Molecular profiling of whey permeate reveals new insights into molecular affinities related to industrial unit operations during lactose production.

Lactose powder production from whey permeate generates various side-streams. Molecular profiling of these side-streams and lactose powder can help to detect minor compounds affecting lactose crystallization, lactose powder properties and document the composition of the underutilized side-streams. In this study, whey permeate, lactose powder and intermediate streams from trial lactose productions were analyzed using gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy. In total, 110 compounds were identified and 49 were quantified. Linking the molecular profiles to in-process steps revealed differential compositional attenuation by the unit operations. Small molecules (e.g. methanol) and a few larger molecules (e.g. fatty acids) permeated reverse osmosis membrane, while twenty-three compounds (e.g. hydroxypyruvic acid, malonic acid, gluconic acid and ribonic acid) co-crystallized with lactose and ended up in lactose power. These results help to better understand and control lactose powder production and highlights possibilities to develop new food ingredients.

Screening of non-protein nitrogen compounds in lactose refining streams from industrial whey permeate processing.

The NPN compounds from dairy processing side-streams are a promising source for new products. In this study, the NPN profile of lactose production samples was screened using GC-MS and 1H NMR spectroscopy. These analytical platforms allowed the identification of 35 NPN compounds including, amino acids and derivatives, amino alcohols, organic acids, and other classes. Quantification of the NPN compounds revealed their attenuation by unit operations during a trial lactose production. Urea, ammonia, glycerophosphocholine, creatine, creatinine, orotic acid and choline were the most dominant compounds. Mother liquor concentrate had the highest concentration of NPN, whereas lactose powder had substantial relative amounts of N-acetylglucosamine, phosphocholine and orotic acid. The NPN compounds added up to 57-99% of the total nitrogen, depending on the sample type. The highest nitrogen recovery was found for the reverse osmosis retentate, mother liquid concentrate, wash water and reverse osmosis permeate, whereas the lowest was found for lactose powder.