Flavour defects in edible casein and skim-milk powder: I. The role of Maillard browning

Abstract

TWO chemical tests were used to measure the extent of lactose degradation by Maillard browning in casein and skim-milk powder during storage. At the same time these products were evaluated organoleptically. Highly significant correlations between age, flavour score and level of browning in skim-milk powder were in contrast to the lack of any relationship between the flavour score or age of casein and its level of browning. Maillard browning occurring during storage of skim-milk powder was accompanied by increasing levels of cereal and malty flavours. A stale flavour, which closely resembled the musty flavour common to casein, was not observed in skim-milk powder until after storage for 9 months. A distinct difference in the flavour stability of rennet casein and acid casein could not be accounted for in terms of the relative extent of lactose degradation. Evaluation of casein samples with different lactose contents suggested that Maillard browning does not contribute to flavour defects during storage unless the curd is so insufficiently washed during manufacture as to produce an abnormally high level of lactose in the dried product.For many years commercial casein has been used primarily in the preparation of paper coatings, adhesives and plastics, with the result that properties such as viscosity, adhesive strength, solubility and ability to bind water and pigments have received considerable attention. Recently, however, the more widespread use of casein as a high-quality protein in compounded foods has required a more searching evaluation of its flavour stability.A common defect in casein may be described as a musty or stale flavour, which is sometimes detectable immediately following the drying of fresh casein curd and which becomes more pronounced during storage. Organoleptic evaluation of many casein samples has demonstrated that the musty flavour is intensified by heattreatment and that acid-precipitated caseins are considerably more susceptible to musty flavour development than are caseins precipitated by rennet.In 2 recent publications, Australian workers have investigated the nature and origin of the so-called 'gluey' flavour in casein and co-precipitates. In the first study, Ramshaw & Dunstone (1969 a) demonstrated positive correlations between gluey flavour, lactose content and the extent of Maillard browning as measured by the ferricyanide reducing value. Furthermore, the gluey flavour was not detectable by 15-2

Kinetics of Nonenzymatic Browning in Cheddar Cheese Powder During Storage

“…Specific off-flavor notes perceived were burnt, cardboard, oxidized, stale, burnt feather, burnt rubber, brothy, scorched, acid, bouillon, hydrolyzed protein, musty, and gluey that are about the same for all a,-temperature conditions. These off-flavor notes were similar to those obtained with various dried milk products (Bassette and Keeney 1960; Ramshaw and Dunstone 1969;Walker 1972; Walker and Manning 1976). Cheese-like flavor intensity also decreased with prolonged storage at both temperatures.…”

Creating Proteins with Novel Functionality via the Maillard Reaction: A Review

“…It decreases nutritional value due to blocking of lysine and other essential amino acids (Malec et al, 2002;Pizzoferrato et al, 1998). It may cause off-flavor development (Morr and Ha, 1991;Walker, 1972), poor protein solubility (Kato et al, 1986;Hannan, 1949 and1950), and decreased digestibility (Culver and Swaisgood, 1989), produce adverse browning (Guerra-Hernandez et al, 2002;Saio et al, 1980), and shorten product shelf-life (Albalá-Hurtado et al, 1999;Guyomarc'h et al, 2000;Stapelfeldt et al, 1997;Van Mill and Jans, 1991).…”

Changes in the volatile profile of skim milk powder prepared under different processing conditions and the effect on the volatile flavor profile of model white chocolate

“…Of the 22 volatile compounds identified, 11 were products of lipid oxidation, primarily straight-chain aldehydes (pentanal, hexanal, heptanal, octanal, nonanal, and decanal) and methyl ketones (2-heptanone, 2-nonanone, 2-decanone, and 2-undecanone). These compounds have all been identified previously in heated milk (Vazquez-Landaverde et al, 2005) and SMP (Bassette and Keeney, 1960;Walker, 1972;Shimamura and Ukeda, 2012), although they are generally considered to contribute off-notes to SMP flavor. Autoxidation of lipids in milk is catalyzed by both light and heat and therefore any processing stage that applies heat and exposes the milk to light would be expected to increase the concentration of lipid oxidation products.…”