Individual and combined effect of pH and whey proteins on lactose crystallization

Yanira I. Sánchez-García, Néstor Gutiérrez-Méndez, Raúl E. Orozco-Mena, Victor H. Ramos-Sánchez, Martha Y. Leal-Ramos

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Lactose is recovered by crystallization from cheese whey that is a by-product of cheesemaking. The whey used for the recovery of lactose usually has a residual content of protein that alters the crystallization of lactose. In addition, the pH of whey may fluctuate depending on the cheese variety. However, there is little information on how the pH modifies the effect that whey proteins have on lactose crystallization. Accordingly, this work aimed to evaluate the individual and combined effect of whey proteins and pH on the kinetics of crystallization, the crystal size distribution and the crystallinity of lactose. The addition of whey proteins in lactose solutions (25% v/v) modified the process of lactose crystallization. However, the effect that whey proteins had on lactose crystallization heavily depended on the pH. The number of crystals per milliliter as well as the growth and size distribution of crystals was the most affected with the changes in pH (pHs of 7, 5.5 and 4) and the addition of whey proteins (0 and 0.63%). All the treatment produced mostly α-lactose monohydrated but some treatments also generated crystals of β-lactose (pH 5.5, 0% of proteins). Amorphous lactose was observed mainly in lactose solutions adjusted at pH 7 and added with whey proteins. This particular treatment also incorporated the highest amount of protein into the lattice of lactose crystals. The results of this work highlight the importance of controlling the pH of lactose crystallization, especially if there is a presence of whey proteins.

Original languageEnglish (US)
Pages (from-to)455-461
Number of pages7
JournalFood Research International
Volume116
DOIs
StatePublished - Feb 2019
Externally publishedYes

Keywords

  • Amorphous lactose
  • Crystal size distribution
  • Lactose crystals
  • pH of crystallization
  • Serum proteins

ASJC Scopus subject areas

  • Food Science

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