Processing of Dairy Products Can Affect the Digestible Indispensable Amino Acid Score (DIAAS): An In Vivo Study in Bama Minipigs.

BACKGROUND

During manufacturing, different applied processes can potentially alter macro- and microstructures of milk proteins, which eventually affect the digestibility and the digestible indispensable amino acid score (DIAAS).

OBJECTIVES

We aimed to investigate the effects of different processes, including heating and fermentation, on the ileal digestibility of amino acids (AA) and DIAAS in dairy products.

METHODS

Six dairy products were produced under different processing conditions. Seven ileal cannulated Bama minipig (initial body weight: 20.0 ± 0.8 kg) were assigned to a 7 × 6 incomplete Latin square design, which incorporated 7 diets (6 dairy products and 1 nitrogen-free diet) and 6 7-d periods. Ileal digesta were collected for 9 h (from 08:00 to 17:00) on days 6 and 7 of each period. The content of crude protein (CP) and AA was determined. True ileal digestibility (TID) and DIAAS were calculated. One-way analysis of variance was used to evaluate the significant differences.

RESULTS

The TID of CP was 97.0% ± 1.6%, 98.7% ± 1.8%, and 100.7% ± 0.5% (mean ± standard error of the mean) for raw milk (RM), pasteurized milk (PM), and high temperature treated milk (HTM). The TID of methionine was lower (P = 0.050) for the pasteurized yogurt with pectin addition (PYP, 97.6% ± 0.4%) compared with that in the nontreated yogurt (NTY, 99.5% ± 0.5%) and pasteurized yogurt (PY, 99.5% ± 0.3%). Regarding DIAAS results, the quality of proteins in the studied products was predominantly classified as "excellent" and partially as "good." For individuals older than 3 y, the DIAAS were 112, 123, 104, 110, 110, and 120 for RM, PM, HTM, NTY, PY, and PYP.

CONCLUSIONS

Although different processes could alter the values of TID and DIAAS, the protein quality in the studied dairy products still remained as high. Milk protein from each of the dairy products can be highly utilizable if ingested alone.