Performing Department
Nutritional Sciences
Non Technical Summary
The Protein Digestibility Corrected Amino Acid Score (PDCAAS) has been used for more than 20 years to evaluate protein quality in human nutrition. However, this method has limitations because it is based on the total tract digestibility of crude protein (CP) and it is assumed that all amino acids (AA) have the same digestibility as CP. It is, however, recognized that digestibility of AA is most correctly determined at the end of the small intestine (the "ileum") because AA are absorbed only from the small intestine and because hindgut fermentation can affect fecal AA excretion. Therefore, ileal digestibility is a more accurate estimate of AA bioavailability than total tract digestibility in both humans and pigs. In addition, the digestibility of CP is not representative of the digestibility of all AA. Instead, individual digestibility values for each AA need to be used. As a consequence, FAO now recommends a new AA evaluation procedure called "Digestible Indispensable Amino Acid Score (DIAAS)". To calculate DIAAS, it is necessary that ileal AA digestibility values are generated and the pig has been recognized as the best animal model for estimating AA digestibility in humans. FAO also recommends that DIAAS values be generated for all proteins used in human nutrition, which will enable nutritionists to determine the quality of protein in meals fed to humans and ensure deficiencies of AA are avoided. There is, however, a lack of information about DIAAS values in proteins used in human nutrition. Research in our laboratory has determined DIAAS in eight cereal grainsand results of this research clearly demonstrate that cereal grains do not provide digestible AA in quantities that meet the requirement for AA by children or lactating women. It is, therefore, necessary that additional sources of AA are provided, and pork protein is a readily available source of protein in many countries in the world. In the recent FAO reportit is also clearly stated that DIAAS values for all food proteins need to be generated and specifically, there is a need to generate DIAAS values for meat products. Therefore, research characterizing DIAAS values in raw and processed pork loin will fill a void in our understanding of the nutritional value of food proteins.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Due to the importance of amino acid nutrition in humans it is imperative that knowledge about AA digestibility is generated because that will allow formulation of diets that can alleviate AA malnutrition specifically in children and lactating women. To do that, it is necessary to prepare meals that provide all AA in the required quantities, but that is not possible unless DIAAS values for the individual food proteins are known. The first step in overcoming AA malnutrition in humans, therefore, is to generate DIAAS values in food proteins. Because of the lack of information in this area, the objectives of this research are to 1) characterize the AA concentration and DIAAS value in raw pork loin and 2) determine the effect of different processing (i.e., roasting, frying, or grilling) on AA concentrations and DIAAS values in pork loin. The data generated from this research will be used to formulate diets for humans based on cereal grains and pork loin that meet the requirement for AA. It is currently not possible to formulate such diets, but with the results of the present research and our previously published data for cereal grains, it will for the first time be possible to calculate DIAAS values for a meal rather than for individual food proteins.
Project Methods
Pork loins will be sourced from commercial sources by the Meat Science Lab and divided into 4 batches. Pork loins will be from pigs fed a common industry diet so composition of test loins will be representative of loins purchased by consumers. One batch will be ground, vacuum packaged and then frozen to provide raw pork loins. The three cooking methods will be roasting, frying and grilled and in either method, loins will be prepared at a temperature of 145oF.Four diets will be based on each of the 4 batches of pork loin (i.e., raw, roasted, fried, or grilled) as the sole source of AA and fed to 10 ileal cannulated barrows with ten replicates per treatment. Ileal digesta will be collected from all animals and analyzed for AA. Values for the standardized ileal digestibility of AA will be calculated for each diet and the concentration of digestible AA (g/kg) in each ingredient will be calculated. The DIAAS ratio will be calculated using a published equation.