فصلنامه پژوهش های صنایع غذایی
سال بیست و چهارم شماره 4 (زمستان 1393)

Barbari bread is one of the most widely used breads in Iran which has high loss. Consequently, finding a solution for quality improvement of this type of bread seems to be necessary. One way to achieve this goal is optimizing of flour enzymatic activity by using enzyme sources such as barley malt. The purpose of this research was to optimizing the percentage of barley malt flour in order to improve the quality of Barbari bread. To this purpose, barley malt flour was added to flour at concentrations of 0.5, 1, 2 and 4% based on flour weight and five bread samples including control sample (without barley malt) and four samples containing mentioned added amount of barley malt were prepared. In the next step, some experiments were fulfilled to measure the quality of bread samples. By adding barley malt flour up to 1% on flour weight, width/height ratio, oven spring, water absorption, dough development time and Farinograph quality number increased; whereas the falling number and crumb hardness of fresh bread was decreased with the increasing amount of barley malt. Microstructure of bread which were studied by SEM, showed that barley malt up to 1%, creating some type of fluidity in cell walls. Sensory evaluation showed that the quality of the sample containing 4% of barley malt flour was lower than the control sample because of its malty taste and sticky crumb. As a result of this research, the sample with 1% of barley malt flour was recognized as the best bread sample.

Ability of Candida rugosa for separation of two main conjugated linoleic acid (CLA) isomers including 9-cis،11-trans and 10-trans،12-cis was investigated in the mixture of free fattyacids of these isomers and L-menthol. In order to effectively separate two mentioned isomers، optimization of reaction conditions was conducted using response surface methodology (RSM). After data analysis by D-optimal design، the best reaction conditions for maximum esterification of 9-cis،11-trans isomer with L-menthol after just one step esterification were as follows: reaction time 23. 1 h، temperature 32. 6°C، enzyme amount 135. 4U، molar ratio of CLA oil to L-menthol at 1:1. 7 and pH at 7. 7. At this optimum point، the lowest amount of c9، t11-CLA isomer (6. 7%) was observed in free fatty acids fraction. This effective process for purification of CLA isomers using L-menthol could be applicable to produce food supplements.

Traditionally, pot (Kope) cheese produced from raw milk in the Northwestern provinces of country and nowadays some of the Kope cheese producers have been used of plastic or metal container as a pot. The aim of this study was to determine the effect of pasteurization and packaging on the physicochemical and sensory properties of Kope cheeses during 120 days of ripening. The results revealed that before filling of cheese in pot and plastic container, pasteurized cheeses had higher salt and pH, and pasteurization process increased acidity in pot cheese and pH in cheese which ripened in plastic container at 120th day of ripening. Although usage of pot as a container increased pH, total solid, salt, ash, fat, protein and also overall taste, where plastic container increased acidity and lipolysis of cheese.

In this work two essential oils, coriander (CO) and lemon (LO)at four levels (0.1- 0.4% v/v solution of film), were incorporated into Carboxymethyl cellulose (CMC) films using a solution casting method to improve the mechanical (tensile strength (TS), elongation at break (EB)) and water vapour permeability (WVP) properties. Also the effect of these films on pH and color of meat were investigated. Increasing the content of CO or LO from 0.1% to 0.4% increased EB values from 30 to 70% and they significantly (p<0.05) reduced TS value. The CMC incorporated with 0.4% of essence had significantly decreases WVP. The CMC Film containing 0.4% v/v of each essential oil was applied to the surface of lamb meat. The changes occurred in color parameters (L*, a* and b*) and pH of samples was determined during 8 days of storage at 4±1 ºC coating with CMC film, with or without essential oils, reduces pH of meat which the lowest pH was related to samples wrapped with CMC-LO film. All of the CMC-based films significantly (p<0.05) decrease L* and b* parameters of coated lamb meat as compared to uncoated samples. Incorporation of essential oil, especially LO, to the CMC matrix led to a reduction a* value. These results suggest that CO and LO have the potential to be directly incorporated into CMC, improving mechanical properties and WVP to prepare good biodegradable films for various food packaging applications, but using of this films in lamb meat had unfavorable effect on the color of meat.

In this study survival of Lactobacillus acidophilus (LAFTI-L10) and Bifidobacterium lactis (LAFTI-B94) and their effect on chemical, sensory and microstructure properties of Iranian Doogh were investigated during 60 days at 5±1°C. Three treatments including C (control, no probiotic), BL containing Bifidobacterium lactis and LA containing Lactobacillus acidophilus were prepared. The results showed that the number of Bifidobacterium lactis and lactobacillus acidophilus were decreased from 8.53 to 8.07 log CFU/g and from 8.4 to 7.45 log CFU/g respectively during storage. The pH of sample containing Lactobacillus acidophilus were lower than that in other samples and the acidity was significantly higher than the treatment containing Bifidobacterium lactis (P<0.05). The results of study on microstructure showed that Lactobacillus acidophilus caused more regular aggregates in casein micelles than Bifidobacterium lactis. According to the sensory evaluation, the treatments containing probiotic obtained highest score for flavor in comparison with control samples (P<0.05). Also the final numbers of probiotic bacteria were more than the recommended minimum number necessary for therapeutic effects on human health (106 - 107 CFU g-1) at the end of 60 days. So probiotics not only did not have adversely effect on physicochemical and sensory properties, but also improves the properties of Doogh. Therefore Doogh can be an effective carrier of probiotic organisms.

In this research Iranian locust bean gum (LBG) was extracted from carob seeds collected from Fars province and purified locust bean gum was produced using isopropanol. A commercial type locust bean gum was also used for comparison. Solutions of the three gums were prepared and using U-tube viscometry critical concentration, intrinsic viscosity and coil overlap parameters were determined. For Iranian LBG, Iranian purified LBG and commercial LBG, critical concentrations were 0.6, 0.25, and 0.15% (w/v) and intrinsic viscosities were 3.95, 9.05 and 9.48 (dL/g), respectively. Both Iranian and commercial LBGs were capable of viscosifying aqueous solutions, however the commercial LBG was stronger and able to produce viscous solutions at lower concentrations. The results showed that purification process increases the intrinsic viscosity and decreases critical concentration of Iranian LBG to a great extent. Coil overlap parameter was also measured for the three LBG samples.

Today regarding lack of essential fatty acids, antioxidants and fiber in the diet, there is a necessity to compensate these components by consumption of food products containing these substances. These substances have high nutritional value and have an important role in prevention from cardiovascular disease as well as some cancers. Among oil seeds, flaxseed is a rich source of α- linolenic acid and contains high amounts of tocopherols, fiber and lignans. Macaroni has high- consumption food product, therefore is appropriate for enrichment. In this study, flaxsnseed at concentrations of 0 (control sample), 5, 10 and 15% was incorporated as powder into macaroni formulation. After 3 months of storage, qualitative properties were measured and compared to control sample. These properties included: oil percent, acidic value, peroxide value, essential fatty acids, fiber amount and tocopherol. Macaroni samples containing flaxseed powder had higher oil, linolenic acid and tocopherol content than control sample. An increase in the percent of flaxseed led to decrease in moisture content of the samples and total solids in baking water. Addition of flaxseed increased protein content, baking weight, acidity and peroxide value of samples. At all, it can be concluded that by addition of flaxseed powder to the macaroni formulation, it is possible to introduce a new product with high content of essential fatty acids and antioxidant compounds to the market.

Bene butter is a paste form product that contains mainly milled, roasted bene kernel with sugar. This product has suitable nutritional properties and knowing about its rheological characteristics can be useful for industries. In this investigation, time-dependent flow properties of pistachio butter were determined using three different models such as Weltman, first-order shear stress decay with zero equilibrium stress value and first-order shear stress decay with a non-zero equilibrium stress value. For this reason for evaluating the correlation between shear stress and time of shearing in a constant rate (150 s-1), samples at two different temperatures (25°C and 45°C) were evaluated for 10 min. Shear stress vs. time of shearing data were then assessed using the three models. R2, RMSEand %E were applied to choose the best modeland among these models the Weltman model was the best fitted to experimental data. It was found that pistachio butter exhibits a thixotropic behavior and its apparent viscosity decreases with increasing the time of shearing.

Nowadays using the hedonic pricing model has many applications in various industries for identification of the actual preferences of consumers. There are problems in the dairy industry of country such as low production levels, export, import and consumption per capita is also low. With checking the hedonic pricing of major dairy products such as milk, yogurt and cheese that makes it possible to identify consumer preferences about different factors in these products, the importance of each of their properties can be specified. This is a great help to manufacturers to produce the products in order the consumer preferences and spread the economic activities in the region and also increases the consumption of these products that consume them is inevitable. Then with Laboratory Information, The hedonic pricing function for milk, yoghurt and cheese was estimated. Estimating hedonic pricing Function for this products suggests that in the qualitative Specifications of cheese, fat, salt, dry matter, protein and type of packaging has the highest values, Also, fat, dry matter, type of packaging and flavor are the main characteristics that affect the hedonic price of yogurt And it was found that the hedonic price of milk is influenced with Fat, dry matter, acidity, color and flavor.

In this study, enriched emulsion of Artemia was made with reverse engineering using waste materials and by products of aquatic animals harvest (scomberidae, squids wastes) and olive oil extraction factories. Suspensions were tested and enriched Nauplii then were analyzed by GC. The enrichment percentage of Nauplii in evidence and homemade samples were achieved as 27.47±2 and 22.14±2 %, respectively. Enriched live Artemia nauplii were biometrically measured containing 500 newly feeding larvae for 30 day of Oncorhynchus mykiss consisted of 4 treatments in three replicates including: 1)factory concentrated, 2)Artemia nauplii concentrated, 3)Artemia nauplii concentrated enriched by imported super selco and 4)Artemia nauplii concentrated enriched with Super Selco produced by reverse engineering. The results revealed that treatments 1 and 2 had a significant difference with treatment 3 and 4 on survival rate, growth coefficient and mortality rate. Final results showed that there is the potential of Super Selco enrichment oils production similar to foreign samples by interior potential.

Increasing the pasteurizing temperature of contaminated milk in classic method for completing the heating process causes burning the milk layer on pasteurizer and creates thick milk stone. This event in addition to prevents the sufficient transfer of heat, produces carcinogenic compounds, changes in milk color and increases remained microbial load in the milk, therefore threaten the product's health. In the method used in this study (induction heating), electromagnetic current was induced into milk and caused be heated faster than classic method. In this research, milk was pasteurized by using an induction heater in 243 different conditions and optimized method was selected for adequate process via a factorial experiment design. In this experiment, the effects of four different factors including: 1) 3 intensities of electricity transmittance (350, 1000 and 1600 watts), 3 levels of test containers surface (12, 17 and 23 cm), 3 temperatures (72, 75 and 84 °C) and 3 pasteurization time (15, 20 and 30 seconds) were used in three replications. The optimized method was selected respectively in three steps based on 1) the minimum percentage of microbial load, 2) a minimum elapsed time for milk pasteurization and 3) the lowest energy consumption for processing. Consequently, the results showed that the destruction of total bacterial load was 99.5 % in selected induced heating method in comparison to classic method (98.23%). Moreover, Coliform and Escherechia counts in induced heating method have been one tenth to classic method. In induced heating method, milk stone wasn’t produced due to the fast heating transfer.

Low quality and shorter shelf life of the bread in our country is a major issue leading to bread wastage. The aim of the present study was to spary dry sourdoughs containing three Lactobacili species and to investigate the effect of addition of different percentages of dehydrated sourdoughs to flour quality and rheological properties of dough. Fresh sourdough containing lactobacillus plantarum, corwatus and paralimentarius (isolated from sourdough of traditional breads) was first prepared followed by dehydrating through spray drying. Finally, dried sourdough containing three Lactobacillus species at concentrations of 3, 6, 9 and 15 % (w/w) were added to the flour. Rheological properties were then investigated by Farinograph and Extensograph tests. Also pH and titratable acidity of obtained flours were measured. In this research a fully randomized block design followed by mean comparison using Duncan’s multiple range at probability level of = 95%. Results showed that addition of sourdough containing three kinds of starters decreased pH and increased titatable acidity. Regarding Farinograph results such water absorption and dough development time were increased with sourdough addition. However dough stability time was decreased. Ultimately in order to prepare molded bread containing dried sourdough which can retain its desirable rheological properties, wheat flour containing 15% of L.corwatus is recommended.