STLO, AGROCAMPUS OUEST, INRA, UMR 1253, 35000 Rennes, France.
Department of Food Technology, Universidade Federal de Viçosa (UFV), Avenida P. H. Rolfs, Viçosa, MG 36570-000, Brazil.
Food Res Int. 2019 Feb;116:175-183. doi: 10.1016/j.foodres.2018.08.009. Epub 2018 Aug 3.
When dairy powders are produced, the mineral fraction undergoes strong modifications during the vacuum concentration step, leading to the fouling of falling film evaporators. The objective of this study was to determine the nature of the deposits formed during the vacuum concentration of two fouling and highly mineralized products: hydrochloric acid whey and lactic acid whey. These products mainly differ in terms of their mineral composition: lactic acid whey contains a high level of lactic acid and traces of citrate, whereas hydrochloric acid whey contains citrate and no lactic acid. Concentrates at different concentration factors were produced using a pilot-scale falling film evaporator. The compositions of the fouling deposits as well as the precipitates present in the concentrates were deduced from the analytical determination of the composition of the concentrates and their respective diffusible phases. The behavior of the mineral fraction of both acid wheys during concentration was shown to be very different. In the case of hydrochloric acid whey, experimental results suggested a deposition of calcium and citrate ions in the evaporator as well as their precipitation in the highly concentrated products. On the contrary, neither mineral deposition nor precipitation occurred during the concentration of lactic acid whey. This study underlined the key role of citrate ions in the fouling of evaporators during the concentration of hydrochloric acid wheys.
当乳制品粉末生产时，矿物质成分在真空浓缩步骤中会发生强烈的变化，导致降膜蒸发器结垢。本研究的目的是确定在两种结垢且高度矿化产品（盐酸乳清和乳酸乳清）的真空浓缩过程中形成的沉积物的性质。这些产品主要在矿物质成分方面有所不同：乳酸乳清含有高水平的乳酸和微量柠檬酸，而盐酸乳清含有柠檬酸但没有乳酸。使用中试规模的降膜蒸发器生产不同浓缩倍数的浓缩物。通过分析浓缩物及其各自可扩散相的组成来推断结垢沉积物的组成和存在的沉淀物。结果表明，两种酸乳清的矿物质成分在浓缩过程中的行为非常不同。在盐酸乳清的情况下，实验结果表明钙和柠檬酸离子在蒸发器中沉积，以及它们在高浓度产品中的沉淀。相反，在乳酸乳清的浓缩过程中既没有发生矿物质沉积也没有发生沉淀。这项研究强调了柠檬酸离子在盐酸乳清浓缩过程中对蒸发器结垢的关键作用。
