مجله علوم و صنایع غذایی ایران
سال سوم شماره 1 (پیاپی 7، بهار 1385)

The white cheese has high percentage of fat، (saturated and cholesterol) which is not desirable from human health point of view. The aim of this study was to produce low cholesterol white cheese (Feta) by the substitution of milk fat with sunflower oil (S. O) and determine its effects on the chemical، microbial and sensory parameters of the white cheese. For this S. O (1. 5، 2. 5 and 3. 5 percent) and monoglyceried stearat as emulsifier (5percent) were added to the milk containing (0. 05، 1 and 2 percent fat). The chemical، microbial and sensory tests were done on the samples. The fatty acids profile and the cholesterol were also determined (GC). The results showed that by addition of the S. O، cholesterol and saturated fatty acids (SFAs) were reduced and the percent of unsaturated fatty acids (USFAs) increased significantly (p<0. 05). In cheese samples with 1. 5، 2. 5 and 3. 5 percents of S. O، the amount of cholesterol reduced from 115. 1 to 66. 2، 29. 1 and 18. 8 milligrams respectively and the percents of the reduction of SFAs were 43. 2، 30. 2 and 16. 7 milligrams. The amounts of the USFAs increased significantly (p<0. 05) in compare with the control. In sensory evaluation tests the samples with 1. 5 and 2. 5 percents of S. O preferred in acceptance by panels. The samples with 3. 5 percent S. O had significant differences (P<0. 05) in sensory properties with the other samples. The ratio of 1:2. 5 (milk fat: S. O) was the proper substitution ratio which on that the amount of cholesterol and SFAs were reduced about 59 and 75 percents in the samples with the 29. 1 and 30. 2 milligram cholesterol and SFAs to compare with the control and the percent of USFAs increased from 27. 3 to 68. 3.

Some physico-chemical characteristics of Iranian linseed oil (Linum usitatissimum) such as oil content (44. 25%)، refractive index (1. 47)، peroxide (7. 21meqO2/Kg Oil)، iodine (170. 67gI2/100g Oil)، acid (3. 10mgNaOH/g Oil) and saponification (191. 73mgKOH/g Oil) values and fatty acid profile (C:، C18:0، C18:1، C18:2، C18:3) were studied. For preservation of ω-3 ingredients، the linseed oil that containing 43. 18% of ω-3 fatty acid، were kept in frozen condition (nitrogen atmosphere and -30 º C temperatures) and its peroxide value was determined after 0، 7، 30، 60 and 90 days. Statistical analysis showed significant difference (p<5%) average amount of peroxide value only in first 7 days of storage time and its increase (8. 30%) conformed to international standard.

The Effects of Partial Substitution of NaCl by KCl on Physicochemical، Sensory، Rheologyical Properties of Iranian White Cheese. Four trails of different mixture of Iranian white cheese with the ratios of NaCl/KCl: 1. 50% NaCl+ 1. 50%KCl، A; 1. 00% NaCl+ 2. 00% KCl، B; 0. 75% NaCl + 2. 25% KCl، C; and D as a control with 3. 00% NaCl were treated by dry salting to produce low salt cheese. The quality properties such as composition (moisture content، fat، total nitrogen with dry basis، water soluble nitrogen)، sensory properties (flavor and body texture)، and textural characteristics (force to fracture) were measured. The treatments exhibited no significant (P>0. 05) difference in the composition of cheese (moisture، fat، total nitrogen and water soluble nitrogen) after aging period. All treatments exhibited significant difference in sensory (flavor and body texture) properties. Textural properties (force to fracture) after 30 days aging showed that there was no significant (P>0. 05) difference between treatments A and D.

Malnutrition of children specially during weaning is one of the most important problems in developing countries such as Iran. So studying about supplementary and weaning foods is one of the important priorities. Considering the scientific reports show effects of germination on the nutritional improvement of cereals and legumes. This study was conducted on the weaning food production، mixed of germinated wheat and lentil powder to evaluate its physical and chemical properties in the National Nutrition and Food Technology Research Institute in year 2000. The search method was experimental and data collection was done by observation and measurement technique. At first two samples of wheat and lentil powder and germinated wheat and lentil powder with ratio of 89 to 11 as a proper ratio for supplying essential amino acids، were prepared and chemical composition of protein، fat، carbohydrate، ash، fiber and energy were measured. For physical experiment 12 samples of wheat and lentil powder and germinated wheat and lentil powder with ratios of 15%، 20%، 25%، 30%، 40%، and 50% mixed with water and their viscosity were measured. The result of chemical experiments showed that the percent of protein، ash and fiber of germinated sample was higher than regular sample but this difference was significant (P<0. 003) only for fiber. The measured viscosity indicated that it decreases significantly during germination. The proper viscosity of supplementary food was acceptable for gruel of wheat and lentil with ratio of 15% and for germinated sample 40% (less than 3000 cps). It means that for preparation of 100ml of baby food، it needs 15gr ungerminated and 40gr germinated flour respectively. So weaning food prepared by germinated flour has a higher nutritional values. (More than 2. 5 times). This study showed that use of germinated wheat and lentil flour as a proper base in weaning food formulation can be recommended because of their higher nutritional values.

There are several methods for calculating surface area of agricultural and food materials which have been used since long time ago. Along with the progress in computer science، image processing has been considered as a method that can be used to quantify the apparent characteristics of food and agricultural materials and to substitute human vision. In this research، a digital image processing method has been adopted for surface area calculation. the efficiency of this method was compared with the three customary methods، namely، using Area Measuring System (AMS)، planimeter method، and gravimetric method. Three experiments were devised using different tgpes of samples. Results showed that under all circumstances، the image processing method was no less accurate than the other methods. Moreover، its accuracy was independent of the operator accuracy and skill. The AMS was considerably faster than the other methods. The image processing method stood in the third place after the planimeter method where the time difference between them was less than five seconds.

Effect of fa contet of milk (2. 7%، 5%، 7% and 9%) on the growth and metabolic activity of starter cultures during fermentation of concentrated yoghurt (23% total solid)، was studied. Sensory assessment of yoghurt samples were also obtained. The characteristics that was measured during fermentation include: PH، acidity، count of starter bacteria (stereptococcus thermophilus and Lactobacillus bulgaricus)، and the characteristics that measured in final product were sensory properties. The experiments were done in three replications. Statistical evaluation showed that increase in fat content of milk، had no significant effect on PH but resulted decreasing of acidity of samples. Addition of fat content from 2. 7% upto 9% decreased acidity from 0. 97% to 0. 78%. with increasing in fat content from 2. 7% upto 9% count of stereptococcus thermophilus decreased from 391×106 cfu/ml to 279×106 cfu/ml where fat content had no significant effect on growth of Lactobacillus bulgaricus. Addition of fat content did not influenced the sensory acceptability of final product.

Regarding the increasing usage of pesticides to a broad variety of crops in Iran، and the importance of public concerns about possible health risks from pesticide residues، chlorinated pesticide residues in vegetables were determined in National Nutrition & Food Technology Research Institute in 2005. Thirty samples (melon، maskmelon، watermelon) were evaluated by an descriptive method. Sample extraction was carried out with ethyl acetate، and the extracts were cleaned up by high performance gel permeation chromatography. Pesticide residues were identified and quantified using gas chromatography ion trap mass spectrometry detector. Recoveries of chlorinated pesticides were within a range from 95-178%. Detection limit of pesticide residues were from 0. 01 to 0. 05 mgkg-1. The data demonstrated that the samples analysed did not contain residues of the monitored pesticides above the accepted maximum residue limit (MRL) as adapted by the FAO/WHO Codex Alimentarius Commission. This method proves to be successful in analyzing pesticides in vegetables and provides reliable and accurate results.

Little would be gained by discussing the nutritive value of bread in human diet. Fortification of bread with protein especially whey powder has been the center of attention in many countries. In this study Hamburger dough''s containing 0. 5، 1، 1. 5، 2، 2. 5، 3، 4. 5 and 7. 5 percent whey powder were Prepared. Chemical composition of whey powder and wheat flour was measured and also dough rheological properties were evaluated by ICC and AACC methods. Regarding rheological results، treatments contained 3 and 7. 5% whey powder were prepared. Crust color، crumb texture، flavor and volume of breads were evaluated by ten expert and trained panelists using a 0-9 point scale. Overall acceptability of breads was ranked by Phisher and Yaths method. The effect of whey powder on the staling rate of bread was evaluated by scoring test. Development time and resistant of doughs containing 1. 5% and 7. 5% whey powder was increased. Valorimetric value of dough with 7. 5% whey powder was higher than other treatments. Addition of whey powder increased the elasticity of dough''s and improved the volume and quality of breads. The result of sensory analysis indicated that crust color، crumb texture، flavor and volume of Hamburger bread containing 3% whey powder achieved highest score and the rank of this treatment concerning the overall acceptability was highest. From staling rate point of view mean scores of samples contained 3% and 7. 5% whey powder were greater than control. Regarding the chemical، rheological and sensory characteristics، Hamburger bread contained 3% whey powder was considered the best.