فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال چهارم شماره 2 (تابستان 1394)

In this study, effect of gender, muscle type (biceps femoris (BF) and longissimus thoracis (LT)) and storage time (14 days) on the proteolytic pattern of camel meat myofibrillar proteins was investigated using SDS-PAGE. Heavy chain myosin (MHC) and actin changed little during postmortem aging of muscles. Proteolysis intensity of MHC in female camels was significantly more than male ones (p<0.05). Degradation of C-protein was influenced by storage time, gender and muscle type (p<0.05). α-actinin was proteolyzed by catepsins at the second week of aging, and its breakdown was more pronounced in BF than LT muscle (p<0.05). Principal degradation of desmin occurred at the first week of storage. Troponin-T was proteolyzed by about 80% up to 5 days of storage, and muscle type and aging time significantly affected its proteolysis. The30 kDapolypeptideas a main product of Troponin-T degradation began to appear 24 h postmortem, and its band intensity increased significantly during 14 days of storage (p 0.05). In conclusion, storage time was the most important factor affecting degradation of myofibrillar proteins during storage at 4oC. Also, muscle type was a main factor at proteolysis of desmin cytoskeletal protein and some regulating proteins (α-actinin and Troponin-T).

Microbial growth and lipid peroxidation are primary factors of meat spoilage during refrigerated storage. Rosemary Boiss, locally known as Tashenadri, has been extensively used as a medicinal plant in Iran. In this study, the effects of Rosmarinus officinalis aqueous extract on quality and shelf life of chicken during chilled storage were investigated. Chicken samples were treated with aqueous extract of 1%، 3% and 5% R. officinalis, and then stored at 4 οC for 5 days. The control and the treated chicken samples were analyzed periodically for Microbial (Total count, staph aureus, Coliforms), chemical (pH, PV) and sensory characteristics. The results indicated that incorporation of R. officinalis water extract on chicken fillets caused the delay of lipid peroxidation and microbial spoilage. In this respect, the sample supplemented with 3% aqueous extract was more effective compared with the 1% and 5% in extending the shelf life of chicken fillets (P < 0. 05). It was concluded that the effect of R. officinalis extract on chicken samples kept their good quality characteristics and extended the shelf life during refrigerated storage, which was supported by the results of Microbial, chemical and sensory evaluation analyses.

One of the sugar beet compounds is α- amino azote which causes an increase in the amount of molasses produced. Therefore, the effect of beets size (in 4 levels; large, medium, small and mixed) obtained from three different regions as well as the height of storage (in 4 levels; floor of silo, 1 meter height, 3 meter height, 5 meter height) on the amount of α- amino azote in silos of Shirvan sugar factory during 18 days of storage was investigated. One of the effective factors on increasing of α- amino azote is conditions of storage in silos. The results showed that maximum increasing of α- amino azote during period of storage (18 days), belong to small sugar beets with 23.09 to 29.7 percent and minimum increasing of α- amino azote belong to large sugar beets with 11.83 to 18.65 percent. Further, the results showed that minimum increase of α- amino azote belonged to large sugar beets that were stored in surface of silos (5 meter height) with 10.91 to 11.21 percent and maximum increase of α- amino azote belonged to samples that were stored in middle levels of silos (3 meter height) with 20.32 to 33.95 percent.

Chubak extract having emulsification ability because of the presence of saponin and hydrocolloid components. The purpose of the current research is utilizing this extract ability to improve the quality of a kind of cake using Chubak alone and in combination with mono and diglyceride (E471) emulsifiers at three levels including 0, 0.5 and 1%. The effect of these additives was carried out by evaluating physiochemical and rheological properties of batter, and physical and sensorial properties of the cake. The results revealed that extract addition led to a decrease in specific gravity and increase in batter viscosity, and also an increase in L* index of crust and crumb, specific volume, porosity, moisture content, sensory characteristic score of texture and chewiness of cake and a decrease in cake firmness as it had a more effective role than E471. The similar results were obtained in utilizing E471 but it was preferred to Chubak extract in staling retardation during storage. Applying these two additives, in combination with each other enhanced the product quality which confirmed synergistic effect of emulsifiers. Practically, emulsifier mixture containing 1% chubak extract and 0.5% E471 was recognized as the best choice.

The purpose of this study was to investigate the effects of replacing milk powder with soy flour on the chemical characteristics, texture, particle size distribution and whiteness index of chocolate products. Treatments consisted of two refining times (105 and 135 min) and replacement of milk powder with soy flour at four levels (zero, 33.33, 66.66 and 100%). Results showed that by replacing milk powder with soy flour, moisture content of samples placed below 1.5%, ash and pH values ranged between 1.59 to 1.71% and 7.59 to 7.67, respectively. Particle size and hardness of samples significantly increased with the increase of the replacement level in both refining times, (P <0.05). Generally, extending storage time increased the whiteness index of samples in all replacement levels and both refining times.

The aim of this study was to investigate the effects of process conditions as well as ultrasound and microwave pretreatments on shrinkage of potato strips during deep-fat frying process. Ultrasound pretreatment was performed at frequencies of 28 and 40 kHz and microwave pretreatment was conducted at powers of 3 and 6 W/g on the potato slices. Then, the frying process was done at 150, 170 and 190°C for 1, 2, 3 and 4 min. According to the results, ultrasound pretreatment significantly reduced the shrinkage of potato strips. However, microwave pretreatment resulted in a significant increase in the samples shrinkage. In addition, frying time as an important process factor had a significant effect on shrinkage; such that by increasing time, shrinkage was increased. Moreover, the results showed that temperature effect on shrinkage is not significant. Furthermore, six models were presented in order to predict shrinkage considering the process conditions and for the models constants, multivariate models were obtained based on multivariate regression analysis as a function of process conditions (ultrasound frequency, microwave power and process temperature).