Short communication: The effect of liquid storage on the flavor of whey protein concentrate

Abstract

Unit operations in dried dairy ingredient manufacture significantly influence sensory properties and, consequently, their use and consumer acceptance in a variety of ingredient applications. In whey protein concentrate (WPC) manufacture, liquid can be stored as whey or WPC before spray drying. The objective of this study was to determine the effect of storage, composition, and bleaching on the flavor of spray-dried WPC80. Liquid whey was manufactured and subjected to the following treatments: bleached or unbleached and liquid whey or liquid WPC storage. The experiment was replicated 3 times and included a no-storage control. All liquid storage was performed at 4°C for 24h. Flavor of the final spray-dried WPC80 was evaluated by a trained panel and volatile compound analyses. Storage of liquids increased cardboard flavor, decreased sweet aromatic flavor, and resulted in increased volatile lipid oxidation products. Bleaching altered the effect of liquid storage. Storage of unbleached liquid whey decreased sweet aromatic flavor and increased cardboard flavor and volatile lipid oxidation products compared with liquid WPC80 and no storage. In contrast, storage of bleached liquid WPC decreased sweet aromatic flavor and increased cardboard flavor and associated volatile lipid oxidation products compared with bleached liquid whey or no storage. These results confirm that liquid storage increases off-flavors in spray-dried protein but to a variable degree, depending on whether bleaching has been applied. If liquid storage is necessary, bleached WPC80 should be stored as liquid whey and unbleached WPC80 should be stored as liquid WPC to mitigate off-flavors.

The Chemistry of Protein Oxidation in Food

“…The latter compound is readily formed in milk upon exposure to light, especially in clear glass bottles and is part of the “cooked” off‐flavor of milk . A cabbage‐like off‐flavor from dimethyl disulfide and dimethyl trisulfide may also occur in liquid whey protein concentrates after bleaching with H 2 O 2 …”

“…[241] A cabbage-like off-flavor from dimethyl disulfide and dimethyl trisulfide may also occur in liquid whey protein concentrates after bleaching with H 2 O 2 . [242] A"lightstruck" flavor was described for beer after shortterm exposure to sunlight in clear or green glass bottles.T he substance responsible for this flavor is 3-methylbut-2-ene-1thiol. It results from riboflavin-mediated photooxidation of sulfur-containing amino acids and the reaction with the 3methylbut-2-enyl radical formed during isohumulone degradation.…”

Die Chemie der Proteinoxidation in Lebensmitteln

“…Dieses entsteht schnell, wenn Milch dem Sonnenlicht ausgesetzt wird, vor allem in weißen Glasflaschen, und ist auch Teil des “abgekochten” Fehlaromas der Milch . Ein kohlartiges Fehlaroma infolge von Dimethyldi‐ und Dimethyltrisulfid kann auch in flüssigen Molkenproteinkonzentraten nach Bleichung mit H 2 O 2 auftreten …”

“…[241] Ein kohlartiges Fehlaroma infolge von Dimethyldi-und Dimethyltrisulfid kann auch in flüssigen Molkenproteinkonzentraten nach Bleichung mit H 2 O 2 auftreten. [242] Ein Lichtgeschmack wurde auch bei Bier beschrieben, wenn es kurzzeitig in weißen oder grünen Glasflaschen dem Sonnenlicht ausgesetzt wird. Die hierfürv erantwortliche Substanz ist 3-Methylbut-2-en-1-thiol.…”

Invited review: The effects of processing parameters on the flavor of whey protein ingredients

“…To minimize flavor effects, liquid protein retentates should be held for less than 12 h before spray drying (Whitson et al, 2011). If storage is necessary, bleached whey stored better as liquid whey, and un-bleached whey stored better as liquid WPC 80 (Park et al, 2016).…”