The effect of extended refrigerated storage on the physicochemical, structural, and microbial quality of sous vide cooked biceps femoris treated with ginger powder (zingibain).

The aim of the study was to investigate quality and shelf life of beef meat cooked under sous vide conditions then extended refrigerated storage for 10 weeks. Biceps femoris (n = 6) from six to seven year old cows were treated with 2 g/L ginger powder (GP) containing zingibain or control (no injection) and were then cooked in sous vide conditions at 65 °C for 1 h or 8 h. Cooked samples were evaluated for physicochemical (pH, total water content, cooking loss, Warner-Bratzler shear force (WBSF), texture profile analysis (TPA), L*, a*, b* properties and thiobarbituric acid reactive substance (TBARS)), microstructure (scanning electron microscopy) and microbiological (Brochothrix thermospacta, Clostridium perfringens, Lactic acid bacteria, Listeria monocytogenes, Salmonella spp, and yeasts and moulds) quality after vacuum packing, cooking, then refrigerated storage at 4 °C for 0, 2, 4, 8 or 10 weeks. Physicochemical parameters were improved by GP treatment (P < 0.05) while there was no effect of storage time on WBSF, TPA or microstructure. The microbial quality of sous vide cooked meat in refrigerated storage appeared to be four weeks and oxidation shelf life of the cooked meat was found to be two weeks under refrigerated storage.

Meat tenderness: advances in biology, biochemistry, molecular mechanisms and new technologies.

Meat tenderness is an important quality trait critical to consumer acceptance, and determines satisfaction, repeat purchase and willingness-to-pay premium prices. Recent advances in tenderness research from a variety of perspectives are presented. Our understanding of molecular factors influencing tenderization are discussed in relation to glycolysis, calcium release, protease activation, apoptosis and heat shock proteins, the use of proteomic analysis for monitoring changes, proteomic biomarkers and oxidative/nitrosative stress. Each of these structural, metabolic and molecular determinants of meat tenderness are then discussed in greater detail in relation to animal variation, postmortem influences, and changes during cooking, with a focus on recent advances. Innovations in postmortem technologies and enzymes for meat tenderization are discussed including their potential commercial application. Continued success of the meat industry relies on ongoing advances in our understanding, and in industry innovation. The recent advances in fundamental and applied research on meat tenderness in relation to the various sectors of the supply chain will enable such innovation.

Myosin sensitivity to thermal denaturation explains differences in water loss and shrinkage during cooking in muscles of distinct fibre types.

The effect of thermal protein denaturation on the structure and quality of muscles of different fibre types is not well understood. Unaged masseter (100% type I fibres) and cutaneous trunci (93% type II fibres) muscles (N = 10) were assessed for their characteristics, protein denaturation, cooking loss, Warner- Bratzler shear force (WBSF) and shrinkage after heating at 50 °C - 85 °C with a rate of 5 °C/ min. Raw masseter had a higher pH, collagen and water content, shorter sarcomere, comparable fibre diameter, and shorter and wider fragments upon homogenization, than cutaneous trunci. In cutaneous trunci, at 55 °C - 60 °C, the lower transition temperature of myosin and the greater cumulative enthalpy resulted in greater cooking loss in muscle cuboids, and greater transverse, longitudinal and volume shrinkage in fibres and fibre fragments, than in masseter. Protein denaturation explained 71% variability in fibre fragment volume and 58% in cooking loss of both muscles, as well as 47% variability in WBSF of masseter.

Thermal denaturation of proteins in the muscle fibre and connective tissue from bovine muscles composed of type I (masseter) or type II (cutaneous trunci) fibres: DSC and FTIR microspectroscopy study.

The changes in secondary structure of proteins with heating were characterised and compared for bovine masseter (fibre type I) and cutaneous trunci (fibre type II) muscles by Differential Scanning Calorimetry (DSC) and Fourier Transform InfraRed (FTIR) microspectroscopy. Heating led to a decrease in α- helices, and an increase in aggregated strands, random coils and aromatic side chains in the muscle fibres of both muscles. In the intramuscular connective tissue (IMCT) of both muscles, a decrease in α- helix, turn and unordered structures was complemented with an increase in aggregated strands. At temperatures < 60 °C, the greater thermal denaturation of proteins in cutaneous trunci than in masseter (FTIR), supported by a myosin associated peak at 55.8 °C for cutaneous trunci and no peak for masseter (DSC), indicates that myosin in type II fibres is more sensitive to thermal denaturation than myosin in type I fibres and this should be considered in thermal meat processing.

Ageing and cathepsin inhibition affect the shrinkage of fibre fragments of bovine semitendinosus, biceps femoris and psoas major during heating.

This study examines the effects of ageing (1, 14 days), cathepsin inhibition (No or Yes) and temperature (25-90 °C) on the shrinkage of fibre fragments from three bovine muscles (semitendinosus, biceps femoris and psoas major) during heating. Shrinkage was quantified using light microscopy images. Muscle fibres (except in psoas major) had greater transverse shrinkage, and less longitudinal shrinkage in aged than in unaged muscles at temperatures ≥60-75 °C. In addition, cathepsin inhibition during heating at ≥65-90 °C caused greater transverse shrinkage in semitendinosus fibres, and reduced longitudinal shrinkage for all muscles. At temperatures ≥75 °C, the longitudinal and transverse shrinkage of the fibres was correlated for all muscles. Ageing of biceps femoris increases volume shrinkage on a fibre level, and hence potentially cooking loss, while cathepsin activity in the semitendinosus reduces volume shrinkage. In conclusion, cathepsin activity and ageing influence the shrinkage that occurs during heating and these factors should be explored further to enable optimisation of thermal meat processing.

Muscle, Ageing and Temperature Influence the Changes in Texture, Cooking Loss and Shrinkage of Cooked Beef.

This study aimed to quantify the effect of muscle, ageing and cooking temperature on the texture, cooking loss and shrinkage of cooked beef. Cuboids from unaged (1 day post mortem) and aged (14 days post mortem) semitendinosus, biceps femoris and psoas major muscles, from both sides of five beef carcasses, were cooked at four different cooking temperatures (50, 60, 70 and 80 °C) for 30 min. and their Warner-Bratzler shear force (WBSF), cooking loss and shrinkage (longitudinal and transverse) were quantified. The WBSF was reduced by ageing in the muscles at the specific cooking temperatures: psoas major (cooked at 50, 60 and 80 °C), semitendinosus (70 and 80 °C) and biceps femoris (80 °C). The cooking loss was 3% greater in aged compared to unaged muscles. The longitudinal shrinkage was greatest in psoas major at 80 °C amongst the muscle types and it was reduced by ageing in psoas major (70 and 80 °C) and biceps femoris (80 °C). The transverse shrinkage was reduced by ageing only in biceps femoris, across all temperatures; and the diameter of homogenized fibre fragments from semitendinosus and biceps femoris was reduced more by cooking at 50 °C in unaged compared to aged condition. WBSF was related to transverse shrinkage, and cooking loss was related to longitudinal shrinkage. The effect of muscle type on the physical changes occurring during cooking of beef is dependent on ageing and cooking temperature.

The effect of barrier properties of polymeric films on the shelf-life of vacuum packaged fresh pork meat.

The aim of this study was to investigate the permeability properties of synthetic polymeric materials and their influence on the quality of packed chilled pork. Barrier properties of biaxially oriented polypropylene (BOPP) coated with acrylic/polyvinylidene chloride (BOPPAcPVDC) and biaxially oriented coextruded polypropylene (BOPPcoex), were tested on three gases: oxygen, carbon dioxide and nitrogen at different temperatures: 4 °C, 20 °C, 40 °C and 60 °C. Coefficients of permeability, diffusion and solubility were determined. The quality parameters of vacuum packed fresh chilled pork stored under controlled temperature over a 21-day period were evaluated with physico-chemical, sensory and microbiological analyses. Results showed that BOPPAcPVDC film provided better protection for fresh pork than BOPPcoex film in terms of physico-chemical, sensory and microbiological attributes, due to its greater barrier behaviour, with smaller permeance data (q) (0.98 to 324 cm3/m2 · d · bar) for BOPPAcPVDC, compared to BOPPcoex (227 to 6200 cm3/m2 · d · bar), in the temperature range from 4 °C to 60 °C (p < .001). The shelf life of fresh pork packed in this film was doubled, from 7 to 14 days.