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The effect of epigallocatechin gallate enriched green tea extract (GTE) on flavor, Maillard reactions and protein modifications in lactose-hydrolyzed (LH) ultrahigh temperature (UHT) processed milk was examined during storage at 40 °C for up to 42 days. Addition of GTE inhibited the formation of Strecker aldehydes by up to 95% compared to control milk, and the effect was similar when GTE was added either before or after UHT treatment. Release of free amino acids, caused by proteolysis, during storage was also decreased in GTE-added milk either before or after UHT treatment compared to control milk. Binding of polyphenols to milk proteins was observed in both fresh and stored milk samples. The inhibition of Strecker aldehyde formation by GTE may be explained by two different mechanisms; inhibition of proteolysis during storage by GTE or binding of amino acids and proteins to the GTE polyphenols.

A comprehensive technical feasibility study was conducted of a bioethanol demonstration plant with the aim of converting parts of an existing fuel-grade bioethanol production into a more valuable solvent-grade ethanol. The study focuses on the separation unit, which consists of three consecutive distillation columns and a dehydration step using molecular sieves. This separation unit did not permit sufficient removal of crotonaldehyde and methanol for obtaining solvent-grade ethanol. Therefore, an additional distillation column after the dehydration step was investigated by simulation. It is operated at subatmospheric pressure and enables simultaneous removal of methanol, crotonaldehyde, and water in the distillate. The distillate meets the fuel-grade ethanol specifications, while the bottom product meets the solvent-grade specifications. It enables around 70% solvent-grade ethanol production and employs a vacuum pump that is already used in the considered plant. A stationary operating point is characteriz...

Wort from the barley varieties (Hordeum vulgare) Pallas, Fero, and Archer grown on the same location were investigated for their influence on oxidative stability and volatile profile during wort processing. Barley varieties had a small influence on radical formation, thiol-removing capacity, and volatile profile. Wort boiling with and without hops had a large influence on these same parameters. Potentially antioxidative thiols were oxidized in sweet wort, but reduction of thiols using tris(2-carboxyethyl)phosphine hydrochloride revealed that Archer wort had a significantly larger content of total thiols than Pallas and Fero. Oxidized thiols resulted in gel proteins and longer filtration time for Archer wort. Our study shows that wort processing to a large extent will eliminate variations in volatile profile and thiol levels in wort which otherwise might arise from different barley varieties.