Functionalization of Non-interesterified Mixtures of Fully Hydrogenated Fats Using Shear Processing

Abstract

This paper explores the functionalization of mixtures of fully hydrogenated soybean oil (FHSO) and soybean oil (SO) by crystallization under specific shear and temperatures fields. FHSO was blended with SO at mass ratios of 40:60 and 45:55 and crystallized statically, under laminar shear (LS) at 30 s−1 and 240 s−1, and in a scraped surface heat exchanger (SSHE). The nano- and meso-scales were affected differently upon crystallization in a SSHE and LS cell. A decrease or no change was observed in meso-crystal sizes, meanwhile longer nano-platelets were observed after shearing. Rheological measurements demonstrated that the storage modulus (G′) and yield stress (σ*) of the fats were significantly reduced (from 35 to 90 %) after shear. Moreover, G′ and σ* of samples crystallized in a SSHE were lower than those of samples crystallized under LS; an effect related to a higher degree of crystal breakage and mechanical working. Direct and inverse relationships were observed between the mechanical properties and crystal sizes at the meso- and nano-scale respectively, suggesting a closer connection between the nano-scale and the macroscopic and functional properties of the system. Crystallization under shear induced a significant decrease in the oil binding capacity of the blends, compared to static conditions. Although we achieved mechanical properties of a functional fat material with both crystallizers; LS processing at a rate of 30 s−1 yielded more desirable oil loss values than rates of 240 s−1 and SSHE processing. Our findings demonstrate that the problem of functionalization of fully hydrogenated fats can be approached using simple shear processing.