Effect of Microwave Power and Time on Total Phenolic Contents and Antioxidant Characteristics of Microwave Assisted Extracts of Watermelon Rind Powder Microwave Assisted Extracts of Watermelon Rind Powder

Watermelon is gaining importance as a functional food due to its therapeutic effect. The therapeutic effect of watermelon has been reported and has been attributed to antioxidant constitutes. The major component in watermelon rind is citrulline that has a strong antioxidant effect which protect body from free-radical damage. Objective: This study was conducted to investigate the effect of microwave powers (150 W, 300 W & 450 W) and time intervals (1, 3 & 5 minutes) on total phenolic content (TPC) and total flavonoid content (TFC) and antioxidant characteristics i.e. DPPH and ferric reducing antioxidant potential (FRAP) of microwave assisted extracts of watermelon rind powder. Methods: The extracts collected after Microwave assisted extraction (MAE) of watermelon rind wereanalyzed for their antioxidant potential through different tests including total phenolic contents (TPC), total flavonoid content (TFC), DPPH assayand FRAP. Results: Microwave assisted extraction by using ethanol as a solvent at different microwave powers and various time intervals showed that total antioxidant potential was significantly higher at low microwave power such as TPC ranges obtained at 150W for 1, 3 & 5 minutes of time intervals show ranges (159.84, 160.04 & 169.71 mg GAE/100 g). While TFC ranges at 150W for time 1, 3 & 5 minutes were (21.31, 24.15 & 42.20 mg CEQ/100g) whereas DPPH ranges at 150W for time 1, 3 & 5 minutes were (53.14, 54.87 & 68.17 % ascorbic acid inhibition) and FRAP values at 150W for time 1, 3 & 5 minutes were (201.71, 221.50 & 326.43 mg FE/100g). While high microwave power 450W can result in disruption of some antioxidants at various time intervals. Conclusions: Watermelon rind is a rich source of many antioxidants andmicrowave assisted extraction technique should be implemented in the food and nutraceutical industries and microwave assisted extracts of watermelon rind should be utilize for the development of new functional food to combat many health related problems

Design, Fabrication and Performance Evaluation of an Agro-Dryer for Drying Agro-Commodities

Muhammad Saleh Soomro Ph.D. Power and Machmery Engineering "Design. Fabrication and Performance Evaluation of an Agro-dryer for Drying Agro-commoditles" "7ne pUf:JOS€ Of thiS stuay vIas to aeslgn faoflcate anc les: a~ ag~''" C0-''''''· tor crvlng a9ro-commodltles in.tlailY a surve~'' was cona~clea lO IQam,;) vmlC:1 CQr:1mOOltles are arlea loca~r} ana \''.'',a~ r:1e:i1QCS were aoomec Ir ej ..... ,'':ng Thereafter a:ye~ aeSlgns Ir use Ir, vanous Dans of tne world were r,o~v,ewed and a su:tab!e deslg:l was selectee ~or 1tle DfotOiyoe Mal eOl1ohasls was given In oeSlgnlng a Simole macnlr.e to De maae from loca!" availaoie malenalS ana manufact<...!nng technology Iriormatlon gathered '':or. 200 respondents tndlcaieo tha: local-y'' cerea~s_ iegU:719S conOlmeniS fruits. vege:anies medicinal pial"lts. hay ana fodder TISi: ana mea: are arlec mostiy ;.., eDen air or uncer snade Ooen air-drying was repOilea as tne mos: ~'')mmon metlloa of orylng agro-commooltles T1e :armers were nOt na:)p,'' .v~t~ uncontroileo open ai'' methoo a~: aeslred 1.e ces''~., a Slm:)le a'',c easy to 50''- law cost dryer sur;C1n!e j.;)r 0,\'':n·1 2''1Y agrO-C~)f;1:''10dl:y H'' a ("'':e8:'' or clau,:y ~ "''y aav A orOWlype drier v.as aesr'':::''1€:: rna: l:se:J D":"''" a.rect ana Inc re:c:: 50,a IE:'': II· conJL: c;lon vn:1 a :), IV:S~;:i ":G~ c~yl;; ;"''"''·3:e-2:s \ViP"'' S,- ''-~;o::::ts , .. .In:je~ II -:;;:ne;l~ weather CO:1ClI:lons 11ltia:1y t~e c·:.-·er v:as ;e5!ed Unoei three drYlfl" :-"''""IC·'':::~S \'' orye. alone til) Orye~ \\·Fl DOQSter El1:) 1111) open alr<Y·~·ln:::: 3.~ :or~rOi) on Chilies and rase f10\"2~S Results lno.catea :ha: d~yer-:)oQsti r <,;omDlnailon removed tne prod~;G rlOIS:>JrE- very CJlckly fo!''c\.'':ea by c-Yt=.: 1Io:''c w:111e open alf took double the orylng :''.r""1e as compared to dryer r:lodes HaVing gamed ine confide~ce on the cry·;:::- performance ce:3!ied tes.ts /I,=~e conaucted to stuay me e--:e.::::s ct lOur ary:ng modes dryer alone driEr DOaSter charcoal heating and open air forced air convection [at night] ~r3y sr.I''Ilng and material layer Inlckness on Ihe oryer pertormance Tes:~ Ind:cated that drier alone removed 1 6 to 3 OC/~ mOlst>Jre/hour f~orr Chili ~ C8:;..llflower and green peas as CO:Toare-: iO Jt..:S~ '' ... ~ per hour In open a:r However f~am rose flowers 5-1 OS~ mlhr was removed In dryer mode wt"l, E c:·~n-Cllr moae removed 3-''h~ m/nr Thus the a~lng time reqUired IP C:""'',£": modes was more Of less half of that requlrec In op~n-alr C''Ylng Dryer modes unde, 7:)!"";:::ed air convection [at nlgnt: remov~; s:;n,:,cantly more mOisture compared to open-air moce Shifting of liS,. ~ however hao no significant effect In !irS; iWO aays but on third ana "ourt/1 c;;;:. the e7iect was slgmflcant. MOisture removed from ::llck layer of commod.:.~<" unoer forced air convection In d;yer moces Vias Significantly higher pc: cOr:1~ared to open-air mode Charcoal heating was as effective as the soia: drymg 90 kg of vegetables were dned uSing one oag Of charcoa'' oay In A days Calculations on me calorific value and drying efficiency confirmed tnat G kg charcoal would deliver 5 3 M~I of energy I hour and a 40 kg bag of charcoal was enougn for one day The farmer may use thiS option on a rainY or clouoy oay In a s;ackea lray arrangement tne too trays cried Significantly fasle~ lIlan tne trays ola::eo 0810W t~e tOP trays I; was oeservec rna: In a StacK 0'' G trays tne top tray removed 36% secane tray ''11.>,; 8r''lC tnlrd trav 41:i. more mo!sture comoarea to tne ::-8,. placeo a: !ne Doner Cnilles a: full load wnen orled In aDen-ali reO''Jlreo 40°,.: more [lme as com oared [0 the aryer mooes A: P811 load open alr-arylng [Ook "''75 10 -;33°,,., more time 2S comparee to dryer modes In rose flowers 100% more time was requlrea In aDen al~-orylng tnan the aryer-boosle~ mode Cauliflower when Cried In ooen al;" required 50% more time under natural air canveC[1on ano 100% more time In forced air convection as comparec to oryer mode Similar treno was nmea In green Deas ana cniiles In StaCK tests MOisture removal !rom Chilies CGullfiower and green peas 0/1 dally baSIS Indicated tna: cUr.1ulauvely 40°''0 mOisture escaped on first day 69% on second day ana 89% on third day In aryer modes wnereas 30''/0 on firs: day 56% on secona cay and 76% on third Gay In open-air aryln;: mace Thus the drye~ moaes remov9G slgmficantly mo~e mOisture than tne open·al~ mode The temDerature Inside the dryer at high mOisture ratio was less due ;:0 heavy mOisture load InSloe the dryer As tne mOisture raIlO staned dec:-easil''lg wltn progress In o''Ylng process mus the te~pe:-ature SimultaneouslY energized tne d-Ylng process Conversely tne rela:''ve humidity remained h''gr 1:151de rhe dryer at higher mOisture ratiO As the drymg process progressed the mOisture ratio decreasea and consequentlY the reiatlve humidity oroopec.; sharply to a minimum, Temperature and humIdity snowed a Similar respons~ In green peas and chilies The ratmg of organole:::>tlc marenals dried In dryer With solar or charceal heat was between good and excellent while the matenals aned In open air were rated betvveen poor and fair Two models were developed to predict the rate o~ mOisture removal With crying time The empIrical model based on the mOisture removal - time relationship yielded predication eauatlons of logantnmlc form that best fitted t,- the expenmental values with R2 ranging from 091 to a 99 Another mathematIcal model usee mOisture rs:io - time relationship. also Yielded prediction ecuatlons of exponenllal form that also very accurately matchea WIth the exoenmental results With R2 approaching unity A Simple dryer deSIgn IS suggested for farmers WIth babul wood frame and a polyetnylene shee: transparent cover The cost of the suggested dryer IS affordaole. ensuring a better product qt.:atlty