Off-flavors, formation

Laine, G., Gobel, C., du Jardin, P, Feussner, I., Fauconnier, M. -L. (2006). Study of precursors responsible for off-flavor formation during storage of potato flakes. J. Agric. Food Chem., 54, 5445-5452. 

Styrene can cause off-flavors in food products packed in polystyrene packaging materials. Each food product has a different sensitivity to styrene off-flavors and thus each food package system needs to be evaluated individually. The formation of styrene off-flavor in a given package/product system can be estimated a priori given the styrene threshold concentration in the food, the initial residual styrene monomer concentration in the packaging material and the desired shelf life. If this information is not readily available then accelerated storage tests followed by a sensory comparison can be carried out to evaluate the potential of off-flavor formation in the product. 

Camelina oil was also included in formulation of salad dressings. Produced dressings showed a similar stability to conventional products during several months of storage at ambient temperature without off-flavor formation (76). 

In theory, a crude cysteine-sugar reaction product with a high content of Amadori compoimd can also be used as a flavor precursor system. However, to avoid off-flavor formation, the cysteine-xylose reaction has already to be discontinued before 75% of the maximum Amadori compound concentration has been achieved. Moreover, dilution with other precursors and/or a flavor carrier is necessary for acceptable stability. In some cases, the use of mixtures of cysteine with Amadori compounds of other amino acids (5) can also be a suitable alternative for the in situ generation of meat flavors. 

The intent of this chapter is to summarize naturally occurring flavor compounds in aromatic foods, and the formation of flavor during processing of foods including the Maillard, lipid oxidation, microbial, and enzymatic reactions. A brief discussion on the impact of interactions between these components on food flavor and off-flavor formation is also included. At the end of chapter, the manufacturing of flavor compounds by the utilization of biotechnology and pyrolysis techniques is further explained. 

Proteolytic activities in foods may also result in off-flavor formation. The release of trichloroacetic acid-soluble free amino acids by proteolytic enzymes has been associated with off-flavor development [92]. On the other hand, some chemicals inherent in food products may be converted into off-flavor compounds during processing. For example, ferulic acid is a precursor of off-flavors in stored orange juice [93]. 

Effect of L-Cysteine and A -Acetyl-L-cysteine on Off-Flavor Formation in Stored Citrus... 

Limited information is available on the nature and mechanisms of off-flavors formation during citrus juice processing and storage (IJ). Some of the objectional... 

Naim M, Zuker 1, Zehavi U, RousefFRL (1993) Inhibition by thiol compounds of off flavor formation in stored orange juice. 2. Effect of L-cysteine and N-acetyl-Lcysteine on p-vinyl-guaiacol formation. JAgric Food Chem 41 1359-1361... 

Flavor changes (e.g., loss of intensity, loss of freshness, ehange of profile, off-flavor formation) occur frequently during fermentation and storage of yogurts with fruit. Radical changes in the flavor profile of strawberry flavor have been reported [3] however, the cause of the sensorial phenomenon was not studied in detail. The basic process of yogurt production is outlined in Fig. 1. The milk, milk powder, and a starter culture were mixed the mass... 

In addition, the chemical formation of aroma compounds for the synthesis of desired flavors and prevention of off-flavors is considered. Chapters 15, 21, 26, 33, and 34 discuss how light and heat can affect the formation of both desirable and undesirable flavors. Microorganisms and aging are key in off-flavor formation in dairy products, wine, and grain degradation. Potent flavor compounds are released during the processing of coffee. 

GC-O is the method of choice for selecting those components that are responsible for aroma deviation in food, i.e., an off-flavor. In general, it can be applied to both foodbome off-flavor formation and off-flavor problems related to contamination. The latter is caused by odorants that normally do not belong to the overall aroma of the product, i.e., external contaminants (e.g., packaging) or compounds formed upon processing and storage (e.g., microbial spoilage). In both cases, the comparison of the off-flavor of the contaminated food with the reference product usually results in a limited number of sensory-relevant compounds, which reflect the difference in aroma profiles. Identification work can then be focused on these odorants. 

Furthermore, volatiles produced as bacterial metabolites or from active microbial enzymes are not the only causes of off-flavors in milk and shortened shelf life. For example, chemical contaminants can generate significant off-flavor formation. Contamination of milk with relatively low levels of copper, for example, can result in formation of oxidation off-flavors during shelf life. Another nonmicrobiological cause of off-flavors that sometimes occurs in milk samples that first come off the processing line is contamination by sanitizer from pro-... 

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