Food Technology
Mahya Hosseinzadeh; Mohammadyar Hosseini; Mohammad Shahedi; Mehdi Kadivar
Abstract
Introduction
The most important component of wheat proteins is gluten, and the most prominent bonds in gluten are disulfide bonds, which bind glutenin subunits. Therefore, oxidizing and reducing agents with great effects on the thiol-disulfide system of the dough can change the mechanical and rheological ...
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Introduction
The most important component of wheat proteins is gluten, and the most prominent bonds in gluten are disulfide bonds, which bind glutenin subunits. Therefore, oxidizing and reducing agents with great effects on the thiol-disulfide system of the dough can change the mechanical and rheological properties of the dough. Due to the positive effects of ascorbic acid on the properties of the dough, it is used as a flour improver. To weaken the structure of the dough, reducing agents such as cysteine-L can be used, and by adding organic acids, increasing the specific volume and decreasing the moisture, the pH and hardness are observed in comparison with the control. This study is performed to evaluate the effect of adding reducing compounds, vitamin C and organic acids during the conditioning of wheat and their effect on the yield of the resulting pulp.
Materials and Methods
First, Physical properties of wheat include: specific density, colorimetry, estimation of grain length, width and thickness, grain hardness, hectoliters, 1000-grain weight, grain moisture, degree of extraction were measured for the tested wheat. Moisture, pH, ash, particle size, fat, protein and zeal number tests were performed on wheat flour. From elementary cleaned and weighed wheat, 13 samples of 240 g each were weighed separately and poured into plastic bottles. One sample was conditioned with only 30 ml of distilled water and the other 12 samples were conditioned with the following solutions, respectively:
1- Cysteine solution at three levels of 0.25, 0.5 and 0.75% by weight
2- Citric acid solution in three levels of 0.3, 0.4 and 0.5% by weight
Vitamin C solution in three levels of 100, 150 and 200 ppm
4- solution of 80 ppm vitamin C and 0.1% cysteine, solution of 100 ppm vitamin C and 0.2% cysteine, solution of 120 ppm vitamin C and 0.3% cysteine
After 24 hours, the conditioned wheat samples were milled by a laboratory waltz mill, and then subsequent tests including gluten, sulfhydryl-disulfide, glutathione, and solvent retention capacity (SRC) were performed on the samples.
Statistical analysis was performed using SAS statistical software in a randomized complete block design. Each measurement was performed in at least three replications and the means were compared at 95% confidence level with the least significant difference in LSD.
Results and Discussion
The results of physical tests on wheat grain and chemical tests on flour obtained by milling the wheat samples without adding additives during conditioning are presented in tables. The results of gluten, glutathione, sulfhydryl-disulfide and solvent storage capacity tests on samples of conditioned wheat flours are also presented. Based on the results of gluten and glutathione test, it was shown that ascorbic acid is oxidizing and strengthening the dough, but cysteine is reducing and weakening the dough. Simultaneous addition of cysteine and ascorbic acid strengthened the dough, adding citric acid to certain level strengthened the dough as exhibited in the gluten test. However, byond that level, weakened the dough, but in the glutathione test it was almost ineffective. The results of sulfhydryl-disulfide test showed that increasing the amount of vitamin C at three levels of 100, 150 and 200 ppm increases the number of disulfide bonds, although this increase was not in linear trend, which can be due to the limited number of groups of sulfhydryl with a suitable spatial arrangement for oxidation. Accordingly, the number of sulfhydryl groups is significantly reduced, although it does not reach zero. With the addition of reducing cysteine, the opposite trend was the case, as the number of thiol groups increased, the number of disulfide bonds and bridges decreased. The addition of organic acid had no significant effect on both parameters and showed that the performance of these two variables is independent. By adding both reducing and oxidizing compounds, it was found that the oxidizing effect of vitamin C is far greater than the reducing effect of cysteine. Regarding the solvent retention capacity test performed with 4 solvents of deionized water, 50% sucrose, 5% sodium carbonate and 5% lactic acid, the expected results are that the addition of cysteine has a reducing and weakening effect on the dough, adding vitamin C and cysteine + vitamin C strengthens the dough and the addition of citric acid initially strengthens the dough, but by increasing its level weakens the dough, but this effect is small and can beneglected . The results obtained by comparing the samples conditioned with cysteine, vitamin C, citric acid and cysteine + vitamin C, with the sample conditioned with distilled water in some additive levels matched the expected results, but in some cases did not.
Foroozan Jafari; Nafiseh Zamindar; Mohammad Goli; Zahra Ghorbani
Abstract
Introductıon: In developing countries, camel meat is used to provide nutrients, proteins, vitamins, and minerals but it usually has a tough texture. Marinating meat may improve its flavor and tenderness. It has been shown that plant enzymes such as papain, ginger, and Cucumis increase the meat's tenderness ...
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Introductıon: In developing countries, camel meat is used to provide nutrients, proteins, vitamins, and minerals but it usually has a tough texture. Marinating meat may improve its flavor and tenderness. It has been shown that plant enzymes such as papain, ginger, and Cucumis increase the meat's tenderness and improve the flavor and aroma of the products.Ginger extract (GE) could improve the tenderness of camel meat by “Zingibain”. Marination in acidic solutions has been used both traditionally and industrially for the tenderization and flavoring of meat (Abdeldaiem and Hoda., 2013; Tsai et al., 2012). The tenderization effect of marination on meat have been examined by using organic acids such as citric acid (Aktas et al., 2003; Berge et al., 2001; Ke et al., 2009; Kim et al., 2013; Ke, 2006; Ke et al. 2009).The objective of this study was to evaluate the effect of ultrasound and marination with different concentrations of citric acid and Ginger extract 30% on the physicochemical characteristics of camel meat. Materials and methods: Fresh ginger rhizome (Zingiber officinalis roscoe) purchased from a local market was washed, peeled, sliced and immediately homogenized with an equal quantity of chilled and distilled water (4ºC) for 2 min to extract the crude enzyme. The homogenate was filtered through Buchner funnel and the water to get the GE. Marinade solutions were prepared by the addition of 0.5, 1 and 1.5% citric acid to 30% GE, and distilled water was used as control. To prepare the required 30% GE, the crude fresh GE was diluted with distilled water (He et al., 2015).The portions from Biceps femoris muscles of aged male camel carcasses (4 years of age) were prepared according to the method described by Abdeldaiem et al (2013). Uniform sized (3×3×3 cm) of aged camel meat chunks were dipped in the curing solutions at the ratio of 3:1(meat: liquid) and immersed in the polyethylene bags and kept at 4±1°C for 24 and 48 h (Abdeldaeim et al., 2014; Garge et al., 2006).The pH values were measured directly using a probe-type electrode (Naveena et al., 2004). Uptake of the marinade (%) was measured according to the method described by Garg et al (2006) and Hosseini et al (2012).The color measurements; lightness (L*), redness (a*) and yellowness (b*) were performed at the surface of the marinated meat samples (Barbut, 2004).Cooking loss of meat samples was determined so that He et al (2015) and Kim et al (1995) described.Shear force values of cooked samples were determined using texture analyzer with Warner-Bratzler shear apparatus, while muscular fibers were almost parallel to the force as normally occurs during chewing. Six meat cores (1.27 cm diameter) parallel to muscle fiber were sheared once through the center by a warner-Bratzler shear attachment using 50 kg compression load cell and 200 mm/min cross-head speed (Karimi et al., 2008; Hosseini et al., 2012).After 24 and 48 h marination, samples were prepared for (SEM) as described by Naveena et al (2004).A completely randomized design in a factorial experiment with 3 replications was employed by using analysis of variance (ANOVA) to study the effect of ultra-sonication, and time on the physicochemical properties of camel meat. Least significant difference (LSD) test was used to determine differences between treatments means (P<0.05). Data were analyzed using the procedure of SAS version 8 (Burke et al., 2003). Results and discussion: Ultrasonication caused a decrease in pH while increasing marination time caused an increase in pH of all samples compared with control. Cooked samples showed higher pH compering with raw marinated samples. Ultration and increasing marination time caused a significant increase in marinade uptake due to structural changes. Application of ultrasound, the higher concentration of acid in marinade solution and longer marination period resulted in lower shear forces of meat samples.Marination by 30% GE in addition to 1.5% citric acid and ultration illustrated maximum tenderness, lower pH and L*-value but caused less water holding capacity and higher cooking loss.
Mohammad Sani Shariatpanahi; Seyed Hamidreza Ziaolhagh
Abstract
Since the waste of agricultural and horticultural products is high, appropriate methods should be used to produce products with high quality and shelf life for export. In Iran a great part of fruits and vegetables are dried conventionally and farmer use So2 gas for preservation and color stability of ...
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Since the waste of agricultural and horticultural products is high, appropriate methods should be used to produce products with high quality and shelf life for export. In Iran a great part of fruits and vegetables are dried conventionally and farmer use So2 gas for preservation and color stability of dried apricots ,but this gas is allergic and carcinogenic and effort to find suitable substitutes for this substance would be an efficient method to the health of the society. So, in this study 3 apricot varieties were selected to evaluate the drying quality and to determine the so2 replacement methods. The selected varieties (Noori, Khaybei 2 and Nasiri) were treated with citric acid, (0.3%), ascorbic acid (0.3%), sodium meta bisulfate (0.4%) and a 50% mixture of ascorbic and citric before drying and then were compared with control samples(without any treatment). After drying, the characteristics such as Brix, pH, moisture contents, browning index, acidity and organoleptic properties were evaluated. Results showing that the effect of variety on moisture, browning, pH, acidity and organoleptic properties were significant (P
Abdolhossien Aghababaei; Reza Kasaai
Abstract
Pollution arising from plastic waste materials caused a great worry for researchers who are interested in protection of environment. This problem shifts their subject to bio-polymers for applications in packaging industries. However, their low water barrier properties are a critical problem. The effects ...
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Pollution arising from plastic waste materials caused a great worry for researchers who are interested in protection of environment. This problem shifts their subject to bio-polymers for applications in packaging industries. However, their low water barrier properties are a critical problem. The effects of citric acid and methyl cellulose on water vapor and oxygen permeabilities and mechanical properties of starch composite thin films have been studied. Water vapor permeability (WVP) has been measured using a vial coated by a film. Oxygen transmission rate (OTR) of a film was determined from measurement of peroxide value for a definite amount of oil that is placed in a vial and coated by the film. Mechanical properties were measured using a tensile machine. Increase in citric acid concentration up to 5% citric acid (w/w), resulted in a decrease in water vapor and oxygen permeabilities. A film containing 5% of citric acid exhibited a minimum value for WVP, whereas the value of WVP and elongation at the break increased and tensile strength decreased for a film containing 20% of citric acid (w/w). Increase in methyl cellulose up to 30% resulted in decrease in WVP and OTR.
