. The first gas composition (N275%+CO215%+O210%) was more suitable for keeping the qualitative and quantitative characteristics of strawberries due to more CO2 and reduced respiration. As a result, strawberries packed in a 90 mm thick polyethylene lining and a gas mixture (N275%+CO210%+O215%) at 4 °C had the best quality and highest durability.

One of the procedures for the stabilizing of frying oil, in order to preserve the synthetic antioxidants, is adding oils containing antioxidant and high oxidative stability compounds. The objective of this research was the quality evaluation of three frying oils mixture (Sunflower, Ladan and Iran) due to the addition of purslane and corn seed oils and frying over 12 h at 170±2 °C for this reason, the mixed frying oil, containing corn and purslane seed oil in the proportion of (70:15:15 w/w) called mixture 1, mixed frying oil containing corn and purslane seed oil in the proportion of (75:15:10 w/w) called mixture 2, corn seed oil, purslane seed oil and mixture of three frying oils in terms of qualitative indexes (peroxide, p-anisidine, totox, total polar compounds, oxidative stability and conjugate-DNs), were evaluated. At first the antioxidant activity rate of purslane seed oil was assessed and the value of 52.9±0.19 percent was measured. The comparison of two types of frying oil mixtures indicated that the values of peroxide, p-anisidine, totox and conjugate-DNs, indicators of mixture 1 and 2 were (25.83 meq/kg, 80.63, 132.29 and 15.01 μmol/g) and (28.13 meq/kg, 85.73, 141.99 and 17.17 μmol/g) respectively which had significant difference with frying and other oils (P<0.05). The higher ratio of purslane oil in the frying oil, mixture 1, increased its oxidative stability in contrast to oil mixture 2 and purslane preserved it against early degradation at high temperature.

Nowadays, food adulteration is important to marketing and production. The purpose of this study was to classify different types of honey (Thyme, Chaste tree, Jujube, Coriander, Barberry, Acacia and Alfalfa) with different herbal origin based on color characteristics, salinity, electrical resistance and total dissolved solids (TDS). For classification of honey, principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) of chemometrics method, were used. The results showed the two principal components (PC1 and PC2) comprise 77.69% of the total variance, which indicates the distinction between different honeys based on physicochemical characteristics. It was also shown in the LDA method was able to classify different honeys with an accuracy of 75%. On the other hand, the method of CA in the distance of 85.58, honey was placed in 7 groups that contained thyme, coriander, acacia, barberry and jujube honey in separate groups and alfalfa honey and chaste tree honey were scattered among the groups.

The aroma of honey is one of the important parameters in honey grading and that is depended on several factors, such as geographical origin, climate, botanical and environmental conditions. The aim of this study was the development and evaluation of an electronic nose as a new, fast and nondestructive method for detecting adulteration in honey. In this research, the ability of electronic nose as a non-destructive system for detecting honey adulteration with different percentages (pure, 20% syrup, 40% syrup, 60% syrup and 80% syrup) was investigated. The developed electronic nose consists of 8 metal oxide semiconductor sensors (MOS) to detect adultery in honey. After preprocessing the data obtained from the electronic nose the chemometric methods were utilized to classify different type of honey. Principle component analysis (PCA), hierarchical cluster analysis (HCA), linear discriminate analysis (LDA), were used to analyze the data obtained from electronic nose. Based on the results, the detection of adulteration was 98.4% of variance for PCA method, 99% accuracy for HCA method and 100% classification power by LDA method.

The survival ability of probiotic bacteria in food products is one of the most important challenges ahead. The wild leek (Allium ampeloprasum) herb of the Allium family contains various prebiotic compounds that can stimulate the growth of probiotic bacteria. In this research, sensory properties of cheese based on Allium ampeloprasum as a medicinal plant and flavoring was evaluated. For this purpose, after chemical tests on raw milk, different cheese treatments were prepared to determine the effect of fresh and dry concentrations of 1 and 2% of plants, as well as non-herb control containing probiotic bacteria Lactobacillus acidophilus (PTCC 1643) on the growth of Lactobacillus acidophilus bacteria. The results showed that probiotic bacteria Lactobacillus acidophilus had decreasing trend in all treatments and control during storage, but in the treatments containing Allium ampeloprasum, this trend was less. At the end of the 45th day, the lowest bacterial count (Log CFU/g) was observed in the treatment without plant (6.69) and the highest in the sample containing one percent dry plant (8.12). The results of pH assessment also showed that in all samples, the process of pH reduction observed naturally with time of the cheese ripening. However, in treatments containing plant, there was significant difference between 30 and 45 days with non- plant control (P≤0.05). At the end of the 45th day, the lowest bacterial count (Log CFU/g) was observed in the treatment without plant (6.69) and the highest in the sample containing one percent dry plant (8.12). In sensory evaluation, samples containing 1% dry plant and probiotic bacteria had the highest score among different treatments and specified the addition of Allium ampeloprasum as a plant additive could increase the sensory properties of the product and could be successfully used to produce synbiotic cheese.

In this research, optimization of pumpkin (Cucurbita pepo) hydrolysis condition was investigated in order to achieve maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and nitric oxide inhibition activity using Design Expert software and response surface method. For this purpose, hydrolysis conditions including concentration of alcalase enzyme were selected within 0.7-3.30%, temperature 32-58 °C and hydrolysis time 30-290 min as independent variable. The results showed that optimum hydrolysis conditions to achieve the maximum DPPH radical scavenging and nitric oxide inhibition activity were temperature of 44 °C, hydrolysis time of 260 min, and enzyme to substrate concentration of 3% which under this condition the DPPH radical scavenging and nitric oxide inhibition activity of hydrolyzate was 72.03 and 89.34%, respectively that was largely similar to the results proposed by the software (75.33 and 84.71%). According to the results, pumpkin seed protein hydrolyzate showed high antioxidant and nitric oxide inhibitory properties and can be used as a suitable ingredient in food formulations.