Effects of pre-rigor injection of sodium citrate or acetate, or post-rigor injection of phosphate plus salt, on post-mortem glycolysis, ph decline, and pork quality attributes

Swine research, 2005 is known as Swine day, 2005Forty pork carcass sides were assigned to one of four treatments: pre-rigor citrate (CIT) or acetate (ACE) injection, post-rigor phosphate plus salt (PHOS) injection, and noninjected control (CON). Loins in 20 sides were injected 50 min post-mortem with 4% solutions of CIT or ACE to approximately 110% of projected loin weights, and 10 PHOS-treated loins were injected at 24 h postmortem to 106.6% with a 4.4% PHOS plus 2.2% salt solution. Although CIT increased pH (P<0.05), neither CIT nor ACE altered (P>0.05) glycolytic metabolite concentrations. The pH increase in CIT-injected muscle was most likely due to its buffering ability rather than glycolytic inhibition. Citrate improved tenderness without the detrimental effects on color or flavor found with PHOS plus salt, but neither CIT nor ACE altered glycolytic metabolites or improved firmness, wetness, or fresh visual color over CON. Poor flavor attributes of the ACE treatment will discourage its use as an ingredient for pork enhancement solutions

Effects of oral administration or feeding of sodium citrate or acetate to pigs on post-mortem glycolysis, pH decline, and pork quality attributes

Swine research, 2005 is known as Swine day, 2005Previous studies have shown that citrate has the potential to inhibit phosphofructokinase (PFK), a key enzyme in post-mortem glycolysis. The objective of our study was to determine the effects of oral administration and feeding of citrate or acetate to pigs on post-mortem glycolysis, pH, and pork quality attributes. In Experiment 1, citrate, acetate, or water was orally administered to 30 pigs 45 min before stunning (electric plus captive bolt). In Experiment 2, citrate or acetate was fed to 30 gilts in 454 g of feed 60 min before stunning. Ante-mortem treatment had no effect (P > 0.05) on muscle pH or post mortem concentrations of glycolytic metabolites: glucose- 6 phosphate, fructose-6 phosphate, fructose-1,6 bisphosphate, glyceraldehyde-3 phosphate, dihydroxyacetone phosphate, or lactate. Minor, but inconsistent, differences in quality attributes were found in longissimus chops and inside and outside semimembranosus quality attributes among treatments (P>0.05). The reason for the lack of PFK inhibition is not known. Glycolytic-metabolite data indicate that PFK was a main regulatory enzyme in post-mortem muscle

Effects of oral administration of sodium citrate or acetate to pigs on blood parameters, postmortem glycolysis, muscle pH decline, and quality attributes of pork

The objective of this study was to determine the effects of oral administration of sodium citrate (CIT) or acetate (ACE) to pigs on blood parameters, postmortem glycolysis, pH decline, and quality attributes of pork. Previous studies have shown that CIT has the potential to inhibit phosphofructokinase (PFK), a key enzyme in postmortem muscle glycolysis. In Exp. 1, CIT, ACE, or water was orally administered (0.75 g/kg of BW) to 24 pigs. After a 30-min rest, pigs were exercised, and blood samples were taken at 45 and 75 min after oral treatment. Citrate and ACE tended (P = 0.08) to increase blood pH and increased (P = 0.02) bicarbonate levels immediately after exercise. After a 30-min rest, blood pH of pigs administered ACE tended (P = 0.09) to remain higher, whereas blood pH of CIT-treated pigs was similar to that of control pigs. Bicarbonate levels in ACE- and CIT-treated pigs were still greater (P 0.10) on muscle pH or postmortem concentrations of the glycolytic metabolites of glucose-6 phosphate, fructose-6 phosphate, fructose-1,6 bisphosphate, glyceraldehyde-3 phosphate, dihydroxyacetone phosphate, or lactate. Minor, but inconsistent, differences in quality attributes were found in LM chops, and no differences in quality attributes were found between control and CIT- or ACE-treated pigs for inside and outside semimembranosus muscles (P > 0.10). There was no significant inhibition of the PFK enzyme by orally administered CIT or ACE; however, the PFK glycolytic metabolite data analysis indicated that PFK was a main regulatory enzyme in postmortem muscle

Low carbohydrate diets and performance

Athletes are continually searching for means to optimize their performance. Within the past 20 years, athletes and scientists have reported and/or observed that consuming a carbohydrate restricted diet may improve performance. The original theories explaining the purported benefits centered on the fact that fat oxidation increases, thereby "sparing" muscle glycogen. More recent concepts that explain the plausibility of the ergogenicity of low carbohydrate, or high fat, diets on exercise performance pertain to an effect similar to altitude training. We and others have observed that, while fat oxidation may be increased, the ability to maintain high intensity exercise (e.g., above the lactate threshold) seems to be compromised or at least indifferent compared to when more carbohydrate was consumed. That said, clinical studies clearly demonstrate that ad-libitum low carbohydrate diets elicit greater decreases in body weight and fat than energy equivalent low fat diets, especially over a short duration. Thus, while low carbohydrate and high fat diets appear detrimental or indifferent relative to performance, they may be a faster means to achieve a more competitive body composition

Investigation of the effect of high dairy diet on body mass index and body fat in overweight and obese children

OBJECTIVE To investigate whether an increase in dairy food consumption improves the changes in BMI and adiposity in children on an energy restricted diet. METHODS Overweight and obese children (n = 120, age: 12-18 y, BMI: 27-40 kg/m2) were randomized to receive a calorie restricted diet providing a 500 kcal/d deficit from total energy expenditure and two (n = 40), three (n = 40) or four (n = 40) servings of dairy products/day. Anthropometric measurements in addition to serum hs-CRP and lipid profile were measured at baseline and after 12 weeks. RESULTS Among the 96 children who completed the study, significant reductions in overall BMI, BMI z-score, weight, total body fat percentage and total body fat mass were observed (p 0.05). Overall waist/hip ratio, Serum vitamin D and lipid profile did not change significantly (p > 0.05) apart from a significant increase in HDL-cholesterol (p 0.05). CONCLUSION Increased intake of dairy products does not lead to an augmented change in BMI, weight and body fat in overweight and obese children beyond what is achieved by calorie restriction