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Chemical and physical changes during the storage of dehydrated vegetables
|Autor:||Gamboa-Santos, Juliana ; Soria, Ana C. ; Corzo-Martínez, Marta ; Villamiel, Mar ; Montilla, Antonia|
|Fecha de publicación:||2012|
|Resumen:||Drying is one of the oldest methods of food preservation and represents a very important process in the food industry, forced convection by hot air being the most common industrial technique to perform (Gowen et al., 2008). Convective drying can be carried out at high temperatures for short times or at lower temperatures for longer times; the former option being usually preferred since it produces less thermal damage and consume less energy (Velic et al., 2004). Among the different foods that can become dehydrated, vegetables hold a predominant position as they can be consumed either on their own or as ingredients for the elaboration of other food products such as soups, sauces, etc. Dehydration by hot air may cause a series of physical, physicochemical, chemical and biological alterations that can affect the final quality of the dehydrated vegetable. One of such chemical modifications which can take place if dehydrated vegetables are subjected to intensive treatment and/or inappropriate storage is the Maillard reaction (MR). MR takes place between the carbonyl group from reducing sugars and the free amino group of amino acids, peptides or proteins. Advanced stages of MR should be avoided because a loss in the nutritional value of the food may occur and the development of undesirable coloured and fluorescent compounds, together with the formation of new volatile compounds, can alter the organoleptic properties of the product (Villamiel et al., 2006). In addition, dehydration produces shrinkage and may affect negatively the rehydration ability of the final product (Panyawong & Devahastin, 2007). This is due to a series of factors related to physical and physicochemical changes occurring in the tissues (Krokida & Maroulis, 1997), and also to chemical changes that might affect carbohydrates and proteins (Soria et al., 2010). Similarly to MR, these changes can be also influenced not only by processing but also by the storage conditions. This work has been devoted to investigate several quality parameters including major and minor carbohydrates, 2-furoylmethyl-aminoacids (as indicators of MR), proteins, polyphenols and rehydration ability (expressed as rehydration ratio, RR) in highly consumed industrially dehydrated vegetables.|
The effect over them of a controlled storage under similar conditions used in the market and by the consumers has also been studied. Six industrially dehydrated samples were analysed: two geometries of carrot (Daucus carota) cubes and flakes (carrots I and II, respectively) and onion (Allium cepa) two sizes of flakes (small, onion I; large, onion II), one sliced garlic (Allium sativum) and one flake potato (Solanum tuberosum) kindly provided by a Spanish vegetable products company (Vegenat, Badajoz, Spain). Dehydrated samples, packed in polypropylene individual bags (30 mm thick sample layer) and closed, were stored in the dark for a period of 12 months under the following ambient conditions: temperature between 19.3 and 27.1 ºC; relative humidity between 15.0 and 40.7%. After 6 and 12 months of storage, samples were taken for the corresponding analysis. The obtained results showed that storage conditions assayed in the present paper have no appreciable effect on the quality parameters studied (dry matter, rehydration ability, total polyphenols, MR indicators, proteins and carbohydrates), probably due to the fact that the vegetables were properly treated and dehydrated at the industry. Therefore, from this point of view, it has been probed that these dehydrated carrot, potato, onion, and garlic are sufficiently stable for at least 12 months. These results are of particular relevance in the case of constituents with certain bioactivity. Moreover, the scarce MR advance also guarantees the preservation of nutritive value due to lysine, the most important substrate of RM during the storage. As nowadays there is an increasing interest in the use of dehydrated vegetables as food ingredients in the elaboration.
|Descripción:||Resumen del póster presentado al International Congress of Chemical Engineering celebrado en Sevilla (España) del 24 al 27 de junio de 2012.|
|Aparece en las colecciones:||(IQOG) Comunicaciones congresos|
(CIAL) Comunicaciones congresos
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