Mahsan Irajifar; Mohammad Javad Varidi; Mehdi Varidi; Younes Zahedi
Abstract
Introduction: Camel carcasses has lower fat content in comparison with cow, moreover, camel meat has relatively higher polyunsaturated fatty acids and lower cholesterol contents (Kadim et al., 2009a & 2006). However, calcium amount of camel meat is greater than that of cow, and its lower consumption ...
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Introduction: Camel carcasses has lower fat content in comparison with cow, moreover, camel meat has relatively higher polyunsaturated fatty acids and lower cholesterol contents (Kadim et al., 2009a & 2006). However, calcium amount of camel meat is greater than that of cow, and its lower consumption is partly related to this issue. With increasing demand of camel meat, more attention has been paid to the quality and chemical composition of it. Acid marinade can be used through the diffusion of the solution and its propagation over time as an extensive method to improve the meat tenderness (Yusop et al., 2010). Lactic acid is often used in the meat industry as an antimicrobial during carcass slaughter. In addition, lactic acid can improve meat tenderness (Hinkle et al., 2010). The aim of the present study was to determine the influence of lactic acid and sodium chloride on textural and sensory properties, also and proteolysis pattern of biceps femoris muscle of camel.
Materials and Methods: Six 4 to 7 years old camels were transported to the slaughterhouse in Mashhad (Iran). Slaughtering and dressing of camels were carried out according to Islamic methods. All chemicals and reagents in the experiments were of analytical grade and purchased from Merck and Sigma-Aldrich companies. Biceps femoris muscle was used as an experimental material, cutting into 2×2×5 cm3 pieces, and laid in lactic acid solutions (0, 0.5, 1, and 1.5% v/v, all accompanied with 2% w/v NaCl) at a ratio of 1 to 4 (meat to marination solution) within plastic bags. Marination process was carried out for 0, 24, 48, 72 h at 4 °C. The meats were then removed from the marinade and dried lightly. After that, moisture, ash, protein and fat contents of the meat were specified by AOAC (2002). Shear force was measured by TA.XT plus texture analyzer (Stable Micro Systems, UK) provided with a Warner-Bratzler shear force blade method in order to evaluation of meat tenderness (Byrne et al., 2000). Myofibrillar fragmentation index (MFI) was determined as described by zahedi et al. (1393). Sarcomere length was measured with the method of Botha et al. (2007). One-dimensional gel electrophoresis was determined as described by zahedi et al. (1393). Collagen content was specified by AOAC (1993). Sensory properties including color, texture, flavor, juiciness and overall acceptance were performed using a 5-point structured hedonic scale (Hoffman et al., 2006 & 2008). One-way analysis of variance (ANOVA) was used to determine the significant differences between treatments using SPSS software (version 19). Duncan’s multiple range test was used to compare the means.
Results and discussion: Acid concentration and marination time had a significant effect (p <0.05) on sarcomere length. It was likely due to the fact that the addition of acid led to increase in pure positive charges on myofibrils and cytoskeletal proteins. As a result, more repulsive forces were generated between the protein molecules of myofibrils. Eventually, myofibrils swelling caused distancing Z lines from one another, and increasing the sarcomere length (Ke et al., 2008). The results of analysis of variance showed that the concentration of lactic acid had a significant effect on MFI (p<0.05), and MFI value was less than zero at 0% concentration, however, it was non-significant in relation to the time (p> 0.05). The higher MFI values of the marinated samples may be due to the proteolysis of myofibrile proteins using D-cathepsins which activated at acidic pH (range 3-6). Meat samples marinated in the highest concentration for 72 h showed the lowest WBSF (p<0.05). The tenderising mechanism of acid marinades was believed to be including weakening of structures due to swelling of meat, increasing proteolysis by cathepsins, and conversion of collagen to gelatin at low pH during cooking (Berge et al., 2001; Offer & Knight, 1988). The retention time and acid concentration did not have a significant effect (p> 0.05) on the collagen amount of lactic acid treated samples. It was likely that low acid concentration, although affecting some of the parameters, is not suitable for degradation of connective tissue (Hinkle et al., 2010). Sensory analysis showed that tenderness of the samples marinated at with 1.5% acid received the highest score (p<0.05), which was consistent with the instrumental results. Acid concentration significantly affected (p<0.05) total acceptance of the samples. Higher levels of acid can be used for marinating without adversely affecting the consumer acceptance. Results from SDS-PAGE showed that number of seven bands on gels, on average, were belonged to intact proteins, and other bands were considered as peptides which resulted from proteins proteolysis, especially heavy proteins. Also, time had non-significant effect on band area of myosin heavy chain (p>0.05), while, acid concentration had a significant effect on the area of this protein (p<0.05). The band area of proteins C, α-actinin and actin proteins enhanced as a function of acid concentration and marination time (p<0.05).
In conclusion, we can claim that lactic acid and sodium chloride can be used as an effective acidic marination to improve biceps femoris muscle of camel meat. This method can be advice as a trick for tenderizing camel meat in household consumptions, restaurants and also meat industry, thereby increasing demand for camel meat in order to gain further healthy benefits of it.
Elham Eshaghabadi; Farajollah Shahriari; Mohammadreza Nassiry; Mohammad Reza Edalatian Dovom; Amin Mirshamsi
Abstract
Introduction: Bread is considered as one of the most important commodity which has provided human nutritional needs for several centuries. In recent decades, bread consumption has witnessed tremendous increase due to rising of other foods expenses. Cereal and bread industries has been always concerned ...
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Introduction: Bread is considered as one of the most important commodity which has provided human nutritional needs for several centuries. In recent decades, bread consumption has witnessed tremendous increase due to rising of other foods expenses. Cereal and bread industries has been always concerned about bread production in an industrial scale along with suitable shelf life, acceptable organoleptic properties and free from any chemical additives and preservatives. Among different methods such as addition of synthetic enzymes, gums, emulsifiers and improvers, sour dough has gained special attention besides shelf life enhancement and improvement of sensorial and nutritional features. The main role of sour dough has been prominent for fermentation and gas production in dough as a result of inclusion of Lactic Acid Bacteria (LAB) as a technology. Fluctuation of process parameters including temperature, dough yield and starter culture composition determine the sour dough quality. The main reason of sour dough application in wheat bread is flavor enhancement. Culture-based microbiological examinations have accompanied with some difficulties in accurate and precise identification of Lactobacilli. So, in recent years, in order to identify precisely, different molecular and PCR assays and gene sequencing have been applied. Thus, in present study, fragment of 253bp from 16 S rRNA gene in Lactobacillus plantarum was amplified with the help of PCR and sequenced in the next step. Also, comparison of nucleotide sequence of this region of traditional Lb. plantarum with nucleotide sequence of industrial starter (Germany) and sequences deposited in Gene Bank was evaluated.
Material and Methods: Sampling: According to sensory properties, sour dough samples were collected from Torbat e jam city and industrial starter sample (sour dough) was prepared from Buker Company, Germany.
Isolation and bio chemical analysis: Ten- fold serial dilutions of samples were prepared and cultured on MRS agar. Gram positive, catalase negative isolates were considered as presumptive LAB.
Molecular Identification: DNA of isolates were extracted according to the procedure of DNA extraction kit (Thermo, K721, USA). In order to amplify the 253 bp fragment of 16S rRNA in Lb. plantarum, specific primers were designed using Primer Premier 5. PCR was performed in Biometra Thermocycler (T- personal, Germany) in 36 cycles. In the following step, PCR products were sent to Macrogen Company for sequencing.
Bioinformatics analysis: Analysis of sequencing results was conducted with the aid of bioinformatics soft wares including CLC Main work bench, Chromas Lite 2.01, MEGA 5 and BioEdit. Phylogenetic tree was designed among different isolates using Neighbor-Joining method (bootstrap=1000) in MEGA 5 software. For determination of genetic distance, Create Pairwise comparison method was used in CLC Main workbench.
Results and Discussion: Quality and quantity of extracted DNA samples were confirmed by Gel electrophoresis. PCR and electrophoresis of PCR products confirmed and proved the accuracy and validity of amplified 253 bp fragment with intended primers. Comparison of Torbat and Germany nucleotide sequences demonstrated that two replacement mutations have been occurred including (A/C) and (T/C) in positions 182 and 205, respectively. These changes resulted in replacement of Histidine by Proline, and Glutamine by stop codon. Nucleotide content of 16S rRNA gene sequence in Lb. plantarum isolated from Torbat e Jam and Germany sour dough samples displayed both sequences contained 49.4% (G+C) and 50.6% (A+T). Phylogenetic results demonstrated that Lb. plantarum isolated from Torbat e Jam and Germany samples were classified in the same sub group. This implies the close phylogenetic relationship between these two lactobacilli. In order to identify Lb. plantarum, 16S rRNA gene was sequenced in sour dough samples of Germany and Belgium and phylogenetic tree showed that Lb. plantarum had the lowest genetic distance with Lb. pontis and highest one with Lb. sanfranciscensis and Lb. salivarius
