Impact analysis of different chemical pre-treatments on colour of apple discs during drying process

Transcription

1 Crot. J. Food Si. Tehnol. (29) 1 (1) Impt nlysis of different hemil pre-tretments on olour of pple diss during drying proess D. Mgdić *, Jsmin Lukin, Stel Jokić, F. Ččić-Kenjerić, M. Bilić, D. Velić University of Josip Jurj Strossmyer in Osijek, Fulty of Food Tehnology Osijek, F. Kuhč 2, 31 Osijek, Croti Summry originl sientifi pper The min purpose of this study ws to ompre olour hnges of hemilly pre-treted dried pple diss. Chnges were oserved y hrommeter in L * * * olour model y using Minolt hrommeter CR-4 nd y imge nlysis system in RGB olour model. Apple diss vriety "Gold Rush" were pre-treted nd dried in lortory try drier t drying temperture 7 C nd t irflow veloity of 1.5 ms -1. Different hemil pre-tretments were pplied on pple diss (dipping in.5% sori id solution;.3% L ysteine solution;.1% 4 hexyl resorinol solution nd 1% sodium metisulphite solution). Men vlues of olour prmeters, olour hnges nd orreltion oeffiients for pple diss were lulted for oth olour models. The nlysis showed sttistilly signifint influene of pre-tretment method on totl olour hnges for oth hosen olour models of dried pples. Clulted orreltion oeffiient etween olour hnges for used models ws found to e.894. Aording to olour hrteristis the est results were hieved when smples were pre-treted with.5% sori id solution. Aording to lulted results it ws found tht imge nlysis method s well s olorimetri method n e used to oserve the olour hnges on dried pple diss. Keywords: Pre-tretment, Colour, RGB, L * * *, Gold Rush Introdution In the pst few yers omputer vision ws rpidly developed nd imge proessing method tody hs n importnt role in the development of food qulity ssessment (Jelinski et l., 27). In omprison to erlier used trditionl methods, using digitl mer nd softwre for imges proessing proved to e n idel omintion for quikly, heply nd urtely olour mesure of vrious food produts (Ym & Ppdkis, 24). The most often used model is the RGB olour model. At this model eh sensor seprtely ptures the light intensity of the red (R), green (G) nd lue (B) olour hnnel respetively (Ktherine Leon et l., 26). These tehnique n e pplied on oth sides of pple (reddish nd greenish) nd gives more ojetive results thn hrommeter euse lmost 1% of pple surfe is ptured in n imge (Mgdić & Doričević, 27). Colour hnge is mostly used y the phenomenon lled rowning. Good knowledge of the rowning retion offers lots of wys to prevent these retions or to slow the sme one down (Gonzlez Aguilr et l., 24; Fernndez et l., 25). Aording to legl issues of food industry, sori id is good sustitute for sulphites to prevent rowning of fruits nd vegetles (Son et l., 21). Along with sori id good results in preventing rowning provided the sulphur tht ontining mino id groups. Cysteine, the olourless onjugte ompounds, is the est known representtive of these groups. It rets with quinone nd thus preventing enzymti rowning (Son et l., 21; Guerrero Beltrn et l., 25). Among the reently disovered sustnes tht prevent enzymti rowning, it is neessry to point out the 4-hexyl-resorinol whih hs een known s very suessful PPO inhiitor, espeilly with the pple produts (Son et l., 21; Iyidogn & Byindirli, 24; Guerrero Beltrn et l., 25). The im of this investigtion ws to determine nd ompre olour hnges of dried pple diss fter different pre-tretment methods using imge nlysis system nd hrommeter in RGB nd L * * * olour model, respetively. Mterils nd Methods Mterils Apple vriety "Gold Rush" ws hrvested t the smll lol fmily frm nd stored t +4 C. After pproximtely 2 minutes stiliztion t the mient temperture, pples were hnd peeled nd ut into diss, 2 mm dimeter nd 5 mm height. *Corresponding uthor; University of Josip Jurj Strossmyer in Osijek, Fulty of Food Tehnology Osijek, F. Kuhč 2, 31 Osijek, Croti; dmir.mgdi@ptfos.hr

2 Dmir Mgdić et l. / Impt nlysis of different / Crot. J. Food Si. Tehnol. / (29) 1 (1) Drying method Drying ws performed in pilot plnt try dryer (UOP 8 Try Dryer, Armfield, UK). The dryer (Fig. 1) is equipped with ontrollers for ontrolling the temperture nd irflow veloity. Air ws drwn into the dut through diffuser y motor driven xil flow fn impeller. In the tunnel of the dryer there were rriers for trys with smples, whih were onneted to lne. The lne ws pled outside the dryer nd ontinuously determined nd displyed the smple weight. Het power ontrol Drying ir thermometr Digitl lne Thermoouples to PC Air inlet Air outlet Fn speed ontrol Heters Door Trys Digitl nemometer Drying ir humidity sensor Fig. 1. Lortory dryer used for onvetive drying The drying temperture ws 7 C for oth, nontreted nd pre-treted pple diss nd the dryer ws operted t ir veloity of 1.5 ms -1. Before drying pple diss series were treted y dipping for five minutes with different solutions respetively s follows:.5% sori id solution; in.3% L ysteine;.1% 4 hexyl resorinol nd 1% sodium metisulphite. After five minute dipping in prtiulr solutions diss were removed out nd exess liquid ws left to dry nturlly. Apple diss on trys were pled into the tunnel of the dryer nd the mesurement strted from this point. The "Testo 35" proes, pled into the drying hmer, were used to mesure drying ir temperture. The digitl lne (Ohus, Explorer, USA) nd the digitl nemometer (Armfield, UK) were used for reording weight loss of smples nd irflow veloity in the five minutes intervl during drying proess. Dehydrtion lsted until moisture ontent of out 12% (wet se) ws hieved. Determintion of dry mtter ontent Dry mtter ontent of pple smples ws determined y drying milled smples (~1 g) t 15 ±.5 C to onstnt mss. Anlyses were done in duplite nd the verge dry mtter ontent (w d ) ws expressed in perentge (%) nd lulted using the following eqution: m 2 w d(%)= 1 m1 (1) where m 1 is the mss of pple smples efore drying (g) nd m 2 is the mss of pple smples fter drying (g). Colour mesurements The olour hrteristis were used s qulity prmeter of dried pple diss. Colour mesurement ws done using Minolt CR-4 Chrommeter nd imge nlysis system. Dt were stored in L * * * nd RGB olour models nd olour hnges during this period were evluted. The totl olour differene in L * * * olour model ws lulted s follows 2 * * * * * * ( ) ( ) ( ) E 2 2 * * * = L L L + + (2) Prmeter L * refers to the lightness of the smples, nd rnges from lk (L = ) to white (L = 1). A negtive vlue of prmeter * indites green, while positive one indites red purple olour. Positive vlue of prmeter * indites yellow while negtive vlue indites lue olour. The Minolt CR-4 Chrommeter D65 lirtion plte ws used for lirtion. Experiments were replited five times for lter sttistis. 32

3 Dmir Mgdić et l. / Impt nlysis of different / Crot. J. Food Si. Tehnol. / (29) 1 (1) Also, olour hnges were followed y imge nlysis in RGB olour model. Bsi elements of the imge nlysis system shown in Fig 2. re lightening hmer (low voltge hlogen lmps with refletor provided illumintion of smple re of 76±5 Lux), digitl mer (Pnsoni Lumix DMC-FZ3) nd softwre for imge pre-proessing nd nlysis (IrfnView, Adoe Photoshop, Glol L Imge/2). Apple diss for imging were pled t 6 m from mer. 1. Lightning hmer 2. Light soure 3. Digitl mer 4. Bkground for smple 5. Smple for nlysis 6. Computer Fig. 2. Imge nlysis system All ptured imges were ropped on the sme size (4 4 pixels) nd were ontined full re of smples. Anlysis ws done on four smples in every tegory (36 imges in totl). Imges were stored, proessed nd nlyzed in itmp grphi formt with 8-it pllet (2 8 = 256 olours). This grphi formt stores informtion out olours in RGB-triplets for every pixel on the imge where red (R), green (G) nd lue (B) re intensities of mentioned olours in rnge from to 255. Progrm were lulted verge perentge of red (R), green (G) nd lue (B) olour on smple re. An verge shre of eh olour on smple surfe ws presented s the finl result. Colour hnges in RGB olour model were lulted s: ( ) ( ) ( ) E RGB = R-R + G-G + B-B (3) where R, G nd B indite olour prmeters of rw pre-treted pple diss. Men vlues of olour nd olour hnges were lulted for oth olour models. Sttisti nlysis Sttisti 7. (Stt Soft In., USA) ws used for dt nlyzing. One-wy nlysis of vrine (ANOVA) nd multiple omprisons (post-ho LSD) were used to evlute the signifint differene of the dt t p <.5. Men vlues nd stndrd devitions were lulted from five replitions. Results nd Disussion Results of the olour mesurement of dried pple diss for oth L * * * nd RGB olour model re shown in Tles 1 nd 2. Sttistil nlysis (ANOVA, post-ho LSD) showed tht pre-tretment method hd sttistilly signifint influene on ll prmeters nd olour vlues of dried pple diss for oth olour models, while only hnge of R prmeter (in RGB olour model) t dried pple ws not sttistilly signifint. 33

4 Dmir Mgdić et l. / Impt nlysis of different / Crot. J. Food Si. Tehnol. / (29) 1 (1) Tle 1. L * * * olour prmeters of dried pple diss smple L * * * NT 7.64 ± ± ± 1.26 AK 73.7 ± ± ± 2.7, LC 73.4 ± ± ±.89 4HR ±.89, -.68 ± ±.64, NB 79.3 ± ± ±.87,,, - groups whih differed sttistilly signifint (p<.5) from one to nother ording to different pre-tretment methods Tle 2. RGB olour prmeters of dried pple diss smple R G B NT ± ± ± 2.26 AK ± ± ± 1.61, LC ± ± ± HR ± ± ± 2.9, NB ± ± ± 1.72,,, - groups whih differed sttistilly signifint (p<.5) from one to nother ording to different pre-tretment methods Figure 3 shows totl olour hnges of dried pple diss fter different pre-tretment methods for L * * * olour model. The iggest hnges in L*** olour model were mesured on pple smples treted with L-ysteine while the smllest hnges were oserved on smples pre-treted with sori id. An ANOVA nlysis showed the existene of two groups whih differed signifintly (p <.5; post-ho LSD) ording to different pre-tretment method. The totl olour hnges in L * * * olour model were E L*** = Pretretment with sori id redues totl olour hnge in L * * * olour model up to 19.27%, with L ysteine 8.59%, with 4 hexyl resorinol 13.1% nd with sodium metisulphite 14.99% in omprison with non-treted pple smples. 1 9 EL*** (men ±SD) 8 7 6, 5 4 NT AK LC 4HR NB, - groups whih differed sttistilly signifint (p <.5) from one to nother ording to different pre-tretment methods Fig. 3. Totl olour hnges ( E L*** ) of dried pple diss fter different pre-tretment methods Figure 4 shows the totl olour hnges of dried pple diss fter different pre-tretment methods for RGB olour model. In RGB olour model the iggest hnges were mesured on smples treted with 4 hexyl resorinol while the smllest hnges were oserved on pple smples treted with sori id. An ANOVA nlysis showed the existene of three groups whih differed signifintly from one to nother (p <.5; postho LSD). The one group orresponded with nontreted diss, nother with diss pre-treted with sori id solution nd with sodium metisulphite solution, nd third one orresponded with diss pre-treted with L ysteine solution nd with 4 hexyl resorinol solution. The totl olour hnges in RGB olour model were E RGB = The pretretment with sori id redues totl olour hnges in RGB olour model up to 61.53%, with L ysteine 2.6%, with 4 hexyl resorinol 19.4% nd with sodium metisulphite 56.95% in omprison with non-treted pple diss. The orreltion oeffiient etween olour hnges for used olour models ws lulted to e t vlue of

5 Dmir Mgdić et l. / Impt nlysis of different / Crot. J. Food Si. Tehnol. / (29) 1 (1) ERGB (men ±SD) NT AK LC 4HR NB,, - groups whih differed sttistilly signifint (p <.5) from one to nother ording to different pre-tretment methods Fig. 4. Totl olour hnges ( E RGB ) of dried pple smples fter different pre-tretment methods Conlusions Colour hnges of dried pples diss were oserved pplying Minolt hrommeter (CR- 4) in L * * * olour model nd imge nlysis system in RGB olour model. An ANOVA nlysis showed sttistilly signifint influene of different pre-tretment methods on the totl olour hnges for oth hosen olour models. Aording to olour hnges the smllest hnges were found t smples pre-treted with.5% sori id solution. Pre-tretment with sori id redues totl olour hnge in L * * * olour model up to 19.27% while tht vlue in RGB olour model ws found to e up to 61.53%. Consumers selet their food in supermrkets sed on, primrily, visul pereption nd often this is the only diret set of informtion s reeived from the produt. Aording to the lulted results (high orreltion etween hosen olour models) imge nlysis method s well s olorimetri method n e used to oserve the olour hnges on dried pple smples. Aknowledgments This work ws finnilly supported y the Ministry of Siene, Edution nd Sports of the Repuli of Croti (sientifi projets No nd No ). Arevitions Referenes Fernndez, L., Cstillero, C., Aguiler, J.M. (25): An pplition of imge nlysis to dehydrtion of pple diss, Journl of Food Engineering 67, Gonzlez Aguilr, G.A., Ruiz Cruz, S., Cruz Vlenzuel, R., Rodriguez Felix, A., Wng, C.Y. (24): Physiologil nd qulity hnges of fresh ut pinepple treted with ntirowning gens, LWT 37, Guerrero-Beltrn, J.A., Swnson, B.G., Bros-Cnovs, G.V. (25): Inhiition of polyphenoloxidse in mngo puree with 4-hexylresorinol, ysteine nd sori id, LWT 38, Iyidogn, N.F., Byindirli, A. (24): Effet of L ystein, koji id nd 4 hexylresorinol omintion on inhiition of enzymti rowning in Amsy pple juie, Journl of Food Engineering 62, Jelinski, T., Du, C.J., Sun, D.W., Fornl, J. (27): Inspetion of the distriution nd mount of ingredients in psteurized heese y omputer vision, Journl of Food Engineering 83, 3 9. Leon, K., Mery, D., Pedreshi, F., Leon, J. (26): Color mesurement in L*** units from RGB digitl imges, Food Reserh Interntionl 39, Mgdić, D., Doričević, N. (27): Sttistil Evlution of Dynmi Chnges of Idred Apples Colour During Storge, Agriulture Conspetus Sientifius 72 (4), Son, S. M., Moon, K.D., Lee, C.Y. (21): Inhiitory effets of vrious ntirowning gents on pple Slies, Food Chemistry 73, Ym, K. L., Ppdkis, S. (24): A simple digitl imging method for mesuring nd nlyzing olor of food surfes, Journl of Food Engineering 61, NT AK LC 4HR NB non-treted pple diss sori id solution L ysteine solution 4 hexyl resorinol solution sodium metisulphite solution Reeived: My 15, 29 Aepted: June 8, View pulition stts