Impact of Dietary Selenium on Meat Quality Juan Gomez-Basauri, Ph.D.
Meat Quality Characteristics Appearance Color Tenderness Texture Flavor Aroma
Purchasing Decision Color Oxidative Stability
Oxidative Rancidity/Oxidative Stability Temperature Metals Enzymes Lipid Oxidation PUFA s Light Microorganisms Chemicals Nutrient value Nutrient bioavailability Nutrient Stability Discoloration Drip losses Off flavors Toxic end products
The Tools? Low temperature Metal Chelation MAP Antioxidant
Antioxidant Systems
Natural vs. Synthetic
The Beneficial Role of Vitamin E There is fairly strong evidence
Effect of Feeding a Natural Antioxidant in Shelflife Stability 12 10 TBARS (umol/g) 8 6 4 2 Fed Aox, Further Process Stored w/o Aox (6 Mo) Stored w Aox (6 Mo) 0 Synthetic Preventox Antioxidants adapted fromvalenzuela et al., 2004
What are the opportunities to enhance the nutritional value of meat, milk, eggs?
Selenium Story
2001 Edens: Se part of Thioredoxin reductase (redox regulator) Today recognize Se needed for growth, reproduction, immunity Selenium Story Se Nutrient 1957 Schwarz & Foltz: Se essential trace mineral for mammals 1973 Rotruck: Se integral part of GSH-Px 1974 Cantor and Scott: Se supplementation shows response in poultry 1982 - Burk and Gregory: Se role as a transport protein 1991 - Ekholm et al., Se response in beef cattle 1992 Behne: Se part of 5 iodothyronine deiodinase
Inorganic vs. Organic The source of selenium plays an important role in terms of selenium effectiveness when the source is organic: either from naturally high selenium feeds (Lawler et al., 2004) or supplementation with selenium yeast (Edens, 1996, Mahan and Parret, 1996; Pehrson et al., 1999). Other studies also indicate that the source of selenium plays a role in terms of selenium effectiveness when the source is organic: either from naturally high selenium feeds (Lawler et al., 2004) or supplementation with selenium yeast (Edens, 1996, Mahan and Parret, 1996; Pehrson et al., 1999).
Inorganic vs. organic selenium Inorganic selenite is highly oxidized. In contrast, selenoamino acids in plants and useful in metabolism are very reduced. Oxidation state Compound (example) Most reduced Se -2 Selenomethionine Selenides Selenocysteine Se 0 Elemental Se Se +4 Na 2 SeO 3 (Na selenite) Most oxidized Se +6 Selenate ( Na 2 SeO 4 )
Inorganic Se is highly absorbed, but most is promptly excreted 3 fates of absorbed dietary selenium Organic Se Selenomethionine Inorganic Se Selenate Selenocysteine Selenite 1. Body protein synthesis (storage) Selenide H 2 Se 2. Excretion via kidney 3. Selenoprotein synthesis (GSH-Px, etc) Little dietary inorganic Se is stored in body proteins
How About Meat Quality?
Drip Loss
Seasonal and Selenium Source Effects on Breast Meat Drip Loss Drip Loss, % 5.2 5.1 5 4.9 4.8 4.7 4.6 4.5 4.4 Sodium Selenite Sel Plex a a 0.1 ppm 0.3 ppm Adapted from Edens, 1996
Effect of dietary selenium supplementation on drip loss for porcine longissimus dorsi muscle 12 10 Drip Loss (%) 8 6 4 Steaks Selenite Steaks Sel-Plex 2 0 24 48 72 120 Time Post-Mortem (h) p > 0.5
(adapted from Simek et al., 2002) Drip and fluid losses from vacuum packed meat and stored for 4 and 8 days Drip Loss Fluid Loss (%) 4 d (%) 8 d (%) Control 0.92 0.29a 0.69 7 d prior with Sel-Plex 1.17 0.45a 0.40 30 d prior with Sel-Plex 0.5 0.03b 0.65
Effects of dietary vitamin E and Se on some meat quality parameters Storage at 4 C 0 7 14 OMb TBARS OMb TBARS OMb TBARS Control 73.1 0.24 50.2 1.91 32.2 2.86 +E 79.3 0.11 61.3 0.38 52.5 0.65 +Se 69.6 0.28 51.1 1.71 38.6 2.34 +E+Se 71.6 0.09 62.1 0.19 54.0 0.28 adapted from O Grady O et al., 2001
Health Benefits Functional Meat Major dietary source of macronutrients such as protein Excellent source of micronutrients such as zinc, iron, selenium and copper, as well as the vitamins folic acid and B12
Selenium and Cancer 1970 s - Schrauzer, Shapiro, Frost, Shamberger, Se deficiency linked to the prevalence of cancer
Selenium status and cancer 46% 58% 64% 100 Relative risk, % 80 60 40 20 P<0.001 P=0.04 P<0.03 P<0.002 0 All cancers Lung Colorectal Prostate Clark et al., 1996 Selenium Placebo
Adequate Se and Vitamin E Mice that consumed a diet high in PUFA s (menhaden oil) showed severe cardiac muscle damage compared to control diets and diets adequate in Se and vitamin E when exposed to Coxsackie s virus (Beck et al., 1994).
What is the Future?
Selenopork
Branded Se- enriched milk An opportunity to enhance the nutrient value of milk
There is a Challenge
Take the opportunity to redefine our meat products