Briefly, the firedrake fruit Peels will be dried utilizing three methods, which are oven dry, vacuum dry, and micro-cook prohibitionist. The colour, phenolic content, betacyanin content, antioxidant activity of the firedrake fruit pulverization for each drying method and fresh Peels will be compared. The H2O activity of the pulverization will be determined. All the measuring will be performed in triplicate.
Absolute ethyl alcohol, Folin-Ciocalteu reagent, Na carbonate, Gallic acid, distilled H2O, Trolox ( 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid ) 97 % , TPTZ ( 2,4,6-tripyridyl-s-triazine ) & gt ; 98 % , ferrous chloride hexahydrate ( FeCl3. 6H2O ) Na ethanoate trihydrate, methyl alcohol, hydrochloric acid ( HCl ) .
Convection oven, Vacuum oven, Microwave oven, bomber, homogenizer, Buchner funnel, rotary evaporator, H2O bath, UV-spectrophotometer, Labscan, XE, Hunter Lab. Inc. , USA, AquaLab Series 3 Water Activity Meter.
Dragon fruit ( Hylocereus polyrhizus ) will be obtained from different stables in Pasar Tani FAMA, Serdang.
5 kilogram of firedrake fruit will be obtained. Then the fruits will be washed and peeled. The Peels will be washed exhaustively to take soil and unwanted/spoilage portion.
The firedrake fruit Peels will be oven-dried in a convection oven, vacuum-dried and micro-cook dried. 500g Peels will be used for each drying method.
For oven drying, the Peels will be dried in an oven at 55 oC until the Peels reached a changeless weight. This temperature is chosen because harmonizing to Larrauri ( 1999 ) , drying temperature below 65oC able to avoid alterations in the functional belongingss and in the content of polyphenols, tannic acids, anthocyanidins and proteins.
For vacuity drying, the procedure will be carried out harmonizing to Krokida, Maroulis, and Saravacos ( 2001 ) with little alteration. Vacuum drying is will be carried out utilizing vacuity drier at 65oC A± 0.2oC. and 33 mbar A± 3 % , until changeless weight.
In microwave drying, the Peels will placed in the center of the turntable of a commercial microwave oven at 540W ( Inchuen, Narkrugsa, & A ; Pornchaloempong, 2010 ) .
Time taken for drying will be measured and recorded.
All the dried samples will be grinded utilizing a bomber factory and sieved to obtain a pulverization atom size.
Furthermore, freeze-drying is known to hold high extraction efficiency because ice crystals formed within the works matrix can tear cell construction, which allows issue of cellular constituents and entree of dissolver, and accordingly better extraction ( Asami, Hong, Barrett, & A ; Mitchell, 2003 ) . ( Effects of different drying methods on the antioxidant belongingss of foliages and tea of ginger coinage ) .
3.4 Extraction of Samples
Dried Peels for each drying method will be extracted by a method reported by Dewanto, Wu, Adom, & A ; Liu ( 2002 ) with little alteration. Briefly, the dry equivalent of 100 g of Peel pulverization or fresh Peel will be blended with 200ml 80 % ethanol solution and homogenise for 5 min utilizing a Virtis 45 homogenizer. The slurry will be filtered through Whatman No. 1 filter paper in a Buchner funnel under vacuity. The filter bar is washed twice with 15 milliliters of ethanol solution. The filtrate is evaporated utilizing a rotary evaporator at 45 A°C until less than 10 % of the initial volume remained. The infusion is frozen at -40 A°C until analysis.
3.5 Entire Phenolics Content
Entire phenolic content will be analyzed, utilizing the Folin-Ciocalteu method described by Sato et Al. ( 1996 ) with some alteration. Briefly, the works infusion will be dispersed in ethyl alcohol to give 1A mg/ml of trial solution. An aliquot of 1A milliliter of trial solution will be diluted with 9A milliliter of distilled H2O. Afterwards, 200A I?l Folin-Ciocalteu reagent and 600A I?l of 2 % Na carbonate are added. The mixture is allowed to stand for 2A H at room temperature before the optical density was measured spectrophotometrically at 750A nanometer. Gallic acid is used as the criterion for the standardization curve. Entire phenolic content of the sample will be expressed as Gallic acid tantamount concentration ( mg/ml ) .
3.6 Determination of entire betacyanin content in samples
Absorbance values of samples are measured utilizing a spectrophotometer at 538 nanometers against a space of Standard Distilled Water ( SDW ) . The optical density obtained is so used to cipher the entire betalain concentration utilizing following expression ( Herbach et al. , 2007 ) .
A = Optical density
DF = Dilution Factor
MW = Molecular weight of betanin ( 550 g mol-1 )
= Molar extinction coefficients ( 60,000 L mol-1 centimeter in H2O
cubic decimeter = Path length of cuvette = 1 centimeter
3.7 Ferric cut downing antioxidant possible check ( FRAP )
The ability to cut down ferrous ions will be measured utilizing a method described by Benzie and Strain ( 1996 ) and Wong, Leong, and Koh ( 2006 ) , with little alteration. An aliquot ( 200Aµl ) of sample infusion will add to 3 milliliter of FRAP reagent ( 10 parts of 300 millimeters sodium ethanoate buffer at pH 3.6, 1 portion of 10 millimeters TPTZ solution and 1 portion of 20 millimeter FeCl3. 6H2O solution ) . The 300 millimeter ethanoate buffer will be prepared by blending 3.1g of Na ethanoate trihydrate ( C2H3NaO2_3H2O ) with 16ml glacial acetic acid and brought to 1 L with distilled H2O. The TPTZ solution will be prepared by doing a solution of 10mM TPTZ in 40 millimeter HCl. The reaction mixture is incubating at 37oC in H2O bath for 30 proceedingss. The addition in optical density at 593nm is measured. The antioxidant capacity based on the ability to cut down ferrous ions of the infusion is expressed as Aµmol Trolox tantamount per g of fresh weight.
3.8 Color Measurement
The colour of dried pulverization and fresh Peel will be utilizing a Hunter Colour Measuring System ( Labscan, XE, Hunter Lab. Inc. , USA ) .
3.9 Water Activity of dried Peels
AquaLab Series 3 Water Activity Meter will be used to find the H2O activity of the samples.