IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2011 | Volume:8 | Issue:30 (SPECIAL ISSUE)|Papers Count:12

Iranian White cheese samples were ripened in three different brine concentrations including13, 10, and 8% of NaCl at 6±1oC for 56 days. The effect of brine salt concentration on chemical properties, concerning proteolysis and lipolysis as well as physical characteristics in relation to the texture of cheese samples were analyzed during ripening. Higher brine concentrations, resulted in higher salt content, total solids and pH, along with lower acidity. Evaluation of proteolysis in the cheese samples was performed using Kejeldal method, calculating soluble nitrogen fraction, as well as Urea-poly acryl amid gel electrophoresis. Our results showed that proteolysis is different in cheese samples according to their brine salt concentrations, and enhanced by reducing brine concentration. Lipolysis during aging was assessed applying the acid degree value (ADV) method. Results showed that the ADV was different in cheese ripened in variable salt concentrations. Cheese samples ripened in the highest brine concentration (13%) was harder than those ripened in the lower brine concentrations (8% and 10%).

One of the traditional products of southern regions of Iran is a fermented product called Mahveh. In this study, effects of garlic extract on chemical, microbial and sensory properties of Mahveh produced from fresh and dried anchovy (Stolephorus indicus), were investigated. The results showed that garlic extract had not significant effects on protein, fat, ash and moisture contents (P>0.05). The lowest values of TVN, TBA and FFA observed in Mahveh produced from the fresh anchovy with garlic extract, that were 321.82 (mg N/100g), 1.58 (mg MA/kg) and 16.95 (% oleic acid), respectively. Mahveh samples had a relatively high acidity, so that pH values of fresh and dried anchovy without and with garlic extract were 5.92, 6.02, 5.93 and 6.09, respectively. Also, antibacterial activity of garlic extract led to decrease of total viable counts in Mahveh produced from fresh and dried anchovy from 3.52 and 4.43 to 2.42 and 3.03 (log cfu/g). This decrease, were significant (P<0.05) for halophilic bacteria, too. Results of the color measurement showed no significant difference in a* and b* values for various treatments (P<0.05), but Mahveh produced from fresh anchovy was significantly more lightness (L*) in comparison with Mahveh produced from dried anchovy (P<0.05). According to the results of the sensory analysis, the odor was a limiting factor in acceptability of Mahveh. Generally, the results of this study showed that all of four types of Mahveh products made from anchovy were acceptable in view point of the chemical, microbial and sensory quality indices. Moreover, using the garlic extract resulted in improvement of the quality indices of Mahveh.

In this study, the efficiency of wheat quality classification tests with an emphasis on the novel glutenin macro polymer (GMP) test was evaluated. Wheat quality indicators such as Zeleny and SDS sedimentation tests were compared with GMP method in quality classification of several Iranian wheat cultivars. The results showed no significant correlation between protein content and breadmaking characteristics (loaf volume and height). Zeleny, SDS sedimentation and GMP tests showed significant correlation with loaf volume and height, but at different importance levels. PLS regression analysis indicated that GMP wet weight is the most important predictor for bread quality compared to other tests. Thus, GMP wet weight measurement can be regarded as a suitable predictive tool for bread quality, especially in wheat breeding studies where restricted amounts of samples are required. Based on all quality tests performed and the results obtained, PLS analysis was also to classify wheat cultivars examined into strong and weak quality classes.

In the present study, some industrial active dry yeasts were compared regarding CO2 production which is a factor for determining the fermentation ability. The industrial baking strains of Saccharomyces cerevisiae were isolated from commercial active dry yeast, afterwards the amount of CO2 production was measured in a model liquid dough media using the gas measuring system. The comparison between the amounts of CO2 production by standard and industrial strains of Saccharomyces cerevisiae revealed that rapid CO2 production in moderate sugar medium is the most important phenotype in strains which are suitable for producing the baker's yeast. This method is considered as a fast screening way for strains of Saccharomyces cerevisiae in laboratory scale for the purpose of selecting the optimum strains for producing bakers yeast. The more osmoresistance strains are more active in high sucrose medium. Therefore, these strains are useful for producing baker's yeast in the confectionary industry. One strain named K, showed appropriate biomass production. This strain had been highly active in high sucrose medium which makes it a good candidate for the production of bakers yeast in bakery and confectionary industry.

In this study the effect of hot water, acetic acid and sodium chloride solutions on the accelerated ripening of Mazafati date cultivar was investigated. Except for the cold storage control (Blank), other samples (control sample and samples that immerged in water, acetic acid (0.5, 1.5 and 2.5%) or NaCl (1, 2 and 3%) solutions with 60oC for 5 min) were incubated at 39±1 oC for 80 hrs. The results indicated that incubation was the main factor in ripening of the date and about 85% of the control samples ripened only by incubation. Acetic acid and NaCl solutions had complementary and accelerating effects. Total solids, total soluble solids and acidity of the samples increased while the pH, water insoluble solid, hardness and color parameters (L*a*b*) decreased during ripening for all samples except for blank sample. Overall, the treatment by hot acetic acid solution (0.5%) followed by incubation at 39±1oC can be used as a good candidate for accelerated ripening of Mazafati date.

This study was designed to evaluate the effect of edible coating (Carboxyl Methyl Cellulose (0.17%) and Low Methoxyl Pectin (1.5%)), concentration of osmotic solution (10% salt, 10% salt+5% sugar, 15% salt+5% sugar and 15% salt+10 %sugar) and immersion time (40, 60 and 80 minute) on osmotic dehydration of button mushroom. The result showed that the CMC coating improved the rehydration properties. Also, rehydration ratio increased as the immersion time and salt concentration in osmotic solution rose. The highest water loss related to CMC coating samples and the lowest solid gain achieved in control. Furthermore, the amount of water loss and solid gain increased with time and concentration of osmotic solution (p<0.01).

Nowadays, presence of enteric viruses in water and some foods is proved as a cause for infectious diseases. Raw milk can transmit enteric viruses potentially. Lack of distinct protocol for recovery and extraction of these viruses from raw milk made us to evaluate the effect of dry matter amount on quality and amount of viral RNA yield. Therefore according to reverse of routine protocols in separating of milk components, we prepared four milk model solutions in different combinations and ratios based on natural raw milk components. Then, each milk model solution was spiked with five levels of MS2 coliphage (1.3×104, 1.3×102, 1.3, 1.3×10-2, 1.3×10-4 pfu/ml). We isolated the viral RNA from each milk model solution using phenol - guanidine thiocyanat - chloroform method. Also we measured quality and RNA extraction Yield in twelve frequencies by nanodrop spectrophotometer. The results showed that in the equal viral concentration, the most amount of viral RNA was extracted from whole milk model solution (including fat). Whereas casein and whey proteins had the most inhibition in the viral RNA extraction .Also the highest quality of the extracted RNA for molecular detection was related to whole milk model solution. Based on response surface model (polynomial) RNA extraction yield and quality of the extracted RNA were closely correlated to the amount of dry matter of milk model together with coliphage concentration (R=0.96 and R=0.92 respectively).

In this study effect of flour hydration was investigated on gluten development in bread dough. For this purpose, zero-mechanical energy developed (ZD) doughs, which prepared and hydrated outside conventional mixers were used. Effects of fridge and room temperatures for different durations (1.5, 4 and 24 h) were studied on dough hydration extent and gluten development. Epi-fluorescence light microscopic (EFLM) observations revealed positive effect of holding time in both temperatures on protein distribution extent in dough microstructure. However, increasing temperature for durations studied showed strong effect on hydration and hence gluten development extent. So, treatments carried out at room temperature for 24 h compared to those accomplished at fridge temperature for the same duration showed the best gluten development patterns. Concluding, flour hydration leads to development of gluten structures in the dough. Gluten self-aggregation caused by hydration accounts for this phenomenon. However, the structures observed for ZD doughs in this study were different from those reported for optimally-mixed doughs, which show coarse interconnected gluten network surrounding starch granules.

Cultivated mushrooms are considered as a popular delicacy and have an important role in daily intake due to essential Amino Acids, elements and vitamins. Based on Several Studies, mushrooms can accumulate great concentrations of toxic metallic elements like lead and cadmium in Comparative to other Fruits and vegetables. This study has conducted due to following reasons: -Lead and Cadmium have Considerable toxic effects even in low Concentrations.-There is no reports about these elements contents in mushrooms cultivated in Iran.-There is no Proper strategy for this infection control Material and Method: 8 mushroom Samples were collected randomatically from mushroom sale centres in Tehran, and delivered to laboratory. Then they were sorted, cut, washed, and dried at 80oc for 20h. Dried Samples were homogenized and laid in ash. Then they were Solved in Nitric Acid and finally analysed by Atomic Absorption Spectrometer.Results: Cadmium Content was lower than acceptable level (EU 466/2001) (2.0 mg/kg dry weight) in all samples. Lead content was generally lower than acceptable level (3.0 mg/kg dry weight) except for 2 Samples which have 5.35 mg/kg and 3.71 mg/kg Lead Content.Conclusion: Analysed Samples have low content of cadmium due to cultivating environment, good quality of Compost and irrigation with deep underground water.Geographical Condition of Cultivation may cause high content of lead in two Samples. It is recommended to investigate the main reason of this infection.

Chitosan as a biopolymer has numerous applications in agriculture. Coating fruit and vegetables with chitosan has some positive advantages for the long-term storage of them, because the film of chitosan provides a kind of an active package which inhibits fungal growth and maintains the quality properties of the fruit for a longer time. In this study, the effects of chitosan in extending shelf life of grape (Shahroodi) and quality properties were investigated. The fruits were treated with aqueous solutions of 0.5 and 1% chitosan and then stored at 2ºC and 90% relative humidity for 90 days. Changes in weight loss, color, pH, decay and sensory quality were measured. Results suggested that chitosan reduces weight loss, decay, browning, cracking and shatter also increases quality of berries. However, there was no significant different between two chitosan coating concentrations, but in some cases 1% chitosan showed better results than 0.5% for shelf life extension and quality maintaining.

Tea is one of the most popular drinks in the world and because of its health benefits to human it has got considered as a medicinal plant. Tea plant (Camellia sinensis) can uptake metal elements particularly Aluminum and accumulate them on different parts of the plant. There are reports on the relation of the heavy metals Arsenic and Aluminum with disease like Alzheimer's. Because of the high consumption of tea in our country and the adverse effects of the elements like Al, Cd, Sr, Pb, Ni and Co on human health, the aim of this study was the determination of these elements in tea. Four groups of Tea samples (Iranian tea, imported tea, mix tea and tea bags (four samples for each group) were selected randomly and purchased from local supermarkets (Sharvand or Refah) in Tehran. Samples prepared by wet ashing method by the application of concentrated chloric acid & nitric acid, then the elements were determined in Inductively Coupled Plasma-Optical Emission Spectrophotometer (ICP-OES). All the tests were done on duplicate basis. For the evaluation of statistical parameters, mean and standard deviation, non-parametric test (Kruskal-wallis) and both one way and two way variance analysis were applied. For evaluation of the data the SPSS version 13 software was used. Results showed that the amount of elements Pb, Co, As and Cd in all tea samples were lower than instrument detection limit (0.14, 0.05 and 0.015 ppm, respectively). There were significant differences in total amount of Al in between tea groups (p<0.05). For Ni there were no significant differences in between tea groups. In the case of Sr there were significant differences only in imported tea groups with the others, but also there were significant differences in the samples of each group (p<0.05). This study indicated that the levels of the elements in most Iranian tea samples were higher than other tea types. In order to solve the tea production and processing problems more researches should be done on these areas.