فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال یکم شماره 4 (زمستان 1391)

Generally speaking, the beneficial effects of polyunsaturated fatty acids (PUFA) on health and prevention of diseases have already been demonstrated. However, there is still a gap between the practical consumption of oily fish and the recommended daily intake of PUFAs. As a result, it seems that a rational approach to achieve the needed value is the enrichment of food products where this process may have a significant effect on their tastes. Therefore, in this research the capability of ultrasound (intensity up to 100%) for enrichment of Doogh with PUFAs as well as its influence on rheological and sensorial properties were evaluated. Our results showed that ultrasound was able to homogenize and stabilize ω-3 fatty acid enriched Doogh. Furthermore, the highest sensorial acceptability was seen in Doogh containing 0.25% fish oil. In addition, the most appropriate rheological model for samples containing up to 1% fish oil without thermal treatment and one with thermal pasteurization were Power law and Sisco models, respectively.

The object of this study was to evaluate the influence of the different concentrations of wall materials (maltodextrin, MDX, dextrose equivalent 16.5-19.5 and polyvinylpyrrolidone, PVP40) on the microencapsulated effective compounds of saffron (crocin, picrocrocin and safranal) by means of spray drying method. At the first step, the frozen dried aqueous extract of saffron’s effective compounds was prepared. Then, the solutions of 5, 10 and 15 percent of PVP and MDX containing 250 mg of freeze dried aqueous saffron extract were prepared. Afterwards, the prepared solutions were dried with spray dryer. At first the characteristics of microcapsules such as the color, aroma and flavor yield of microencapsulation, microstructure and particle size were tested, then the release speed of effective compounds at 52.89±0.22 humidity condition during 45 days of storage were evaluated. The results showed that the crocin content in microcapsules prepared with MDX, saffranal and picrocrocin content in microcapsules prepared with PVP were at the highest. The saffron’s effective compounds decreased with increasing wall concentrations. Microcapsules had spherical shape and nearly smooth surface and also microcapsules containing MDX as a wall material produced larger particles rather than microcapsules which were containing PVP. In addition, PVP 5%- as a wall material- contained the most effective compounds of saffron after 45 days storage.

Biopolymer-based nanocomplexes could be produced by electrostatic interactions between opposite-charge-groups on two types of biopolymers. In this research, the production method and properties of the kappa carageenan-caseinate based nanocomplex were investigated. The particle sizes of carageenan-caseinate complexes were vigorously dependent to pH and biopolymers concentrations and optimum level was observed for both of these factors. The sizes of the smallest particles were 74 and 75 nanometers which were obtained at pH=4.9 and concentrations of 1% caseinate-0.03% carageenan and 0.5% caseinate-0.02% carageenan, respectively. Reduction of pH from 5.3 to 5.1, caused decrease of particle size in all samples and continuing pH reduction to 4.9 caused more reduction of particle size at low concentration of caseinate. The zeta potential data showed that the amount of negative charges in complexes were higher than sum of charges in both biopolymers. All pure and complex samples showed Newtonian behavior and increasing both biopolymer concentrations enhanced viscosity of complex.

In recent years the increase in milk production worldwide on one hand and reduction in natural sources of "rennin" on the other, has resulted in significant decrease in rennin-produced cheese. In this research, it was attempted to clone the caprin prochymosin gene in the lactococcus lactis. If succeeded, the results of this work would allow production of cheese without the need for adding exogenous rennin or low quality fungal enzymes. The prochymosin gene which had been previously cloned in pET plasmid in E. coli BL21 was amplified by PCR and was then isolated from the agar gel, ligated to plasmid PTZ and cloned in E. coli GM. The prochymosin gene was cut by enzyme and ligated to L. lactis plasmid PNG and cloned in E. coli MC1061. The plasmid then isolated from E. coli MC1061 and transferred to L. lactis NZ9000 and recombinant cloned were sequenced.

Saffron is one of the most valuable crops on the Earth. The production rate of this plant is increasing in recent years. Saffron flower storing and processing is difficult. This study was performed to study physical, qualitative properties of Saffron flowers and to create a new field to export the cut flowers. Saffron flowers were packed at modified atmosphere packaging in polymer pouches (Polyethylene- polyamide and low density Polyethylene) with a gas combined of CO2–50%, O2–5%, and N2–45%. Sample and Control were kept at two temperatures 0 and 15˚c for 15 days. Every three days the concentrations of oxygen and carbon dioxide, the yield of product, physical properties of fresh stigma and chemical properties of dried stigma were measured. The existence of E. coli and enumeration of yeasts and moulds also were done. The results showed that low density polyethylene polymer pouches maintained the physical and quality properties of Saffron flowers better than Polyethylene polyamide pouches. Storage at 0˚c kept the flowers better than 15˚c. There were no evidences for E. coli growth in the samples.

The aim of this study was to evaluate the effects of xanthan, alginate, CMC and thawing properties on "Finger Fish" quality. Different gums added to pre-dust, to compare these effects and moreover thawing in air and microwave to compare with deep fat frying. Results depicted no significant differences in WHC and ash content (P>0.05). Types of added gums and thawing procedures had significant effects on crust adhesion (P<0.05). Effects of gum, thawing method and interactions on moisture were significant (P<0.05). Fat content of "Finger Fish" just affected by pre-dust gum type (P<0.05). Control fried group showed the highest and alginate-air group showed the lowest product yield (P<0.05). Gum type and thawing method had significant effects on L*, a* and b* value (P<0.05). Control group had the highest sensorial scores. Overall results showed common frying is the best in frozen "Finger Fish" thawing method and adding mixture of gums and flour into pre-dust has negative effects on final quality yield.