Effect of Different Blanching Treatments on Physicochemical, Phytochemical Constituents of Cabinet Dried Broccoli

Broccoli (Brassica oleracea italica) is a winter vegetable of Italian origin. It is one of the most important member of the Cole group of vegetables and widely considered to contain high level of phytochemicals including glucosinolates and flavonoids. Being rich in phytochemicals, it has been described as a vegetable with high nutritional values [1]. These phytochemicals and nutrients have gained renewed interest in preventing cancer, cardiovascular diseases and stimulate the immune system [2]. Broccoli florets have a shorter shelf-life as a result of high rates of respiration and metabolism, during which many chemical reactions occur [3]. Therefore, new approaches were developed to extend the shelf-life of intact or fresh-cut broccoli in order to control the senescence and quality decay by various means, like modified atmosphere packaging [4], UV-C treatments [5], heat treatments like hot water [6]. These treatments have been observed to effectively reduce yellowing of stored fresh broccoli. Some other scientists used dehydration technique for preservation of broccoli [7]. Food dehydration refers to the complete removal of water from foods under controlled conditions. During dehydration some important changes take place, as structural and physicochemical modifications that affect the final product quality and also result in lower shipping and container cost. Dehydrated foods have increased shelf life, inexpensive than the fresh ones or canned ones, and also leads to the production of convenience items. These processed products are excellent as emergency foods and widely used in army, military and hiking etc. Thus, dehydration techniques were used to maintain quality criteria like color, nutritional composition, shape or texture. Typically, blanching is carried out by treating the vegetables with steam or hot water for 1-10 min at 75-95 ◦ C, the time/ temperature combination depending on the type of vegetable [8]. Blanching of foods involves mild heating in water and serves. Blanching can have negative effect on nutrients such, as vitamins and phenolic compounds which are relatively unstable when subjected to heat treatments [9]. Apart from processing, storage conditions and domestic cooking and preparation have significant effect on phytochemicals such as ascorbic acid and phenols [10]. Salt blanching can also be carried out to preserve the essential nutrients. Therefore, there is need to standardize the technique for drying of broccoli and to study the effect of different blanching treatments on physicochemical, phytochemical constituents and antioxidant activity of dried broccoli. Abstract The present investigation was carried out to study the effect of different blanching treatments on physicochemical, phytochemical constituents of cabinet dried broccoli. Blanching treatments such as potassium metabisulphite 0.1 per cent, sodium bicarbonate 0.1 per cent, sodium chloride 1 per cent, calcium chloride 0.5per cent in water at 100oC for 180 seconds and steam blanching for 300 seconds were found suitable for cabinet drying at 50oC for 8 h on the basis of color. Results showed that the moisture, rehydration ratio, acidity and ascorbic acid were highest in potassium metabisulphite blanched sample while total phenols and antioxidant activity were highest in control (untreated sample) and total chlorophyll and color attributes were found maximum in sodium bicarbonate blanched sample, immediately after dehydration. During storage of six months significant (p≤0.05) decrease was observed in acidity, ascorbic acid, total phenols, antioxidant activity, rehydration ratio, total chlorophyll and color values in all the samples of dried broccoli but there was significant (p≤0.05) increase in moisture content. Six months storage showed best retention of moisture, rehydration ratio, acidity, ascorbic acid, total phenols and antioxidant activity in potassium metabisulphite blanched samples, while retention of total chlorophyll and color attributes were maximum in sodium bicarbonate blanched samples.