Asefeh Latifi; Mohsen Esmaiili
Abstract
Introduction: More than half of the world's people consume rice. Rice consumers, especially in Asia know that cooking properties of rice change with its storage. This phenomenon is called aging. The increase in hardness, decrease in adhesiveness during cooking and decrease in solid loss, are the major ...
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Introduction: More than half of the world's people consume rice. Rice consumers, especially in Asia know that cooking properties of rice change with its storage. This phenomenon is called aging. The increase in hardness, decrease in adhesiveness during cooking and decrease in solid loss, are the major changes in rice which caused by aging. However, while some consumers prefer new rice like Japanese (Zhou, 2002) Iranian and many other consumers prefer aged rice. The change in physicochemical properties of aged rice is caused by the alteration and interaction in lipid, protein and starch (Juliano, 1985; Sodhi, et al. 2003; Teo et al. 2000). The conventional aging of rice takes 3-6 months (Jaisut et al. 2009; Soponronnarit et al. 2008).Yet this method needs more space for storage leading to high operating costs. It is necessary to examine other methods that can reduce the aging time and maintain the rice properties similar to those obtained by the conventional aging process. The process for accelerated aging could be developed either by dry or wet heat (Rayaguru et al. 2011; Rosniyana et al. 2004). The dry heat method was successfully tested with heating of rice in high temperatures in a closed container (Battacharya, 2013). One of the basic problems that occur during dry heating is that any moisture loss leads to cracking. Although the concept is simple in theory, it is complicated in practice. Another drying process for accelerated aging of rice employs a fluidized bed dryer. However, this may decrease head rice yield (Soponronnarit et al. 2008; Wiset et al. 2005), not to mention the fact that these dryers are rare and expensive in rice producing countries. Hence, wet heat is more practical and economical in the mentioned countries. The environmental optimum conditions for accelerated aging of Basmati paddy, at temperature 30–50 °C, relative humidity 50–90% and aging period 3–14 days, has been studied and reported to be 43 °C, 71.0% relative humidity (RH) and 11 days (Rayaguru et al., 2011). Parboiling has been implemented as a method of improving the quality of rice. Nonetheless, it is a lengthy process involving soaking, steaming and drying, which results in the complete gelatinization of starch (Gujral, and Kumar, 2003). According to the importance of accelerated aging, the aim of this study was to evaluate quality attributes and physicochemical properties improvement of Tarom variety of paddy.
Materials and methods: In this study, Tarom variety of paddy (a local variety, with high-quality and large area cultivation in Mazandaran province) was chosen. For accelerated aging, two methods were done: Steaming (or steam curing) and controlling the environmental conditions. In steaming method, the paddy was divided into two portions. The first which had an initial moisture content of 24% (wet base) and the second was the paddy which had been rested at the ambient temperature allowing its moisture content to reach 17%. To accelerate aging of the paddy in two moisture levels i.e. 24 and 17%, the samples were treated by steaming (or steam curing) for 5, 10 and 20 min, and then both of samples were dried with fixed bed dryer at 40 ◦C until the grain moisture content reached 11%. Afterwards, the paddy samples were dehusked and polished with satake miller apparatus. Milled whole rice kernels were separated from broken rice for evaluation of physicochemical properties. In controlling the environmental conditions, the samples were dried with fixed bed dryer at 40 ◦C until the moisture content reached 12%, and then stored at 43 °C and RH=74% for 11 days. Similarly, to produce white rice, the paddy samples were dehusked and polished as mentioned above. The control sample which had an initial moisture content of 24% (wet base) was only dried at 40 ◦C to moisture contend wet basis 11%. Several parameters including head rice yield (the percentage of the mass of white rice that remained as head rice after milling), hardness of raw kernel (the maximum force for breakage of raw white rice), color (b value), chalkiness (weight of the kernel that had chalkiness over one half of the kernel surface in 5 gram of white rice), aroma (using hedonic test), pasting properties (including the peak viscosity, final viscosity, breakdown viscosity and setback viscosity), texture profile analysis (TPA) and thermal properties of rice (the onset temperature, peak temperature, conclusion temperature and enthalpy of gelatinization) were determined. The resultant data were subjected to the analysis of variance using SPSS (ver. 19) software. Duncan’s test was used to establish the differences between mean values at 95% confidence interval.
Results and discussions: The quality attributes of the produced white rice were compared with that of the control samples. By doing the steam curing treatment, solid loss of the rice decreased, adhesiveness decreased, gelatinization temperature increased and viscosity changed. All of the mentioned changes were similar to the alterations that occur in naturally aged rice. By controlling the environmental conditions, the solid loss decreased and the elongation increased. According to sensory and apparent characteristics including aroma and chalkiness, treatment by controlling the environmental conditions could be recommended. Steaming treatment for the three levels of time led to complete loss of aroma.
Forough Mohtarami; Mohsen Esmaiili; Mohammad Alizadeh khaled abad; Seyed Mahdi Seyedain Ardebili
Abstract
Introduction: A mixture of wheat flour, water, salt, yeast and other optional ingredients such as preservatives, enzymes, whey powder, surfactants, sugar, fibres and improvers form bread dough. Enrichment of dough and bakery products by dietary fibres such as wheat bran and resistant starch, beta-glucans ...
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Introduction: A mixture of wheat flour, water, salt, yeast and other optional ingredients such as preservatives, enzymes, whey powder, surfactants, sugar, fibres and improvers form bread dough. Enrichment of dough and bakery products by dietary fibres such as wheat bran and resistant starch, beta-glucans and inulin has been reported (Peressini, & Sensidoni, 2009; Hager, Ryan, Schwab, Gänzle, O’Doherty, &Arendt, 2011; Wang, Rosell, Barber, 2002; Angioloni, Collar, 2008). Whey has many applications in food and dairy industries due to its high quality of nutrients and functional properties. It possesses essential amino acids (Mann, 1998; Sharma, & Bhatia, 1999). There are other alternatives such as transglutaminase and asparaginase enzymes as innovative ingredients, which are recognized as safe in the food technology. The microbial transglutaminase enzyme (MTG) catalyzes the reaction between a ε-amino group of lysine residues and a β-carboxyamide group of glutamine residues, which causes to make covalent cross-linking of proteins (Yokoyama, Nio, & Kikuchi, 2004). Asparaginase (ASP) can catalyze the hydrolysis of asparagines, as a key factor for acrylamide formation, into aspartic acid and ammonia (Ciesarova, Kukurova, &Benesova, 2010). The present work was undertaken to study the influence of whey powder, inulin, asparaginase and transglutaminase enzymes on farinograph and extensograph properties of wheat flour dough using a D-optimal design.Materials and methods: Two types of wheat as insect damaged (50% insected) and sound hard red wheat (imported variety), milled into two types of flour by traditional mill. The characteristics of the flours such as moisture, ash, protein, falling number, wet gluten and Zeleny-value were determined using AACC methods (2000) in three replicates. Enzymes included MTG and ASP and other applied additives such as inulin (Frutafit-HD) and whey powder used at different levels based on flour weight in dough formulation. Effect of enzymes, additives and wheat flour types (WFT) on farinograph and extensograph characteristics were conducted according to the constant flour weight procedure of AACC (2000). D-optimal design was used to determine the effects of five independent variables including MTG, ASP, whey powder, inulin, and flour type on farinograph and extensograph properties. Response data were used to fit the second-order polynomial equation. Normal probability was used for separation of significant effects from noise or random effects. The significance of each coefficient in the regression model was determined using p-value lower than 0.05. Adequacy of models for regression were estimated using coefficient of determination (R2) and adjust R2 (adj-R2).Results and discussion: According to chemical and physical analysis of flour, it is obvious that in spite of having nearly the same amount of protein and wet gluten, the two types of flour had prominent difference in dough and gluten quality as indicated by gluten index and farino-extensograph tests. Due to this fact, the wheat flours with gluten index of 5.43±4.31 and 76.93±5.87 were named as weak and strong flours, respectively. Analytical data of farinograph properties were fitted to regression models. Analysis of variance of lack-of-fit test showed that the water absorption model is adequate with a non-significant lack of fit (p=0.267) and a satisfactory adj-R2 (97.53%). Among the different additives, strong wheat flour had positive effect and inulin and whey powder had negative effect on water absorption. According to half-normal plot and regression model coefficients, wheat flour type, inulin and whey powder significantly affected dough development time (DT) and stability (S). The models of DT and S had R2 values of 88.58%, 98.45% and non-significant lack of fits p=0.087 and p=0.018, respectively. DT and S increased with an increase in inulin and whey powder level using strong wheat flour. The regression model for degree of softening as a function of different ingredients was significant at a p-value less than 0.0001. Based on analysis of variance, the model appeared to be adequate with a non-significant lack of fit p=0.017 and a R2 value of 97.57%. Among the investigated factors, wheat flour showed the greatest positive effect on the degree of softening followed by inulin. The degree of softening was decreased by addition of inulin and whey powder. Among the interaction terms, a negative interaction effect on degree of softening was found between MTG and ASP (p
Nina Daliri; Fariba Zeynali; Mohsen Esmaiili
Abstract
In this research the effect of oil type, process time ,temperature and pre-treating methods on moisture content, oil uptake, acidity and peroxide values of Zucchini slices (Cucurbita pepo. L) during deep fat frying process were investigated. The samples were pretreated by blanching (97 ºC for 5 ...
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In this research the effect of oil type, process time ,temperature and pre-treating methods on moisture content, oil uptake, acidity and peroxide values of Zucchini slices (Cucurbita pepo. L) during deep fat frying process were investigated. The samples were pretreated by blanching (97 ºC for 5 min) and microwave (900 W for 2min) methods before frying process. Frying experiments were carried out at two temperatures of 130 and 170 ºC for 7 and 4 minutes respectively by using two types of oil i.e. sunflower and special frying oils. The results showed that moisture content, oil uptake, acidity and peroxide values were significantly affected by temperatures, pretreatments and oil type (p
Mohsen Esmaiili; Ali Hassanzadeh
Abstract
The sorption isotherm and state diagram of sundried, golden and sultana raisins were constructed for investigation and comparison of the product stability. The isotherms were measured at 15, 25 and 35 °C using an isopiestic method and the data were modeled with GAB model. Glass transition temperatures ...
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The sorption isotherm and state diagram of sundried, golden and sultana raisins were constructed for investigation and comparison of the product stability. The isotherms were measured at 15, 25 and 35 °C using an isopiestic method and the data were modeled with GAB model. Glass transition temperatures of the products were measured by differential scanning calorimetery (DSC) and fitted to Gordon Taylor model. Moisture sorption results indicated that the amount of moisture adsorption and the GAB monolayer moisture contents were the highest in sultana and the lowest in sundried raisins, at all of investigated temperature levels. Critical water activity (CWA) and critical water content (CWC) were estimated from the state diagram and the relationship between water activity, the glass transition and the equilibrium moisture content. According to the state diagram specification, CWC (dry basis) and CWA of raisins were estimated lower than 0.03 and 0.05, respectively.
Ali Hassanpour; Mohsen Esmaiili; Asaad Modarres Motlagh; Alaoddin Rahmani Didar; Meghdad Nasiri
Abstract
In this study, to determine poisson’s ratio and modulus of elasticity of white seedless grapes during maturation, the fresh fruit samples were harvested from a vineyard at seven sequential weeks from 6th September to 18th October. In each run, six grape berries were randomly selected and the static ...
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In this study, to determine poisson’s ratio and modulus of elasticity of white seedless grapes during maturation, the fresh fruit samples were harvested from a vineyard at seven sequential weeks from 6th September to 18th October. In each run, six grape berries were randomly selected and the static loading test and digital photography were done together. Considering true shape of the fruit and an allowable deformation value, and also using Hertz’s theory with a true poisson’s ratio (experimental), modulus of elasticity was calculated. Apparent poisson’s ratio was determined by the image processing, too, and then obtained values of poisson’s ratio were modified using finite element software (ABACUS). Results showed that measured modulus elasticity by the Hertz’s theory depends on the magnitude of axial strain and increases with increasing that. Regarding the results, the calculated poissoon’s ratios are less than that true one, depending on the axial strain value. It was found that both modulus of elasticity and poisson’s ratio decreased during maturation.
Keywords: poisson’s ratio, modulus of elasticity, white seedless grapes
Razieh Dehbooreh; Mohsen Esmaiili
Abstract
In this study, the possibility of microwave finish drying for two types of dried grapes (Natural and Sultana) was investigated. The samples were washed in water bath at given temperature ranges (25 and 45 C) for 30 to 60 minutes. After dewatering the samples, they were dried using microwave (at two ...
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In this study, the possibility of microwave finish drying for two types of dried grapes (Natural and Sultana) was investigated. The samples were washed in water bath at given temperature ranges (25 and 45 C) for 30 to 60 minutes. After dewatering the samples, they were dried using microwave (at two powers: 270 and 450 W) and hot air convective dryer (at 50 C). Water gain (%), effective moisture diffusivity and Hunter values (L as lightness and a/b ratio) were determined. To determine a suitable model for describing finish drying behavior, ten commonly used mathematical models were compared according to the three statistical parameters: coefficient of determination (R2), chi-square (χ2), and root mean square error (RMSE). Results showed that water gain for sultana samples was 3-4.5 times more than that for natural raisins. Based on experimental drying rate data, drying took place in falling rate period. Among the models, two term model was most adequate showing highest R2 and lowest χ2 and RMSE. It was found that the drying method affect color indices of product and also the application of microwave finish drying technique depends on used microwave power and type of dried grape.
Keywords: Finish Drying, Microwave, Modeling, Dried grape
