Journal of food science and technology
Year:2006 | Volume:3 | Issue:2|Papers Count:9

The aim of this research was to study the effects of whey protein concentrate (WPC) and casein hydrolysate (CH) on chemical (pH and titratable acidity), physical (consistency and syneresis) and sensory properties of yogurt containing probiotic bacteria. Reconstituted skim milk at 10% total solids was fortified with 1 and 2% of WPC, CH and blend of them (WPC to CH ratios of 1:1). Reconstituted skim milks were made with 11 and 12% total solids as control. Bioyogurts were prepared with commercial probiotic starter culture (Lactobacillus acidophilus, Bifidobacterium sp., Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). Fermentation was stopped at pH=4.6 and samples stored at 4oC for 21 days. Addition of WPC resulted in the highest pH value and the lowest titratable acidity. Acidity values of supplemented bioyogurt samples increased between 0.12 - 0.19% during 21 days of storage. Moreovere syneresis of these yogurts was lower and their consistency was higher than control. Bioyogurts containing WPC had the lowest syneresis and samples containing CH or WPC had the highest consistency. With regards to total acceptability, the best samples were bioyogurts supplemented with WPC and blend of WPC and CH.

In this study, 70 ice cream shops, in the city of Shiraz, were randomly selected and ranked into 3 grades (1 to 3) according to the apparent hygienic condition of the shops and their workers. Seventy traditional Iranian ice cream samples were collected and total bacterial count, enterobacteriacae count, Staphylococcus aurous coagulase positive count, E. coli, Salmonella as well as acidity, milk solids non fat (MSNF), fat and total solids were examined, in accordance with the Iran national standard. Nearly all samples failed for total bacterial count whereas, only 92.6% of samples failed for enterobacteriacae count, 36.6% for staphylococcus count, 20% for E. coli contamination, 7.8% for acidity, 80% for MSNF, 70% for fat content and 1.5% for dry matter. Salmonella was not detected in any sample.Staphylococcal count was high in 50% of grade 3 and 16.7% of grade 1 shops and the difference was significant between the two types of shops. In other experiments, no significant difference was observed among the various grades of shops. This study showed that traditional Iranian ice cream produced in Shiraz had low hygienic qualities and potentially high risk for consumers and there is no significant correlation between apparent hygienic condition of shops and their workers and the hygienic quality of their products. In addition, the nutritional value of this product, as a dairy source, may be undesirable.

The seeds of ten pomegranate (punica granatum L.) cultivars were analyzed for their physicochemical and oil properties. Also mineral elements such as Zn, Cu, Fe, Mn, Mg, Na and K were determined by ICP atomic emission spectroscopy. The highest quantities of mineral belonged to Mg, K and Na.Also, the quantities of ash and protein in pomegranate seeds were 1.81-2.35 % and 6.63- 12.95,% respectively. The average contents of refractometer, unsaponifiable, saponification, iodine, peroxide, acidity, moisture and volatile matter were the ranges 1.50-1.51, 1.16-1.63, 181.3-187.9 mgKOH/g, 165-179.4, 0.3-07 meqO2/kg oil, 0.25-0.4 % and 0.10-0.19 %, respectively.

Spinach is one of the most important leafy vegetables of chenopodiaceae family. This plant is native to Iran and has valuable nutrients. In this research mineral element content (like potassium, calcium, magnesium, phosphorous, iron, cupper, zinc), protein, total fiber, total fat, oxalic acid, phenolic compounds and fatty acids of seven Iranian spinach cultivars (Arak, Khorram Abad, Shirvan, Bojnourd, Karaj, Varamin and Lahijan) were analyzed and compared. Results showed that Arak cultivar had the highest amount of potassium, calcium and copper; Lahijan cultivar had the highest amount of magnesium and protein, Varamin cultivar had the highest amount of phosphorous, zinc, fiber and fat, Khorram Abad cultvar had the highest amount of iron. The lowest amount of oxalic acid was determined in Karaj and Lahijan cultivars (53.8 mg/ 100 g of fresh weight). Phenolic compounds had significant difference and cultivar Shirvan had the the highest amount of these compounds (110 mg Tanic Acid/gdw). The highest percentage of linolenic acid (w3) and linoleic acid (w6) were belonged to the Arak and Lahijan cultivars, respectively. Therefore Iranian spinach cultivars have considerable amount of minerals, fiber, protein, phenolic compounds, essential fatty acids (linolenic acid (w3) and linoleic acid (w6) and should be used in diet programs.

Aerobic mesophilic counts (AMC), were obtained by swabbing 25 cm2 areas at seven site (neck, brisket, leg, flank, rib set, forehand, hind quarter) on beef carcasses, after each Slaughter process (skinning, evisceration, splitting, trimming and primary washing, final washing). Reduction in counts at individual sites were observed after trimming and primary washing (about 0.2 log cfu.cm-2) and final washing (about 0.2 log cfu.cm-2 ) similarly. Increases in counts at most outside sites were observed after skinning, (about 2.5 - 3.5 log cfu.cm-2) and after evisceration, at brisket (about 1 log cfu.cm-2) and forehand (about 0.5 log cfu.cm-2) respectively. The incidence of Salmonella and E. coli on beef carcasses were also obtained by swabbing the outside surfaces of 12 carcasses after each stage.A large number of increases in positive samples for E.coli and Salmonella were observed after skinning and after evisceration (16.6% and 9.2% respectively). After final washing Salmonella and E. coli were detected on 11.9% and 7.1% of samples. The impact of beef slaughter processes on carcass microbiology and their potential use as critical control points (CCPs) during beef production are discussed.

Minimum inhibitory concentrations (MIC) of some essential oils and citric acid were determined against two micro-organisms associated with spoilage of orange juice (Saccharomyces cervisiae and Leuconostoc mesenteroids) and against four unidentified microorganisms isolated from citrus surface and spoiled orange juice. MIC for limonene were obtained less than 5% w/v aqueous against Saccharomyces cervisiae and Iso-2.Lianalool minimum inhibitory concentrations was less than 5% w/v aqueous for Leuconostoc mesenteroids. MIC for other microorganisms and essential oils and citric acid were determined more than 5 % w/v aqueous. Survivor Curve testing was conducted on 6 microorganisms.

Experimental infrared dryer was used to study the effect of rough rice temperature and air velocity on grain crack during infrared radiation and convection drying. Factorial experiment with Completely Randomize Block design was applied to the experiment at three temperature levels of 45, 60 and 75oC (equal to radiation intensities of 0.19, 0.39 and 0.58 W/cm2) and two inlet air velocity levels of 0.4 and 0.6 m/s. The result showed that the rough rice temperature (radiation intensity) and air velocity had significant effect on crack losses. Increasing the radiation intensity and decreasing air velocity caused to increase of crack percentage during drying of rough rice samples. The comparison of infrared and convectional drying method showed that grain cracks with infrared drying energy at 60 and 75oC (0.39 and 0.58 W/cm2) were less than that with convection drying at the same temperatures. But it did not have a significant difference at 45oC (0.19 W/cm2). The mathematical model relationship of grain crack percentage with rough rice temperature and air flow velocity was derived. Also the result show that the effect of rough rice temperature was more than air velocity on grain crack in infrared radiation drying.

Making and using dried products because of high losses of unprocessed product during transportation, economical benefits of grocery, special weather in Iran, good marketing etc. has been increased. In this research, kiwifruit slice favorite in two ripeness levels (stiffness 0.5 and 1.5), two cultivars (Monty and Hayward) and three moisture levels (15, 20 and 25 %wb) is evaluated by sensory evaluation. In this test sense qualities as color and appearance, chew ability, taste and flavor and general favorite are considered. Primary test in preparing kiwifruit slice showed that moisture contenttime curve during the first 7 hours is linear and after that it becomes exponential. Also the shortest time to dry is for Monty variety with more ripeness (0.5 kg) and the longest time refers to Hayward with less ripeness (1.5 kg). Results showed that in general the greatest score is dedicated to Hayward with more ripeness and moisture of 20 %. The least score is of Monty with less ripeness and moisture of 15%.Hayward variety due to better odor and flavor and more soluble sugar, has special advantage.It is concluded that Hayward variety with ripeness of 17% Brix index and moisture of 20% is the best option to make kiwifruit slice.