​Biochemical and Physicochemical Characteristics in Different Skeletal Muscles of Sheep Hind Limb

Background: High variation in meat quality has been reported between animals and within muscles of same animals. An understanding of these variations is a pivotal step to design strategies for better utilization of such meat while producing high quality meat to consumers. The current study was aimed to unravel biochemical and physico-chemical profile of sheep hind limb. Methods: The sheep hind limb was procured from traditionally slaughtered sheep immediately after exsanguination. The Vastus lateralis (VL), Gluteo biceps femoris (GBF), Gluteomedius (GM), Longissimus thoracis et lumborum (LTL), Psoas major (PM) and Semitendinosus (ST) muscles were separated from hot boned carcass of sheep. Each hot boned muscle was cut and analysed for biochemical and physico-chemical characteristics. Result: There was significant (p less than 0.05) variation in water holding capacity, protein extractability (Sarcoplasmic, myofibrillar and total), collagen content, collagen solubility and instrumental colour value among different skeletal muscles studied. Non-significant (p greater than 0.05) variations were found in parameters like pH, drip loss, myofibrillar fragmentation index, muscle fibre diameter and Warner Bratzler shear force values. The Gluteo biceps femoris muscle was found to have higher myoglobin; myofibrillar fragmentation index and Warner Bratzler shear force values with lowest protein extractability values. The collagen content in the Gluteo biceps femoris was significantly (p less than 0.05) higher with lowest collagen solubility (15.32%) as compared to other muscles.

Protein Extractability and Thermally Induced Gelation Properties of African Locust Bean Proteins (Parkia biglobosa Jacq. R.Br)

African locust bean (AfLB) protein isolates could be an interesting alternative to the use of soy as an ingredient for the development of new protein-rich products. From AfLB seed flour, the protein extractability yields by aqueous extraction were determined as a function of pH and ionic strength. Then thermally induced gelation of various protein suspensions relating to protein concentration was studied. The most critical factors affecting extractability were the pH and the presence of fat. As a function of the extraction process, the extraction yield of protein from AfLB flour ranged from 30 to 65%. Two major fractions of proteins detected in AfLB seeds were albumins and globulins, comprising four families: legume-like protein, vicilin-like proteins, convicilin, and albumins. The globulin isolate had the lowest solubility at pH 3.5-4 and the highest at pH 8-10. The solubility of albumin isolate was lightly affected by pH and ionic strength. At pH 7, the minimum protein concentration for thermal gel formation ranged from 55 to 120 g/L as function purified state of proteins. The less purified extract with a simpler process made it possible to obtain a gel needing a lower protein concentration. This last way seems promising to the development of new foods based on African locust bean flour.

Impact of Extraction Method on the Detection of Quality Biomarkers in Normal vs. DFD Meat

The objective of this work was to demonstrate how the extraction method affects the reliability of biomarker detection and how this detection depends on the biomarker location within the cell compartment. Different extraction methods were used to study the sarcoplasmic and myofibrillar fractions of the Longissimus thoracis et lumborum muscle of young bulls of the Asturiana de los Valles breed in two quality grades, standard (Control) or dark, firm, and dry (DFD) meat. Protein extractability and the expression of some of the main meat quality biomarkers—oxidative status (lipoperoxidation (LPO) and catalase activity (CAT)), proteome (SDS-PAGE electrophoretic pattern), and cell stress protein (Hsp70)—were analyzed. In the sarcoplasmic fraction, buffers containing Triton X-100 showed significantly higher protein extractability, LPO, and higher intensity of high-molecular-weight protein bands, whereas the TES buffer was more sensitive to distinguishing differences in the protein pattern between the Control and DFD meat. In the myofibrillar fraction, samples extracted with the lysis buffer showed significantly higher protein extractability, whereas samples extracted with the non-denaturing buffer showed higher results for LPO, CAT, and Hsp70, and higher-intensity bands in the electrophoretic pattern. These findings highlight the need for the careful selection of the extraction method used to analyze the different biomarkers considering their cellular location to adapt the extractive process.

Effects of preservation on protein extraction in four seaweed species

Using either freshly pulped or preserved seaweed biomass for the extraction of protein can have a great effect on the amount of protein that can be extracted. In this study, the effect of four preservation techniques (frozen, freeze-dried, and air-dried at 40 and 70 °C) on the protein extractability, measured as Kjeldahl nitrogen, of four seaweed species, Chondrus crispus (Rhodophyceae), Ascophyllum nodosum, Saccharina latissima (both Phaeophyceae) and Ulva lactuca (Chlorophyceae), was tested and compared with extracting freshly pulped biomass. The effect of preservation is species dependent: in all four seaweed species, a different treatment resulted in the highest protein extractability. The pellet (i.e., the non-dissolved biomass after extraction) was also analyzed as in most cases the largest part of the initial protein ended up in the pellet and not in the supernatant. Of the four species tested, freeze-dried A. nodosum yielded the highest overall protein extractability of 59.6% with a significantly increased protein content compared with the sample before extraction. For C. crispus extracting biomass air-dried at 40 °C gave the best results with a protein extractability of 50.4%. Preservation had little effect on the protein extraction for S. latissima; only air-drying at 70 °C decreased the yield significantly. Over 70% of the initial protein ended up in the pellet for all U. lactuca extractions while increasing the protein content significantly. Extracting freshly pulped U. lactuca resulted in a 78% increase in protein content in the pellet while still containing 84.5% of the total initial total protein. These results show the importance of the right choice when selecting a preservation method and seaweed species for protein extraction. Besides the extracted protein fraction, the remaining pellet also has the potential as a source with an increased protein content.

Proteomic Characterisation of Lupin (Lupinus angustifolius) Milk as Influenced by Extraction Techniques, Seed Coat and Cultivars

Lupin seeds are rich in proteins and other essential ingredients that can help to improve human health. The protein contents in both whole and split seeds of two lupin cultivars (Mandleup and PBA Jurien) were used to produce the lupin milk using the cheesecloth and centrifuge method. Proteins were extracted from the lupin milk using thiourea/urea solubilization. The proteins were separated by a two-dimensional polyacrylamide gel electrophoresis and then identified with mass spectrometry. A total of 230 protein spots were identified, 60 of which showed differential abundances. The cheesecloth separation showed protein extractability much better than that of the centrifuge method for both the cultivars. The results from this study could offer guidance for future comparative analysis and identification of lupin milk protein and provide effective separation technique to determine specific proteins in the cheese-making process.

Nutrient Composition and Protein Extractability of Oat Forage Harvested at Different Maturity Stages as Compared to Grain

<p>Two oat varieties (CDC Dancer and Lamont) were grown in fields. Plants were harvested at three key stages: seedling (Forage 1), mid-season (Forage 2), and full grain maturity. The mature plants were separated into stover (Forage 3) and Grain. There were differential changes among measured attributes during growth. From seeds to Forage 1, crude protein (CP) and ash contents increased several fold, beta-glucan decreased, starch disappeared, and oil content remained unchanged for both oat varieties examined. As plants grew, CP, ash, oil and beta-glucan decreased, but other carbohydrates increased significantly. The CP content in Forage 1 was 5–fold higher than Forage 3 and 2-fold higher than Grain. Most macro and micro-minerals in forage followed the same changing pattern as ash. Amino acid composition of forage differed significantly from that of Grain. When subjected to aqueous media with a wide range of pH, forage harvested at each stage as well as grain all had their unique protein extractability curves. For forage, the peak value (the maximum extraction) decreased with maturity. Yet, as observed for both varieties, Forage 1 had a peak value half of that from Grain. In conclusion, based on the results from this study, nutrient composition in oat forages harvested at an early stage can be comparable or even superior to oat grains but low protein extractability limits oat forage use as an alternative protein source for non-ruminants.</p>