Undesirable Sulphur and Carbonyl Flavor Compounds in UHT Milk: A Review

Abstract

Ultra High Temperature (UHT) processing leads to the formation of "cooked" and "flat" flavors in milk. These undesirable notes occur due to the volatile formation of a variety of sulphur containing compounds, methyl ketones and aliphatic aldehydes, derived from the constituents of the milk's matrix during thermal processing and storage. The "cooked" flavor of UHT milk is associated with the presence of a variety of sulphur containing compounds while the "stale" flavor is characterized by the dissipation of these sulphur volatiles and an increase of the formation and presence of both methyl ketones and aliphatic aldehydes over time. The extent to which the individual volatiles contribute to the overall flavor of UHT milk is not clear. The proposed formation of these volatiles, that is, the methods to control the intensity of "cooked" and "stale" flavors associated with UHT milk and extraction techniques for the isolation of these volatiles from milk, have been reviewed.

Microbiological and Sensory Quality of Milk on the Domestic Market

“…For consumers, fl avour is one of the most signifi cant quality attributes owing to the overall acceptability of a food product. some consumers fi nd the fl avour of UHT milk to be undesirable [Zabbia et al, 2012;Clare et al, 2005].…”

Effect of ultra‐high‐pressure homogenization at moderate inlet temperatures on volatile profile of milk

“…These compounds have an important effect in milk flavor, especially the aliphatic aldehydes (Zabbia et al, ). The aldehydes found in UHPH and UHT were linear aldehydes such as pentanal, hexanal, heptanal, octanal, and the aromatic benzaldehyde (Table ).…”

“…Most of these compounds are commonly formed by auto‐oxidation of unsaturated fatty acids and the spontaneous decomposition of hydroperoxides being promoted by heat and light that may increase their amount during storage. Others aldehydes are produced by degradation of various aminoacids by the Maillard reaction (Contarini et al, ; Vazquez‐Landaverde et al, ; Zabbia et al, ).…”

“…After that, the dimethyl disulfide may be transformed into dimethyl thrisulfide (DMS). Although, hydrogen sulfide was considered the major contributor to the cooked flavor of heat‐treated milk, other studies concluded that the DMS and methanothiol are compounds with higher impact in the cooked flavor of heat‐treated milk (Vazquez‐Landaverde et al, ; Zabbia et al, ). Although DMS was the only sulfur compound detected in the UHPH and heat‐treated milk samples, significant differences ( p < .05) were observed among them.…”

“…Besides, similar results were observed for other long-chain ketones compounds, such as 2-octanone, 2-nonanone, and 2-undecanone. In heat-treated milk (particularly bottle sterile milk), the cooked aroma is related to the presence of long-chain ketones (Contarini et al, 1997;Vazquez-Landaverde, Torres, & Qian, 2006a;Zabbia, Buys, & de Kock, 2012). Contarini and Povolo (2002) evaluated the volatile profile of pasteurized, UHT and in-bottle-sterilized milk, finding that the 2-heptanone was the most distinguishing compound, suggesting the possibility of employ it as a volatile heat marker of milk.…”