مجله علوم و صنایع غذایی ایران
سال چهارم شماره 2 (پیاپی 12، تابستان 1386)

In this experiment the effects of preharvest calcium chloride and postharvest hot water treatment as well as the use of polyethylene bags for packaging on the quality improvement of pomegranate fruit during cold storage were studied. For this purpose Calcium chloride was sprayed at two levels on August 2004 (1% and 2%). Pomegranate fruits of Malas - Torsh cv. was harvested at fully ripen stage and treated with hot water (45، 50 and 55C for 20 minutes، 1 minute and 30 second espectively). Thereafter each fruit was warped up in a polyethylene bag and stored in cool store room with 1C and relative humidity of 85% for 3 months. The experiments were conducted using a completely randomized design of three replicates. The results indicated that fruits wrapped with polyethylene had a significant effect on preventing weight loss، improving the appearance as well as marketability of fruits during storage، while showing no effect on pH، TSS and fruit dry matter. Also it was observed that fruits treated in 50''C hot water showed significant improvement of quality while treatment with 45C hot water failed to show such effects. In total، a combination of Calcium chloride and polyethylene bag packaging along with 50C hot water treatment caused improvement in the general quality of stored fruit and decreased fungi infection and chilling index.

In this study، 270 samples of liver، muscle and kidney of broiler were collected from 90 farms in Tehran province during a year and analyzed for enrofloxacin residue by High Performance Liquid Chromatography (HPLC). Results showed that all the samples are contained enrofloxacin and in 22 (24. 44%) of farms enrofloxacin residue was higher than maximum residue level. The enrofloxacin residue in 8 samples of muscle (8. 88%)، 12 samples of liver (13. 33%) and 22 samples of kidney (24. 44%) was higher than maximum residue level. The mean value of enrofloxacin concentration in muscle، liver and kidney were respectively: In conclusion، this study confirmed widespread misuse of enrofloxacin in farms and lack of implementation of recommended withdrawal times. Moreover this study stresses، the need for stricter regulation for the use of antimicrobial drugs in the poultry industry as well as the inspection of chicken for residues prior to marketing.

Addition of 8%، 12% and 16% skim milk to fresh whey was studied to prepare indigenous fermented milk by industrial method. G3mix mesophil starter culture and Y709، V2 thermo Phil starter cultures were used and fermentation was performed with 2% starter cultures. The effect of the essence، the amount of skim milk added to whey، the percentage of salt added to fermented milk beverage and the presence or absence of gas was studied in the samples. Results show that carbonated samples containing spearmint or pennyroyal essence with 1% salt and 16% skim milk is the best desirable among others. The desirability of the samples containing Y709 starter culture at the above levels is comparable to the extent of the market samples and samples containing V2 and G3mix starter cultures were lower desirability respectively. The amount of total solid content of samples containing G3mix، V2 and Y709 starter cultures are 6. 98%، 6. 37%، 6. 06% respectively as compare with the market sample of 5. 02% is obviously higher. The fermented milk beverage produced form whey being cheep، desirable quality، easily competitive with market samples and can be produced industrial.

The goal of this study was to determine the changes of diacetyl content and sensory charactristics of yoghurt fortified with whey protein concentrate instead of skim milk powder at storage condition. Our finding showed that with increasing in amount of whey protein concentrate in yoghurt samples، diacetyl level was always higher than control sample. Diacetyl amounts also in yoghurt samples increased during two weeks. The results of sensory evalution also showes that there was no difference in flavour between control sample and sample C but quality characteristics (flavour، general acceptance) other samples were different from control sample. Results indicated that during storage period quality characteristics، especially improving consistency، creamy texture and more flavouring compounds produced acceptance sample C were close to control sample.

There are many reports about antibacterial potency of natural honey. Theses reports are confirmed preventive efficacy of honey on various different kinds of bacteria. The most important antibacterial factors of honey are phytochemical materials. These substances are derivatives from plants flora of bee culture’s region. We designed this study in order to assess the antimicrobial efficacy of honeys produced different regions of Urmia. This investigation was performed on samples collected from 5 honey production’s regions (Marmishoo=1; Nazloo= 2; Ghasemloo valley= 3; Marghevar= 4; Targhevar=5). 20 samples were collected from each region. Samples were cultured on blood agar media in order to confidence of lack of previous contamination. Then samples were cultured on standard bacterial culture include: Staphylococcus aureus (ATCC25923)، Escherchia coli (ATCC25922)، Pseudomonas aeruginosa (ATCC27853). Inhibition zone (IZ) and Minimum inhibitory concentration (MIC) were measured for each bacteria after incubation period. According to results of our experience، Targhevar honey posses more (IZ) and lesser (MIC) in compared to other samples. (p<0. 05) Difference between samples is thought to be due to existence of special phytochemical substances in plant flora of Targhevar region. These materials should be extracted and collected and used in production medical honey. The selection of special region for bee keeping is very important in process of monofloral medical honey production.

Nowadays the lack of food specially protein is the most important problem. Because of the increasing of the world population the need for food is increasing day by day for this reason researches are searching for cheap resources of protein for people. Whey is by- product of cheese factory. whey provides ecological problems because of having high COD. According to these problems many researches have been done on whey and different products were achieved such as single cell protein. In this research، the production of single cell protein from whey and trichosporon yeast are studied in external loop airlift reactor. Effective factors on gas hold up Such as air giving، ratio of down comer diameter to riser diameter and height of liquid in gas separator were studied and optimized. In this optimized situation the rate of single cell protein was achieved. The results of experiments showed that optimimum value for air giving intensity was 2. 27 cm/s، ratio of down comer diameter to riser diameter was 0/5 cm and height of liquid in gas separator was 3 cm. In this optimum condition، the amount of single cell protein was 18. 9 g/l. The rate of single cell protein in stirred reactors and bubble column was 10. 38 and 17. 3 g/l respectively in other''s researches. In comparison، external loop air lift reactor showed an increase about 8. 5 percent to bubble column and 45 percent to stirred reactor in producing single cell protein. So external loop air lift seems suitable in producing single cell protein. producing single cell protein can be studied in Other air lift reactors such as internal loop airlift reactors and obtained results can be campared with the results of this research.

Leguminous crops، chickpea specifically، are usually hand-harvested for several reasons: lack of dedicated combines، small field sizes and short plant canopies. Chickpea losses and kernel damages are in the form of emberyo damage، kernel breakage or scratching and splitting. In this research، three varieties of chick pea (Bivanij، ILC482 and Philip 93-93) at three level of moisture content (15-16، 20-21 and 25-26 percent on wet bases) and two loading directions were tested under compression loading. Independent variables were force and energy of rupture، stiffness، and deformation at the rupture point as well as some physical properties. Effect of moisture content on chickpea mechanical properties was found to be very significant (0. 01). Increasing moisture content، results in significant decrease of rupture force، energy and stiffness on one hand and increase of deformation on the other. Minimum and maximum values of rupture energy were obtained to be 24. 7 mJ at 25% mc wb، and 156. 3 mJ at 15% mc wb، respectively، both in the longitudinal loading direction. Results of test indicated that splitting of peas is most probable at 25 moisture content under length compression. Among the three varieties of chickpea، ILC 482 variety was most sensitive to splitting. Logarithmic regression equations were obtained having R2 values over 0. 90 for estimation of chickpea mechanical properties based on moisture content and physical properties.

Low stability in vegetable oils has been a quality problem. On the other hand the stability of vegetable oils depends on the composition of fatty acids especially oleic and linoleic acids. The aim of this study is finding one or more optimum ratio of the mixture of sunflower and canola oils that have good stability as well as suitable amount of essential fatty acids. The other aim is survey of dependence of stability to the amount of fatty acids in the mixture of sunflower and canola oils. In this study 7 samples of deodorized (and without any synthetic antioxidant) oils were prepared from several ratios of sunflower and canola mixtures. Metrohm rancimat was employed to evaluate the stability of the samples at 110°c. Fatty acids composition was determined with GC and peroxide، iodine value and refractive index at 40◦c be measured. There was a strong straight linear correlation between stability and the amount of oleic acid (r=0. 988، P-Value=0) but there was a straight reverse correlation between stability and the amount of linoleic acid (r= -0. 988، P-Value=0). Results showed that the canola oil in spite of its higher linolenic acid، had higher stability than sunflower oil. Between the amount of canola oil in mixture (with sunflower oil) and iodine value (r=-1، P-Value=0) and refractive index (r=-1، P-Value=0) there were reverse correlation. Results demonstrated that sunflower oil، in spite of its lower linolenic acid، had very lower stability than canola oil. The reason may be that sunflower oil has high content of linoleic acid، while canola oil has high content of oleic acid. With the considering the results، it is recommended that canola oil can be added to sunflower oil to increase its stability and nutritional values. Moreover two formulas «70% canola oil+ 30% sunflower oil» and «50% canola oil+ 50% sunflower oil» proposed as suitable blends.

Histamine is one of the biogenic amines which are produced as a result of enzymatic activity of spoilage agent bacteria. As tuna fish family posses a lot of free tissue histidine، they are susceptible of causing histaminic poisonings. In this study 88 samples of tuna fish cans were tested by ELISA method. the obtained results showed that 44. 3 percent of them contained higher amount of histamine than the permitted limit (50 ppm). Also it became specified that the tuna fish cans produced in southern states، had higher amounts of histamine in comparison to the products of northern and Central regions. Moreover، it was indicated that the newly made cans comparing to the cans that were nearly expired، contained lower histamine levels.