Heat Processing in Infant Formulas Induces Changes in Copper Tissue Levels in Suckling and Weanling Rats

Abstract

Aim: To assess the effects of dehydration, conventional in-bottle sterilization, and ultrahigh-temperature (UHT) sterilization, involved in the production of infant formulas, on the copper bioavailability in rats at two stages. Methods: Two-week-old suckling rats were fed a reconstituted powder (P1) and an in-bottle-sterilized liquid infant formula (SC1) in a drinking bottle for 7 days. Weanling rats were fed P1, SC1, another powder (P2), and a liquid UHT formula (UHT2) complemented with a standard rat diet. Intake, body weight, and percentage copper absorption were calculated, and whole-body, serum, liver, skin, and erythrocyte copper concentrations were determined. Results: Food intake, body weight, and copper intake were reduced in suckling rats consuming SC1, but the percentage copper absorption increased, and whole-body and tissue copper concentrations were unaffected, except for the erythrocyte copper concentration which was significantly higher as compared with pups fed P1. In weanling rats, the only difference observed was the significantly higher liver copper concentration in animals fed the diet containing P1 as compared with the diets containing SC1 and UHT2. Conclusions: Consuming the SC1 formula induced high erythrocyte copper levels in suckling rats, whereas the equivalent dehydrated formula (P1) induced elevated liver copper concentrations in weanling rats. This is associated with the different Maillard reaction products resulting from the processing of each infant formula and with the developmental stage of the animals.

The interaction of metal ions with Maillard reaction products in a lactose–glycine model system

“…Participation of metals in the Maillard reaction and their incorporation into intermediate products is closely related to the biological availability of mineral elements (Delgrado-Andrade, Seiquer, Nieto, & Navarro, 2004;Morales, Fernández-Fraguas, & Jiménez-Pérez, 2005;Sarria & Vaquero, 2001, 2006Seiquer, Valverde, Delgrado-Andrade, & Navarro, 2000;Whitelaw & Weaver, 1989) and the chemical damage caused to some essential amino acids (Leclere, Birlouez-Aragon, & Meli, 2002;Seifert, Krause, Gloe, & Henle, 2004). According to several authors, the amounts of soluble and dialyzable Zn and Fe in model solutions or thermally treated products decreased significantly due to the interaction of reducing sugars and amino acids.…”