Iranian Food Science and Technology Research Journal
Year:2008 | Volume:4 | Issue:1|Papers Count:10

In this study, a flexible package comprises of three layers, polyethylene (100m), aluminium foil (9m) and polyester (12m) was used for packaging blackcherry preserves. All packed preserves were kept up to three months at 4 different storage temperatures (4, 23, 35 and 40oC). Physicochemical, microbial and organoleptical properties of all trials were determined monthly. As a result, the average pH, oBx, acidity, Fe and Pb content were 3.99, 17.49, 0.25, 3.16ppm and 387.98ppb. All organoleptical properties of samples were acceptable. Temperature had statistically significant effect on the physicochemical and organoleptical properties of samples. The samples stored at 4 and 23oc were more acceptable due to their better quality. Flexible pouches have more advantages such as good colour and constant level of heavy metal as well as low cost and..

The objective of this study was to determine the effect of CO2 treatment on proteolysis, lipolysis and quality characteristics of refrigerated raw milk. Four treatments of raw milk were selected (controlled milk (milk without any special treatment) and milks treated with CO2 until pH=6.4, 6.2, 6). All experiments were triplicate. Samples were stored at 4oC for 10 days and were analyzed on 1, 5, 8, 10 day for chemical evaluations. Statistical evaluation of the effects of treatments was performed using of split plot experiment with randomized complete block design (RCBD). Statistical analysis, indicated that no significant proteolysis and lipolysis were observed during 10 days of storage using addition of CO2 to pH=6, 6.2 and an increase in CO2 concentration did further reduce proteolysis and lipolysis. The sensory panel did not detect significant difference between CO2 treated milks and fresh milk. The research revealed that the best treatment was using of CO2 to pH=6, although in the most cases there was no significant difference between pH 6.2 and 6.

The rock candy is the grown sucrose crystal which has been produced in Iran and India for the first time originally. In this process, the large sucrose crystals have been produced by cooling the supersaturated solution. The traditional processing has not changed up to now. Recently, many efforts were done to optimize it. The production of rock candy evaluated under cooled crystallization process. To increase the yield and the growth of sucrose crystals, the supersaturation and crystallization parameters should be optimized. Due to low efficacy in this procedure, sucrose crystals with dimensions less than 3 mm are usually produced by evaporating crystallizers. In this research, traditional production process of rock candy is studied by doing experiments at different phases in a traditional plant. According to the results, it takes more than 90 min to reach the suitable supersaturation, an temperature (112oC) and extra evaporation. So the invert sugar content, reach from 0.015 % in original sugar to 0.571 % in effluent (mother syrup). The produced rock candy has 0.553 % invert sugar. The pH of solution decreases from 7.3 to 5.2, the color increased from 70 (in primary sugar) to 1240 ICUMSA unit in the effluent and more than 250 Iu in produced rock candy (measurement in  l=420nm). The high color rate and invert sugar cause the effluent cannot be used in production process.

Stabilizers have been used to improve the texture of ice cream for several decades. They added it to ice cream to control ice and lactose crystal growth during hardening and storage, to give body and stiffness during freezing for air incorporation and to impart smoothness in body and texture. Nowadays, most of the industrial stabilizers are provided from abroad, so, extraction, determination of functional properties and study of the hydrocolloid components of Iranian local plants is seemed to be necessary. For this purpose, in two distinct production series, the carboxymethylcellulose and salep gums were replaced by Lallemantia royleana (Balangu) seed hydrocolloid in five levels (0, 25, 50, 75, and 100%). Some qualitative characteristics of ice cream such as viscosity, overrun, specific gravity and sensory properties were determined and compared with control. In sensory evaluation, intensity of coldness, firmness, viscosity, degree of smoothness, liquefying rate and total acceptance were studied. The use of Balangu hydrocolloid and its synergistic effect with carboxymethylcellulose and salep gums led to decrease in overrun, increase of viscosity and improve in sensory properties. Furthermore, this application has economical benefits.

In this paper, the effect of transmembarne pressure (TMP) at levels of 1, 1.75 & 2.5 bar, process temperature (T) at levels of 30 & 60oC and operation time (t) at levels of 15, 30, 45 & 60 minute on the permeate flux, sugar rejection, non-sugar rejection and fouling as membrane performance indexes investigated. Membrane system used in this research was ceramic tubular module and it had effective area and average pore diameter of 0.28 m2 and 0.2 mm, respectively. The results showed that the permeate flux at each levels of TMP and T decreased with increasing operation time. Increasing TMP at T=30oC led to decreasing the JP, but for T=60oC, the JP increased with increasing TMP. However, the flux values for T=30oC was higher than T=60oC at all TMP levels. In this research, it also observed that the fouling values at T=60oC were greater as compared to T=30oC at all TMP levels. Furthermore, in the best operation condition, the sugar and non-sugar rejections obtained -30% and 65%, respectively.

In this study the antimicrobial effects of essential oils from dill and coriander seeds on staphylococcus aureus, Escherichia coli O157:H7 and salmonella typhimuruim were investigated and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each essential oil were determinate. For this purpose 5 concentration of each essential oils (125, 250, 500, 1000, 2000 and 4000 ppm) were chosen. For microbial count, Broth Dilution Test with Mueller Hinton Agar and Broth were used. Results showed that Staphylococcus aureus had more susceptibility and Salmonella typhimuruim was the resistant one. Our results also showed that essential oil from coriander seed had more antimicrobial effect on the gram-negative bacteria. The essential oil from coriander seed had MIC and MBC equal to 1000ppm and the essential oil from dill seed had MIC equal to 500ppm and MBC equal to 1000 ppm against Staphylococcus aureus.

Regarding many disadvantages of traditional method to produce concentrated yoghurt, several attempts have been done for mechanization of process in industrial scale. Using membrane systems especially ultra filtration is one of these methods. In this survey, method to produce direct concentrated yoghurt, fresh milk was concentrated to 19% SNF by ultra filtration method then diluted to 13 and 16% SNF by adding skim milk. In these samples, Fat content was standardized to 5% and samples were incubated after inoculation with starter to reach acidity 1.6. Moreover the effect of adding calcium chloride in 0 and 0.01% levels was investigated. Results showed that characteristics such as incubation time, synersis, taste and texture score and adhesive force decreased by increasing SNF but firmness increased. Also adding calcium chloride didn’t have any significant effect on measured characteristics.