Prediction of lamb tenderness using combined quality parameters and meat surface characteristics

The objectives of the present study were: to investigate the predictability of cooked lamb tenderness from textural parameters extracted from lamb chops images using GLRM and GLDM techniques. To study the combined effects of texture features, marbling and ultimate pH on the prediction models

The role of metmyoglobin reducing activity in the maintenance of fresh meat colour

The oxidation state of myoglobin is a major factor in fresh red meat colour and is a result of net oxidation/ reduction processes occurring in the meat. However, the lack of association between metmyolgobin reducing activity (MetMbRA) and colour stability has lead to uncertainty over its role in post-mortem meat. Also, there are conflicting reports on the level of MetMbRA in meat during storage. Therefore, it was decided to investigate the role and the potential of MetMbRA in the maintenance of the colour of fresh meat. This involved a series of experiments to test whether any manipulation in colour, colour stability or MetMbRA would be linked to each other. Initially, the characteristics of MetMbRA in ovine longissimus were determined, and the effects of pre-rigor temperature (5°C to 35°C range), pre-slaughter stress and electrical stimulation on MetMbRA, colour and colour stability of ovine longissimus were investigated. MetMbRA was negatively affected by incubation temperatures above 30°C, but colour and colour stability were little affected at 24 h post-mortem and after 2 weeks of vacuum storage at 2°C. Neither pre-slaughter stress nor electrical stimulation affected MetMbRA or colour parameters. MetMbRA was not correlated with colour or colour stability. The results of that study indicated that MetMbRA was not the primary determinant of colour or colour stability of ovine longissimus muscle. Secondly, the effect of antioxidants on oxidative processes and MetMbRA in beef patties were investigated in two experiments. In the first experiment colour, colour stability, TBA values and MetMb reducing activity were measured during storage at 2°C of raw beef patties treated with four antioxidants (resveratrol, carnosine, quercetin and rutin) at two concentrations (110µmol/kg meat and 550 µmol/kg meat. In the second experiment the application of these antioxidants in solution was tested. The storage period and antioxidant treatment affected colour, colour stability and TBA values. The colour-stabilising effect of the antioxidants was in the following order resveratrol> quercetin> rutin> carnosine. The performance of resveratrol was affected by the method of application. Resveratrol gave the highest protective effect against lipid peroxidation. Carnosine acted as a pro-oxidant under the specified experimental conditions. MetMb reducing activity remained relatively stable during storage. It was concluded that pH, antioxidant concentration and method of antioxidant application could affect the potencies of the antioxidants in meat systems. MetMb reducing activity was not correlated with storage time, colour parameters, MetMb (%) or lipid oxidation. Also, it was concluded that the lack of NADH and not the loss of MetMb enzymatic activity was the factor limiting the MetMb reducing activity in beef patties and, consequently, the factor dictating the colour and colour stability of beef patties. Thirdly, the presence of MetMbRA in the myofibrillar fraction of muscle extracts was investigated as a possible reason for the observed increase of MetMb reducing activity in aged meat. The relationship between muscle MetMb reducing activities and meat colour parameters were investigated in a beef pattie system. NADH-dependent, MetMb reducing activity was found in the particulate fraction of meat following sedimentation of a meat homogenate at 35000 g. The presence of MetMbRA in the myofibrils (MMRA), defined as the activity in the sediment after centrifugation of a meat homogenate at 2000 g, was confirmed. The myofibrillar fraction contained 63% of the total MetMb reducing activity available in the meat. The particulate MetMb reducing activity (PMRA) in beef patties was found to be a good indicator of the total MetMbRA in meat. Different correlation between MetMb reducing activities and colour were obtained when beef patties were made of fresh meat (maximum 4 days post-mortem) and 5 weeks vacuum packed meat during normal cold display. Finally, a cause-effect study was designed to clarify the involvement of MetMb reducing activities in the preservation of the colour of fresh meat utilizing the differing effects of ZnCl₂ and CaCl₂ on meat colour. Pre-rigor water and ZnCl₂ infusions improved the colour and colour stability of ovine LD muscle. CaCl₂ infusion decreased the colour of the muscle. The effects of water, ZnCl₂ and CaCl₂ on colour seem to be due to their effects on the oxidative processes in meat, decreasing the pigment's concentration and altering the physical state of the meat. The data suggests that MetMb reducing activities (especially myofibrillar MetMbRA) may be contributing to the oxidation of lipid and meat pigment. In all the studied models, MetMbRA was not correlated to colour and colour stability of fresh meat. Thus MetMbRA is not an important factor for fresh meat colour

Manipulating the functionality of grape seeds products through reflective mulching and wine fermentation

Poster presentation of research carried out to investigate the effect of reflective mulching and wine fermentation on the fatty acids and the phenolics profiles of grape seed

Characterization of phenolic compounds in wine lees

The effect of vinification techniques on phenolic compounds and antioxidant activity of wine lees are poorly understood. The present study investigated the antioxidant activity of white and red wine lees generated at early fermentation and during aging. In this study, the total phenol content (TPC), total tannin content (TTC), mean degree of polymerization (mDP), and antioxidant activities of five white and eight red wine lees samples from different vinification backgrounds were determined. The results showed that vinification techniques had a significant (p 35 mg Trolox/g FDM) (PN: Pinot noir lees; FDM: Freeze-dried Material). This study indicates that tannin is one of the major phenolic compounds available in wine lees that can be useful in human and animal health applications

Upgrading the utilization of brassica wastes: Physicochemical properties and sensory evaluation of fermented brassica stalks

The potential to utilize brassica harvest residue and processing waste to add-value and /or to eliminate environmental concerns through fermentation was investigated. Some physicochemical properties (moisture, protein, ash, acid detergent fibre, vitamin C, total phenolic and amino acids contents, acidity and shear and compression forces) for broccoli and cauliflower stalks before and after fermentation were measured. Considerable vitamin C and total phenolics concentrations were found in fresh broccoli and cauliflower stalks. Fermentation decreased (P < 0.001) vitamin C concentration to about 55% of that found in fresh stalks of broccoli and cauliflower and decreased (P < 0.001) total phenolics concentrations (by 15% and 28% for broccoli and cauliflower, respectively). The results from the sensory analysis indicated that the fermented broccoli and cauliflower stalks may be successful as condiment products for consumers familiar with fermented products

In vitro digestion of red deer (Cervus elaphus) and cow (Bos taurus) milk

The aim of this study was to compare the digestion of milk proteins from deer and cow milk using in vitro digestion and to quantify the production of peptides using the O-phthaldialdehyde assay. Deer milk contained on average 8.8 ± 0.13% protein which is twice the levels found in cow milk (4.1 ± 0.02%). Deer and cow milk were digested in two steps; imitating both the human stomach (Pepsin, pH 2.5, 30 min) and the duodenum (Corolase PP, pH 7.5, 30 min). The degradation patterns of the milk proteins were visualized by SDS-PAGE and quantified using ImageJ software. Peptide production was significantly higher in deer milk than cow milk (P< 0.05). The commercial proteolytic enzymes degraded milk protein from deer more rapidly than those from cow. Deer casein was completely digested at 40 min of digestion (10 min into duodenum digestion) where as 14% of the casein was still present in cow milk. The digestibility of α-lactalbumin and immunoglobulin were also higher in deer milk than cow milk. However, β-lactoglobulin from both species appeared to be resistant to both gastric and duodenal digestion. This study shows that deer milk proteins were more digestible and produced more peptides than protein from cow milk. The bioactive functions of deer peptides are currently under investigation

Conjugated Linoleic Acid and Cholesterol Oxidative Products Generated in Hot Boned Beef Semimembranosus Muscle as Affected by Rigor Temperature, Ageing and Display Time

The present study investigated the effect of processing parameters comprising rigor temperature, ageing and display time on conjugated linoleic acid (CLA) concentrations, stability and the development of cholesterol oxidation products in hot boned beef semimembranosus muscles. Meat samples, having attained rigor mortis at 5 &deg;C and 25 &deg;C, were vacuum packed and aged for 7 and 14 days and then displayed under aerobic conditions for 7 days at 4 &deg;C. Lipid was extracted at each time interval then 1H NMR and GC-FID were used for CLA quantification. The cholesterol oxidation products (COPs) were separated from lipids via column chromatography and derivatized for GC-FID. The CLA content was not affected by the rigor temperature, ageing and display time (p &gt; 0.05). The cholesterol oxidative stability was not affected by rigor temperature (p &gt; 0.05) but was affected by ageing and display time (p &lt; 0.05). The COPs, 7&alpha;- and 7&beta;-hydroxycholesterol, and 7-ketocholesterol were positively identified and their quantities increased with ageing and display time (p &lt; 0.05). These results demonstrate that the production of COPs in semimembranosus muscle was significantly altered by the ageing and display time parameters but not by the rigor temperature used in this study

The effect of the supplementation of a diet low in calcium and phosphorus with either sheep milk or cow milk on the physical and mechanical characteristics of bone using a rat model

This study assessed the effect of cow milk (CM) and sheep milk (SM) consumption on the micro-structure, mechanical function, and mineral composition of rat femora in a male weanling rat model. Male weanling rats were fed a basal diet with a 50% reduction in calcium and phosphorus content (low Ca/P-diet) supplemented with either SM or CM. Rats were fed for 28 days, after which the femora were harvested and stored. The femora were analyzed by μ-CT, three-point bending, and inductively coupled plasma–mass spectrometry (ICP-MS). The addition of either milk to the low Ca/P-diet significantly increased (p < 0.05) trabecular bone volume, trabecular bone surface density, trabecular number, cortical bone volume, and maximum force, when compared to rats that consumed only the low Ca/P-diet. The consumption of either milk resulted in a significant decrease (p < 0.05) in trabecular pattern factor, and cortical bone surface to volume ratio when compared to rats that consumed only the low Ca/P-diet. The results were achieved with a lower consumption of SM compared to that of CM (p < 0.05). This work indicates that SM and CM can help overcome the effects on bone of a restriction in calcium and phosphorus intake

Effect of Dietary Protein and Processing on Gut Microbiota—A Systematic Review

The effect of diet on the composition of gut microbiota and the consequent impact on disease risk have been of expanding interest. The present review focuses on current insights of changes associated with dietary protein-induced gut microbial populations and examines their potential roles in the metabolism, health, and disease of animals. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol was used, and 29 highly relevant articles were obtained, which included 6 mouse studies, 7 pig studies, 15 rat studies, and 1 in vitro study. Analysis of these studies indicated that several factors, such as protein source, protein content, dietary composition (such as carbohydrate content), glycation of protein, processing factors, and protein oxidation, affect the digestibility and bioavailability of dietary proteins. These factors can influence protein fermentation, absorption, and functional properties in the gut and, consequently, impact the composition of gut microbiota and affect human health. While gut microbiota can release metabolites that can affect host physiology either positively or negatively, the selection of quality of protein and suitable food processing conditions are important to have a positive effect of dietary protein on gut microbiota and human health