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 attenu-ation 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.

Automated summary

NPN compounds from dairy processing side-streams show promise as a source for new products. The NPN profile of lactose production samples was analyzed using GC-MS and 1H NMR spectroscopy, identifying 35 NPN compounds including amino acids, organic acids, and other classes. The quantification of NPN compounds revealed their decrease during lactose production, with urea, ammonia, glycerophosphocholine, creatine, creatinine, orotic acid, and choline being the most dominant. Mother liquor concentrate had the highest NPN concentration, while lactose powder had substantial amounts of N-acetylglucosamine, phosphocholine, and orotic acid. The NPN compounds accounted for 57-99% of total nitrogen, with the highest recovery found in reverse osmosis retentate, mother liquor concentrate, wash water, and reverse osmosis permeate." The lowest recovery was found in lactose powder.