nutritional and functional properties of whey and lactose

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NUTRITIONAL PROPERTIES OF WHEY PRODUCTS The composition of whey products varies considerably, depending on milk source and the manufacturing process involved. In general, whey is rich in proteins, lactose, minerals and vitamins. The proteins in milk and whey are complete and of exceptional quality. They contain, in varying amounts and in the right proportion, all the amino acids required by humans. They are also readily digestible and completely bio-available. Clearly, whey proteins are among the most valuable component of whey. In many cases, whey products are used for their nutritional benefits as they are a very cost-efficient source of protein, carbohydrate and minerals such as calcium. PROTEINS The proteins in whey are easily digested and contain all the essential amino acids in the proper proportions, and they rate as an excellent nutritional source. Using the Protein Digestibility-Corrected Amino Acid Scoring (PDCAAS) method, whey protein rates a value of 1.0 because it is highly digestible and it meets or exceeds the recommended amount of each essential amino acid. Using another method to measure protein quality—the Protein Efficiency Ratio (PER) value—whey also ranks high on the scale. The higher the PER value, the better the protein. Casein, the reference protein, has a PER value of 2.5. Proteins with a PER greater than 2.5 are considered to be quality proteins. Whey protein, with a PER greater than 3.0, is considered to be a nutritionally excellent protein. Figure 3 Essential amino acid profile of sweet whey proteins and nutritional requirements of selected groups (FAO/WHO) Essential Amino Acids Valine Tryptophan Threonine Phenylalanine.+Tyrosine Methionine.+Cystine Lysine Leucine 5 9 11 13 17 16 19 19 22 24 35 34 41 Virtually every amino acid present in sweet-type whey exceeds Food and Agriculture Organization/World Health Organization (FAO/WHO) nutritional intake recommendations, both for children aged 2 to 5 and for adults (see Figure 3). In many cases, for adults, whey proteins offer more than double the minimum FAO/WHO standards. 59 58 62 63 66 68 88 Whey Powder Child, 2-5 years Adult 103 Isoleucine 13 28 59 Histidine 20 19 16 0 20 40 60 mg/g Crude Protein 80 100 120 Source: Glass, L. and T.I. Hedrick. FAO/WHO. 1976 34 e34
Whey proteins compare favorably to many common proteins that have a PER of less than 2.5, including soya, peanuts, corn and wheat gluten (see Figure 4). These proteins have limited concentrations of certain essential amino acids. Because of whey protein’s balanced amino acid profile, whey products are excellent ingredients for protein fortification. By fortifying certain vegetable proteins with whey proteins, scientists have achieved PER values significantly greater than 2.5 and greater than the average of the PER values for the two proteins. In each blend, whey protein contributed no more than 50% of the total protein. VITAMINS The water soluble vitamins in milk remain in the serum and are collected with the whey. The concentration of vitamin C is reduced during processing, and whey is not considered a significant source of vitamin C. The concentration of other water soluble vitamins in sweet whey powder is presented in Table 4. Vitamins are large molecules and they are concentrated by ultrafiltration. Whey products will naturally fortify the thiamin, riboflavin, pantothenic acid, vitamin B 6 and vitamin B 12 content of foods. Suppliers can provide specific information on the vitamin contents of their whey products. Vitamin A is the most abundant fat soluble vitamin in milk. Vitamins A, D, E, and K are separated with the milk fat that is entrapped in the curd and separated with the whey cream. Figure 4 Protein Efficiency Ratios (PER) of Various Animal and Vegetable Proteins Table 4 Water Soluble Vitamin Content of Sweet Whey Powder Casein Whey Protein Sodium Caseinate Hen Egg Peanut Soya Corn 1.8 2.2 2.2 2.5 2.6 3.2 3.9 WHO Recommended Daily Intake* Sweet Whey Child Adult Powder Vitamin 1–3 years male Content/100g** Thiamin (B 1 ) 0.5mg 1.2mg 0.5mg Riboflavin (B 2 ) 0.8mg 1.8mg 2.2mg Niacin (PP) 9.0mg 19.8mg 1.3mg Pantothenic Acid 5.6mg Vitamin B 6 2.4µg Folic Acid 100.0µg 200.0µg 12.0µg Vitamin B 12 0.9µg 2.0µg 2.4µg Wheat Gluten 0.8 *World Health Organization. 1974. **Potosi and Orr. 1976. 0 1 2 PER 3 4 Source: Anon. 1972. e35 35
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