Vitamin C content and sensorial properties of dehydrated carrots blanched conventionally or by ultrasound (original) (raw)
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Chemical and Physicochemical Quality Parameters in Carrots Dehydrated by Power Ultrasound
Journal of Agricultural and Food Chemistry, 2010
The preservation of the quality and bioactivity of carrots dehydrated by power ultrasound (US) under different experimental conditions including prior blanching have been evaluated for the first time by measuring the evolution of the Maillard reaction and the changes in soluble sugars, proteins, total polyphenols, antioxidant activity and rehydration ability. This study also includes a comparison with a freeze-dried sample and data of commercial dehydrated carrots. The synergic effect of US and temperature (60 ºC) increased the dehydration rate of carrots (90 % moisture loss in only 75 minutes), while still providing carrots with a level of 2-furoylmethyl-amino acids significantly lower than that of dehydrated commercial samples. Whereas a decrease in the content of reducing soluble sugars was observed with processing temperature, minor carbohydrates (scyllo-and myo-inositol and sedoheptulose) were rather stable irrespective of the US dehydration parameters. Blanching significantly improved the rehydration ability of US-dehydrated carrots, without increasing the loss of soluble sugars by leaching. As supported by the similarity of most quality indicators studied in both US-treated and freeze-dried carrots, the mild processing conditions employed in US dehydration gave rise to premium quality dehydrated carrots.
Estimation of Vitamin C in Carrot Before Cooking and After Cooking
SciencePG, 2016
The change of vitamin C content of fresh and cooked carrot (Daucus carota) is a subject of considerable concern and investigation. In the last few years, some research is showing the changes of the vitamin C content of fresh and cooked foods. This study has been aimed to present the estimation vitamin C content of fresh and cooked carrot. Vitamin loss can be induced by a number of factors. Obviously, losses of vitamins depend on cooking time, temperature, and cooking method. Some vitamins are quite heat-stable, whereas others are heat-labile. Many other factors than heat can destroy (some) vitamins, such as: solubility in water, exposure to air (oxidation), exposure to light (UVs), heat, acid and alkaline solutions, storage losses, etc. An essential nutrient found mainly in vegetables. The body requires vitamin C to form and maintain bones, blood vessels, and skin. Vitamin C is also known as ascorbic acid. Vitamin C is a water-soluble vitamin. It must be replenished daily. Vitamin C helps make collagen, a protein needed to develop and maintain healthy teeth, bones, gums, cartilage, vertebrae discs, joint linings, skin and blood vessels etc. From our study, we observed that vitamin C contains 5.8% in uncooked carrot and after cooking the content of vitamin C is 2.6%. From the study, we can say that the content of vitamin C decreases with respect to cooking. So if we heat foods for long time then the content of vitamin C becomes low.
Food Chemistry, 2013
The effect of previous ultrasound and conventional treatments on drying and quality parameters (furosine-as indicator of lysine participation in the Maillard reaction-, carbohydrates, total polyphenols, protein profile, rehydration ratio, microstructure changes) of convective dehydrated carrots has been assessed. The most striking feature was the influence of blanching on the subsequent furosine formation during drying, probably due to changes in the protein structure. The highest values of furosine were found in carrots conventionally blanched with water at 95 ºC for 5 min. However, samples previously treated by ultrasound presented intermediate values of furosine and carbohydrates as compared to the conventionally blanched samples. Dried carrots previously subjected to ultrasound blanching preserved their TPC and showed rehydration properties, which were even better than those of the freeze-dried control sample. The results obtained here underline the usefulness of furosine as an indicator of the damage suffered by carrots during their blanching and subsequent drying.
This study was conducted to investigate effects of varying levels of pretreatments on nutrient retention and sensory acceptance of solar-dried carrot slices. The carrot samples were blanched at 55, 65 and 75℃ for 45 minutes, soaked in 5%, 10% and 15% salt solutions for 5 hours and dried using an indirectly heated passive type solar dryer. The best nutrient retentions (5.25% protein db, 2.49% fat db, 2.17% fiber db and 71.94 ppm β-carotene) were recorded for samples treated at 55℃ whereas the 5% salt solution resulted in 2.88% fat, 2.46% fiber and 73.89 ppm β-carotene. The highest crude protein (5.68% db) and crude fiber (2.99% db) were recorded for the combination of 55℃ with 15%, and the highest crude fat (3.20% db) and β-carotene (74.97 ppm) were obtained from the samples subjected to 55℃ and 5%. High total ash contents were associated to high levels of osmotic concentrations irrespective of the blanching temperatures. Concerning the sensory acceptance, color, flavor, taste, texture and overall acceptance of samples blanched at 55℃ and soaked in 10% solution were most liked. In most cases, the physicochemical, nutritional and sensory acceptance of the samples treated with 55℃ blanching temperature and 5% salt concentration and combination of the two was observed to be superior to other treatment levels. Keywords: Carrot, Blanching, Osmotic dehydration, Solar drying, Nutrient retention, Beta-carotene, Sensory acceptance
NUTRITIONAL, SENSORY AND REHYDRATION CHARACTERISTICS OF SOLAR-DRIED CARROTS AS AFFECTED
This study was conducted to investigate effects of varying levels of pretreatments (blanching temperature and osmotic concentration) on rehydration characteristics, nutrient retention and sensory acceptance of solar-dried carrot slices. Blanching is used to combat the problems of discoloration by enzymes. Osmotic pretreatment enhances drying rate, reduces nutrient degradation during drying and storage and results in good quality dehydrated carrot. The carrot samples were blanched at 55, 65 and 75°C for 45 minutes, soaked in 5%, 10% and 15% salt solutions for 5 hours and dried using an indirectly heated passive type solar dryer. Rehydration capacity of the dried carrots was determined by soaking 20 g sample in hot water at 95°C for 10 minutes and rehydration kinetics was carried out by soaking 5 g samples at 75, 85 and 95°C. Blanching temperature, osmotic concentration, and their interaction significantly affected the physicochemical properties of the carrot slices. High values of rehydration capacity (157.19) and low lixiviated soluble solids (5.47°B) were determined for samples treated at blanching temperature of 55°C. Similarly the smallest salt concentration (5%) resulted in the highest value (188.65) of rehydration capacity and lowest value (4.25°B) of lixiviated soluble solids. The interaction of 65°C blanching temperature with 5% osmotic concentration produced the highest rehydration capacity (214.65) and that of 55°C with 5% gave the lowest (4.20°B) soluble solid loss. The highest soluble solid loss corresponded to samples treated with 15% salt solution combined with all levels of blanching temperature. Best nutrient retentions (5.25% protein db, 2.49% fat db, 2.17% fiber db and 71.94 ppm β-carotene) were recorded for samples treated at 55°C whereas the 5% salt solution resulted in 2.88% fat, 2.46% fiber and 73.89 ppm β-carotene. The highest crude protein (5.68% db) and crude fiber (2.99% db) were recorded for the combination of 55°C with 15%, and the highest crude fat (3.20% db) and β-carotene (74.97 ppm) were obtained from the samples subjected to 55°C and 5%. High total ash contents were associated to high levels of osmotic concentrations irrespective of the blanching temperatures. Concerning the sensory acceptance, color, flavor, taste, texture and overall acceptance of samples blanched at 55°C and soaked in 10% solution were most liked. A first-order kinetic model was used to describe the rehydration kinetics in terms of rehydration rate constant (k) and equilibrium moisture content (Me). A better rehydration performance was observed corresponding to the samples treated at 55°C blanching temperature and soaked in 5% salt solution. In most cases, the physicochemical, nutritional and sensory acceptance of the samples treated with 55°C blanching temperature and 5% salt concentration and combination of the two was observed to be superior to other treatment levels.
Acta Horticulturae et Regiotectuare, 2013
The average vitamin C content of fresh carrots was 56 mg.kg-1. Amount of vitamin C was reduced by the length of storage and storage environment. On average, the most significant decrease in vitamin C to 24.4 mg.kg-1 under laboratory conditions was reported after 56 days when stored carrots were packed in plastic box. When stored in a refrigerator, the vitamin C content decreased to 24.7 mg.kg-1 after 126 days of storage in a plastic box. During both experimental periods in laboratory conditions, the most vitamin C was preserved while being wrapped plastic wrap. This way of packaging also enabled relatively long-term preservation of freshness in variety called “Komarno”, which was up to 60 days. The second best option in this respect is the packed carrot in microtene bags. The least convenient was to store the carrots open without packaging. In the case of refrigerated storage, the options of packaging in plastic wrap and microtene bags were also the best. The most significant declin...
Journal of Food Processing and Preservation, 1994
Low temperature long time (L E T) blanching (70C for 20 min) together with calcium treatment can be used to significantly improve the texture of rehydrated dried carrots when compared to high temperature short time (HTST) blanching (I OOC for 3 min). LTL.T blanching allows pectin methyl esterase to deesterifi pectin, which can then react with calcium to form salt bridges. 0.3% L-cysteine-HCl was found to be most effective in preventing ascorbic acid loss and obtaining a product with the highest rehydration ability, compared to pretreatments with 0.3 % N-acetyl-L-cysteine and 0. I % sodium metabisulphite. On the other hand 0. I % sodium metabisulphite was most effective in preserving the carotenoids content of dried carrots. Ascorbic acid and rehydration ability were more adversely affected by long drying time than high drying temperature, while carotenoids were more sensitive to high drying temperature than drying time. Hence, 60C drying temperature was good for ascorbic acid and rehydration ability, while 40C drying temperature was good for carotenoid and color of dried carrots. 1987), including canned carrots (Lee er af. 1979). This was because at this 'To whom correspondence should be addressed.
Effects of different cooking methods on the vitamin C content of selected vegetables
Nutrition & Food Science, 2013
PurposeVegetables are rich in vitamin C, but most of them are commonly cooked before being consumed. The objective of the present study was to evaluate the effects of three common cooking methods (i.e. steaming, microwaving, and boiling) on the vitamin C content of broccoli, spinach, and lettuce.Design/methodology/approach100 g of homogeneous pieces of broccoli, spinach, and lettuce was separately processed for 5 minutes by steaming, microwaving, and boiling. A simple UV analytical method was employed to determine the vitamin C content of the vegetables.FindingsLoss of vitamin C in broccoli, spinach, and lettuce during steaming was 14.3, 11.1, and 8.6 per cent, respectively, while the loss of vitamin C during boiling was 54.6, 50.5, and 40.4 per cent, respectively. During microwaving, loss of vitamin C in broccoli, spinach, and lettuce was 28.1, 25.5, and 21.2 per cent, respectively.Practical implicationsThis study shows that any raw vegetable contains the highest content of vitamin...