Flavour deterioration

SHAHIDI F and PEGG R (1994) Hexanal as an indicator of meat flavour deterioration, /Food Lipids, 1, 177-86. 

Cloves are best used whole. The flavour deteriorates quickly once it is powdered. Whole and ground cloves are used to enhance the flavour of meat and rice dishes. They are used widely in curry powders and masalas. In North Indian cuisine, cloves are used in almost every sauce or side dish made, mostly mixed with other spices. In South India, they find extensive use in biriyanis to enhance the flavour of the rice. They are highly valued in medicine as a carminative and stimulant. Cloves are said to be a natural anthelmintic. 

Source LFllrich, F. and Grosch, W., Flavour deterioration of soya-bean oil identification of intense odour compounds formed during flavour reversion, Fat Science Technology, 90 932-6, 1988... 

FORMATION OF CLN IN VEGETABLE OILS AND ITS IMPACT ON FLAVOUR DETERIORATION... 

CLN has three double bonds as same as LN. However, CLN is more easily oxidized than LN to prodnce polymers as the main oxidation products (Suzuki et al., 2004). This oxidation proceeds via free radical chain reaction and the radicals formed initiate the oxidation of PUFA in vegetable oils. Thus, CLN acts as an oxidation inducer as well as flavour reversion precursor. Canola oil contains relatively lower CLN as compared with other vegetable oils (Table 16.1), indicating that canola oil is stabler than oxidative and flavour deterioration. 

Enzymatic maceration, which is a softening of plant tissue by the use of enzymes, has some potential quality advantages over mechanical-thermal disintegration as maceration is obtained with less damage to the cell walls. The major part of the plant cells remains intact by enzymatic maceration [25], as the enzymes attack only the space between the cells, and with only rare injury to the cell membrane [26]. The intact cells protect nutritional components within the cells which minimise flavour changes and deterioration on storage [27,28]. 

Odorants that cause aroma changes, e.g. olf-flavours, may be detected by a comparative AEDA of fresh and deteriorated samples. Studies on storage defects of soybean oil [22, 51], buttermilk [52], boiled cod [53], dry parsley [54] and black and white pepper [55] are examples. 

Guth, H. and Grosch, W. 1990. Deterioration of soya-bean oil Quantification of primary flavour compounds using a stable isotope dilution assay. Lebensm.-Wiss. Technol. 23 513-522. 

Non-carbonated RTD beverages have shown some considerable growth in recent years mainly because of the availability of aseptic packaging forms. Still drinks that rely on chemical preservation or hot-pack/in-pack pasteurisation suffer from a number of potential problems, including rapid flavour and colour deterioration. 

Antioxidants (e.g. BHA, ascorbic acid) Less than 100 ppm, subject to user-country legislation Prevent oxidation, limit flavour and colour deterioration... 

Yeasts are classified with the fungi and are unicellular for most of their life-cycle. Together with moulds and bacteria they can bring about a deterioration in flavour, producing taints, off-notes, differences in mouthfeel and so on. Most yeasts can grow with or without oxygen, whereas most bacteria cannot survive in it. Hie majority of yeasts thrive in temperatures between 25 and 27°C some can survive at temperatures over 70°C and others can exist, apparently quite... 

The particular issues that must be addressed when non-carbonated beverages are to be produced relate mainly to the prevention of microbial spoilage and the deterioration of product taste and appearance as a result of oxidation, and to enhancement of flavour. Carbonated beverages use the presence of carbonation to boost flavour characteristics and provide palate stimulation. 

A further potential problem with non-carbonated RTD products is that they invariably contain atmospheric air in their headspace as there is no carbon dioxide to displace it. This often leads to undesirable oxygen levels in the product with resulting flavour and colour deterioration in a short time period. 

The issue of appearance as it relates to the cosmetic perfection demanded by consumers and supermarkets alike is a fundamental point. It is obvious that even organic customers will buy on appearance. Misshapen, blemished and deteriorating fruit and vegetables represent less value for money and more preparation time. It must also be remembered that the Grading Standards for Fresh Fruit and Vegetables mandate the need for a minimum Class II attainment for most (but not all) types of fresh produce. However, many consumers of organic fruit and vegetables are equally interested in taste and flavour. 

The vocabulary varies. Off-flavour is an atypical flavour often associated with deterioration of the product. Taint is often used as a synonym for off-flavour. 

Releasing packaging actively adds components to packaged food, e.g., carbon dioxide, antioxidant or preservatives to avoid deterioration of the food. Also releasers may be used, like flavour or colour releasers, to improve the quality of the food. 

Another potential area of application of FTIR spectroscopy is in the determination of the oxidative status or stability of an oil. Autoxidation is a major deteriorative reaction affecting edible fats and oils, and it is of major concern to processors and consumers from the standpoint of oil quality, as the oxidative breakdown products cause marked off flavours in an oil. A wide range of end products are associated with the autoxidative deterioration of fats and oils, the most important being hydroperoxides, alcohols, and aldehydes. Moisture, hydrocarbons, free fatty acids and esters, ketones, lactones, furans, and other minor products may also be produced, with the free fatty acids becoming more important in thermally stressed oils. In addition, there is significant cis to trans isomerisation and conjugation of double bonds in the hydroperoxides formed as an oil oxidises. 

The stability of canola oil is limited mostly by the presence of linolenic acid, chlorophyll and its decomposition products and other minor components with high chemical reactivity, such as trace amounts of fatty acids with more than three double bonds. These highly unsaturated fatty acids can be formed during refining and bleaching (Chapman et al. 1994). The presence of 7-11% of linolenic acid in the triacylglycerols of canola oil places it in a similar category to soybean oil with respect to flavour and oxidative stability. The deterioration of flavour as the result of auto- and photo-oxidation of unsaturated fatty acids in oils and fats is referred to as oxidative rancidity. 

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