This study was carried out to produce products having high nutritional value from lemon grass with valencia orange, Egyptian lime and cantaloupe juices available all the year besides studying the factors affecting on quality of products after processing and during storage. Blends were prepared from lemon grass extract with orange, lime and cantaloupe juices at a ratio of 1:1, 2:1 and 3:1(wt:wt), respectively .Results indicate that total carbohydrates, fat, ash, total phenols and ascorbic acid contents of lemon grass leaves were 75.73, 4.15, 9.47, 3.76% and 175.11 mg/100g (on dry weight basis) ,respectively. Results illustrate that total soluble solids (T.S.S.) of blends ranged from 15 -15.3%, total sugars from 79.51 to 88.86%, ash content (1.83-2.56%), total phenols content (0.410 -0.812%) and ascorbic acid content (23.02-152.4mg/100g) on dry weight basis. Results show that statistical analyses for sensory evaluation of nectars were accepted for orange juice at a ratio of 2:1 and lemon grass extract: lime juice at a ratio of 3:1.The chemical composition of products was slightly affected by storage, while statistical analyses for sensory evaluation of nectars ascertained that they were accepted till 9 months of storage at room temperature. Also, results show that total bacterial count was less than 10 cfu/gfor nectars during storage.
This study was carried out to assess the quality parameters of osmo-dried red carrots pretreated with various types of osmotic sucrose syrup i.e. 40%, 50%, 60% and 70%sucrose syrup, compared with those produced by untreatedred carrots(control).The sucrose syrup 70% had the lowest osmosis time for osmosedcarrots followed by 60%, 50%, and 40% sucrose syrup respectively. However, the reduction time of dehydration for both red carrots caused the increase in solid gain (SG) and total solids (T.S) than that obtained bythe control (untreated) drying. Furthermore, the dehydration parameters (WL and WC) were strictly related to the type and concentration of the used osmosis solution.The phsico-chemical properties, microbiological assessment and quality attributes of both osmo-dried and controlred carrotsjust after processing and during storage for 6 months were also undertaken. Results indicate that, osmo-dried red carrotspretreated with sucrose syrup 70% had the highest retention of ascorbic acid followed by 60%, 50% and 40% sucrose syrup, respectively. Reducing sugars content ranged between 51.69 to 56.50% for osmos-dried red carrotswith various pretreatments just after processing. While, the corresponding values of fibers ranged from 9.53 to 9.75% respectively. The control-dried carrots had the highest total microbial counts (9.1x102 cfu/g) followed by osmo-dried pretreated with sucrose syrup 40% (6.3x 102cfu/g), 50% sucrose syrup (5.2 x102cfu/g), 60% sucrose syrup (3.7x102cfu/g) and 70% sucrose syrup (2.6x102cfu/g), respectively. On the other hand, all tested counts of microorganisms either total counts of bacteria or yeasts and molds showed proportional reduction with extending the storage period and reached to the maximum reduction after 6 months of storage.The osmo-dried red carrotspretreated with sucrose syrup 70% recorded the highest scores of color, texture, taste, flavour and overall acceptability followed by osmo-dried samples pretreated with 60%,50% and 40% sucrose syrup and the un treated (control) just after processing and after 3 and 6 months of storage at ambient temperature. Therefore, pretreatment of carrots with osmotic sugar solution to produce osmo-dried product played an important role for producing high quality dried red carrotsthan those produced by the control drying process.
The effect of antioxidant properties as free radical scavenging activity and phytochemical compounds of fresh and dried samples of dill, parsley, coriander, peppermint and celery leaves were studied. Moreover, the chemical constituents and the content of minerals in these medicinal and aromatic plants were also investigated. Results explained that the contents of total phenolics ranged from 1446.88 for coriander to 3128.57mg/100gm for peppermint and after the drying process decreased to 1280.10 and 2356.45mg/100gm, respectively. Also, peppermint had the highest content of flavonoids, while the lowest content was observed in coriander leaves. Otherwise, fresh coriander leaves had the highest content of carotenoids, while the lowest content was in the fresh peppermint leaves. Results explained also that the main component of phenolic compounds was protocatchuic in all fresh and dried samples under investigation. Celery leaves had the highest protocatchuic content. Concerning minerals content reveal that the parsley leaves had the highest content of calcium, potassium and magnesium, while peppermint had the highest phosphorus and iron contents. Results also show that celery leaves had the highest sodium content. Fresh dill and peppermint recorded the highest percentages of total antioxidant activity. Also, fresh celery had gradual effect on DPPH compounds being used as synthetic free radical. Coriander and parsley showed the lowest antioxidant activity. After the drying process total antioxidant activity decreased. Slight decrease was observed with dill and peppermint leaves, while celery and parsley leaves were more effective by using the air oven drier process.
The present study aims to use microwave power to facilitate the extraction of pectin from dried mango peels, and also to explore the effect of power on some quality parameters of the resultant pectin. Chemical composition of dried mango peels ascertained a high percent of total pectin, being 16.01 % (on dry weight basis). With respect to microwave heating, the optimal experimented power was 600W, and 6 minutes as the best short holding time, which gave 12.80 % yield, 86.54% recovery and 77.20% anhydrogalacturonic acid (AGA) of extracted pectin. Comparing to the commercial pectin, the results of some physicochemical characterstics of isolated pectin, revealed that the pectin isolated by microwave heating from mango peels, being to some extent analogous to the commercial pectin with respect to its qualities, such as high methoxyl pectin, high degree of estrification (DE), and high percent of AGA besides its high viscosity, followed by the pectin isolated using the conventional method. Statistical analysis of organoleptic data showed no significant differences between strawberry jam prepared by using commercial pectin and that treated with pectin isolated by microwave heating as affecting their texture, color, taste and preference. Besides, high significant differences were detected between various concentrations of added pectin, with respect to the texture alone. Generally, the utilization of pectin isolated from mango peels using microwave heating in jam processing gave high quality attributes resembling that of the commercial pectin when added to strawberry jam and this would also lead to gain economical benefits.
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