مجله علوم و صنایع غذایی ایران
سال هشتم شماره 3 (پیاپی 31، پاییز 1390)

Now days، nutritional labeling of fish edible products and calculation of its fillet yield are important needs for fish processing industries. The present study was done to investigate Determination of chemical composition and fillet yield of silver carp (Hypophthalmichthys molitrix) for grading and nutritional labeling of its products by regression equations. For this purpose 50 specimens silver carp were applied in marketing size and their fillet yield، moisture، lipid، protein، ash and energy content were measured. Then، the relationships between these parameters with total length were considered and type of relationship and equation of them were determined. According to obtained results، the relationship between moisture content with fish total length was in inverse linear regression form (p<0. 05)، while the relationships between lipid، protein and energy content of fillet with fish total length was in positive linear regression form (p<0. 05). In generally these equations was in Y= bX± a form. The relationship between protein content and fish total length was significant but weak. According to obtained results there is not relationship between fillet ash content and fish size. Regarding these results and determining their equations، fish length can be used for fish sorting by sorting machine and then economic calculations and determination of moisture، lipid، protein and energy content by obtained equations were done for each group and finally، nutritional labeling and deciding for processing were done for each group.

Paying a heavy subsidy just on N and P-fertilizers has caused farmers to overuse these fertilizers in the country and hence، more than 90% of the fertilizer use constitutes N and P-fertilizers on the irrigated wheat farms. Due to continuous imbalanced fertilization، especially the overuse of P-fertilizers and the absence of Zn-fertilizers in the farmers’ conventional fertilization practice، there has been an increase in the concentration of phytic acid (C6H18O24P6) in the wheat grains. Increased level of phytic acid (PA)، would lead to a high molar ratio of phytic acid to zinc (PA/Zn) in wheat grains up to around 60. Phytic acid combines with metal cations in the digestive system and converts them to phytate complexes which do not get absorbed in the human body. Presence of higher PA has been mentioned as a reason for discarding the wheat bran. Removing bran from the wheat grains is the fastest and easiest way of discarding PA. According to the World Health Organization (WHO)، for absorption of nutrients by digestive system in human body، PA/Zn index must be less than 25. Due to calcareous nature of the studied soils and continuous imbalanced fertilization، especially the overuse of P-fertilizers، PA/Zn molar ratio is around 60. Since the main part (70%) of mineral nutrients، vitamins and PA are accumulated in the wheat bran، the authorities; instead of scientifically solving the problem- i. e. reducing PA and increasing Zn concentration in wheat grains- have decided to take away bran from the wheat kernel in the process of flour preparation. By removing subsidies in the 5th Development Plan، since the price of bread will increase significantly، so it is necessary to increase the quality of the bread. To achieve high quality bread، concentrations of PA and Zn should decrease and increase، respectively. This is possible only through the enrichment of wheat in the farm by the use of balanced fertilization، eliminating subsidy on P-fertilizers and allocating subsidy to zinc، bio- and organic fertilizers in order to reduce PA/Zn index. Various studies in the past two decades have shown that if current imbalanced fertilization is continued، PA/Zn index will be well around 60، necessitating the removal of the bran. But، if balanced fertilization is adopted as a general practice by the country''s farmers، this ratio will decrease and it will not be necessary to remove the bran in flour processing. It is suggested to remove the subsidy from N and P-fertilizers and allocate them to Zn، biological and organic fertilizers، as well as conducting soil and plant analysis to determine required fertilizer levels. Phosphate fertilizers must be given to the farmers only on the basis of soil tests. Imposing heavy penalties on the bakers who illegally use baking soda instead of yeast and implementing optimal fertilizer management practices will result in crop enrichment in wheat farms، which، in addition to achieving sustainable production of healthy crops، will contribute to upgrading Iranian society’s health-rating. By practicing balanced fertilization، applying zinc sulfate and bio-organic fertilizers، the country''s nutrition will improve and the quality and quantity of whole wheat bread will be upgraded significantly، and hence the problem of malnutrition will be solved in the Iranian society.

Enzymes of wheat flour have an important role on the quality of various backing products، especially bread. The knowledge of their activites can assist us to produce the high quality products. On the other hand، the most wheat flours in the countery have low α-amylase activity. Therefore، optimization of flour α-amylase activity is important for production of high quality bread. In the present work، chemical properties of three wheat flours varieties (Mahdavi، Kavir and M7318 that are produced in Isfahan province) were investigated. To show the changes of α-amylase activities، the activities of enzyme were measured during the germ growth times up to 72 hours. α-amylase activity of flours was also optimized according to falling number 250. The effect of this optimization on the bread texture in four different times after baking were then evaluated. The results showed that all three varieties had lower levels of α-amylase activity than the optimum level. The results indicated an increase in the activity of α-amylase during the growth of germ up to 72 hours. The results of the determination of the best blending percentage of germinated wheat flour with baking flour indicated that optimization of α-amylase activity is essential in terms of both wheat varieties of flour and germination times of wheat germ. Bread texture analysis indicated that bread produced with optimized α-amylase activity flours using appropriate percentage of germinated wheat flour have softer texture and lower staling. Wheat variety had also an important effect on staling so that bread produced with Kavir variety flour had softer texture than other varieties. Breads produced with optimized flour using 72-hours germinated wheat flour had softer texture than the breads made by optimized flours with other germination times.

Salting and vacuum packaging، each of them has disadvantages for fish preservation in non-frozen mode. This study was aimed to investigate the The effect of light salting، vacuum packaging and their synergistic effect on on shelflife of rainbow trout (Oncorhynchus mykiss) fillet during storage at 4°C±1. For this purpose the rainbow trout fillets were brined in 10 salt solution and vacuum packaged. Measuring of PH، total volatile bases nitrogen compounds (TVB-N)، tiobarbitoric acid (TBA)، total viable microbial count (TVC) and sensory evaluations، were performed during 18 days in refrigerator temperature. Obtained results showed that all of chemical and microbial indices increased during storage period. PH، TBA and TVB-N indices and microbial growth in salted، vacuum packaged was lower than other treatments and in light salted treatment was lower than control group (p<0. 05). The results of sensory evaluations showed that light salting of rainbow trout fillet situation improved these indices rather than control group. Salted vacuum packaged treatments had a better sensory evaluations scores than salted treatment (p<0. 05). with regarded to allowable restrict of TVB-N indices (25 mg/100g fillet) and total viable count (6 Log cfu/g) and also sensory evaluations، light salting and salted vacuum package treatments increased the shelflife of rainbow trout fillet in 4°C about 3 and 7 days، respectively and the major problems of each method of salting and vacuum packaging was removed.

In this study gelatin was used as a fat replacer in the production of a low fat cream. The fat content of the control cream was reduced from 30% to 20%. Gelatin was used at 5 levels: 0، 0. 25، 0. 5، 0. 75 and 1%. Viscosity، Bostwick consistency، textural hardness، color parameters (L، a، b) and sensory characteristics of the five low fat cream samples with 20% fat were compared with the 30% fat control. The results indicated that gelatin was able to improve the properties of low fat cream samples towards the 30% control. In terms of color parameters the low fat creams with 0. 5% gelatin and more were similar to the control with 30% fat. Sensory evaluation tests showed that the perception scores of the low fat creams with 0. 75 and 1% gelatin were the same as the 30% fat control.

The effect of microwave، grilling، steaming and shallow fat frying was evaluated on lipid content and oxidation and also fatty acid composition in S. commerson. Total lipid content was 2. 31، 4. 02، 2. 62، 3. 60 and 4. 77 % for raw and microwave cooked، grilled، steamed and shallow fat fried samples، respectively. The FFA، PV and TBA content was 4. 32 %، 3. 00 meq/kg and 0. 60 mg/kg in raw samples. There was no significant difference in FFA content between raw sample and grilled، steamed and fried samples and also in PV content between raw and cooked samples. The TBA content increased to 1. 58، 1. 09، 1. 80 and 1. 40 mg/kg in microwave cooked، grilled، steamed and shallow fat fried samples، respectively. 23 different fatty acids were found of SFA، MUFA and PUFA groups. The n-6/n-3 ratio was 0. 80، 0. 80، 0. 70 and 0. 76 for raw and microwave cooked، grilled، steamed samples، respectively and significantly increased to 2. 59 in fried samples. Cooking by different methods affects on total lipid content، fatty acid profile and the lipid stability of fish samples. The changes on chemical characteristics of fish lipid by different cooking methods were in acceptable range and were not detrimental on fish quality.

Walnut (Juglans regia L.) is one of the most important horticultural crops in Iran. Walnut fruits are rich source of essential compounds for human health. In the present research twelve walnut genotypes were selected in Markazi province in fourdifferent geographical locations، based on their regular bearing and high productivity. Selected genotypes were evaluataed for several pomological properties during 2007 growing-season. Results showed that، nut and kernel weights varied from 7. 46 through to 15. 25 g and 3. 77 through to 8. 1 g، respectively and kernel nut percentage was 45. 97 to60. 51%. Oil and protein contents also varied from 51. 0 to 73. 0 % and 10. 15 to 14. 55%، respectively. The results showed that genotype of MS15 had the highest nut and kernel weights (15. 25 and 8. 1 g، respectively). MS43 showed highest kernel and oil percentage (60. 51 and 73. 06%، respectively) and MS12 highest protein ratio (14. 55%). The fruits of superior selected genotypes can be used in food industry.

The citrus fruits are rich in flavonoid compounds. Flavonoids are polyphenolic compounds that exhibit valuable effects such as anti-cancer properties. Thus، this study was aimed to determine the levels of hesperidin، naringin and rutin presented in various lime (Citrus aurantifolia) fruit tissues during fruit growth and maturation. This experiment was laid out as a completely randomized blocks design with four replications. Extraction was carried out using methanol and dimethyl sulfoxide and quantification was done with the help of HPLC technique. The results showed that hesperidin was the predominant flavonoid in lime fruits. The highest amount of hesperidin and naringin was observed 30 days after fruit set (3. 23 and 1. 63 % in dry matter، respectively) and was decreased afterward until fruit maturation time. The hesperidin and naringin were found in maximum quantity in peel. The rutin flavonoid was produced in fruit pulp at 50 days after fruit set. None of the flavonoids was present in lime seeds.

Nowadays، Probiotic products are defined as the processed products which contains viable probiotic bacteria in a sufficient concentration when they administered in adequate amounts، confer a health benefit to the host. The objective of this study was evaluation of the Iranian white cheese as a food carrier for probiotic bacteria (including Lactobacillus and Bifidobacterium species). Survival of Lactobacillus plantarum، Lactobacillus bulgaricus (sp)، Bifidobcterium animalis and Bifidobacterium angulatum were determined by evaluation of the bacterial growth on the selective media in laboratory in different interval of production and preservation of Probiotic Iranian white cheese. B. animalis showed the highest viability in nonstarter treatment and L. bulgaricus (sp) in treatment contained starter culture showed the lowest viability at the end of storage period of cheese. Survival Properties of Lactobacillus species were completely different from Bifidobacteria species in Iranian white cheese. However، the population of lactobacillus and Bifidobacteria species decreased gradually during ripening in this cheese but was always higher than 106 CFU/g at the end of ripening storage.

The mechanical losses which occur in agricultural products are the damage''s which imposed on country economy. It is important to investigate the bruising phenomena، as an index of mechanical losses for loss reduction and optimization of harvest and postharvest machinery. In the current study، by means of an impact pendulum apparatus and by conducting a series of impact tests، the effects of temperature (0، 10، 20 and 300C)، variety (Golden Delicious and Red Delicious)، padding surface (corrugated carton، rubber and galvanized iron) and kinetic energy (300، 600 and 900 mJ) were investigated on rate of apple bruise. Statistical results showed that the effect of temperature، variety، padding surface and impact energy were significant on the mean value of bruise volume at 1% of statistical level. By increasing temperature، the bruised volume was decreased، whereas it increased by increase of energy level in both varieties. While، the Golden Delicious had more strength than Red Delicious. Also، the maximum rate of bruised volume was related to Red Delicious in contacting to galvanized iron and the minimum rate was related to Golden Delicious in contacting to corrugated carton. Prediction of bruised volume was provided using artificial neural network based on four factors of: temperature، impact energy، padding surface and variety. Multilayer perceptron of neural networks were used for prediction of bruised volume. In comparison with other topologies، algorithm Levenberg-Marquardt had better performance with structure 1-26-4 and logsigmoid transfer function in hidden layer. Based on this algorithm، the mean of prediction accuracy in training، evaluation and testing process was equal to 92. 48، 88. 94 and 87. 72 percent، respectively. In addition، the correlation coefficient (R) was calculated equal to 0. 975 for linear regression between predicted model and experimental data.

g-oryzanol is an unsaponifiable component of rice bran oil، composed of several kinds and has antioxidant activity similar to tocopherols. In order to separate g-oryzanol، four varieties of rice from north part of Iran have been selected. These varieties include «local Tarom»، «Fajr»، «Shirudi» and «Neda». rice bran oil was subjected to oil extraction after thermal stabilization. Column and HPTLC chromatography followed by GC/MS were employed for separation، purification and identification of g-oryzanol. The antioxidant activity of the isolated concentrates were determined 0. 01، 0. 05 and 0. 1 percent on tallow، a substrate suitable to evaluate antioxidant activity due to the lack of natural antioxidants. The results indicated that «Neda» variety had the highest content of oil and g-oryzanol but the obtained g-oryzanol from «local Tarom» variety showed the highest antioxidant activity.

Using soy products as an ingredient in ice cream formulation lead to a food product with unique nutritional and functional properties and reduces the cost of final product. In this project the effect of substitution of milk solid non fat (MSNF) with soy flour on flow behavior and rheological properties of hard ice cream was studied. The formulation of ice cream samples consisted of 10% fat، 12% SNF، 18% sugar، 0. 4% stabilizer and 0. 1% vanillin as flavoring agent. Substitution of MSNF was done at four levels: 45، 55، 65 and 75%. Rheological measurements of ice cream mix samples were carried out after 24 hours aging at 4·c. According to the obtained results، all sampled showed psuedoplastic behavior and apparent viscosity decreased with increasing shear rate. Increasing the level of soy flour substitution resulted in decreasing flow behavior index and therefore significantly increased the shear thining behavior of the samples (α<0. 05). Also، consistency index and apparent viscosity increased with increasing the amount of soy flour especially from 65 to 75%.

Pomegranate seed oil is rich in functionally and nutritionally important compounds and hence has a wide application in food، pharmaceutical and cosmetic industries. In this study the effect of high power ultrasonic waves and pretreatment method on the extraction efficiency of oil from pomegranate seeds was investigated at a frequency of 20 kHz. Variables in question were extraction procedure at 2 levels (solvent extraction with and without ultrasound)، extraction time at 3 levels (30، 45 and 60 minutes) and pretreatment of seeds and sample preparation at 6 levels (grinding، soaking and grinding، sonication and grinding، soaking، sonication and grinding، grinding، sonication and dehydration، and soaking، grinding، sonication and dehydration). The results showed that ultrasound significantly increased the extraction efficiency with no effect on the composition of fatty acids and their quantitative values. It was also found that pretreatment of whole seeds by sonicating them in hot water led to highest extraction efficiency. Moreover، the extraction time decreased to 30 min in the presence of ultrasound waves.

In the recent years، interest in the use of biodegradable biopolymers for packaging applications has raised. One of the potential uses of these biopolymers is for production of active packaging containing antimicrobials. In this review manuscript، has presented some examples for applications of these packaging materials for different foods and then has mentioned the different kinds of antimicrobial agents that may be incorporated in their formulations. Many factors are involved in designing the antimicrobial packaging system. Most factors are closely related to the chemical characteristics of antimicrobial agents، the nature of the food and target microorganisms that all will be discussed in this paper.