Drying method

ingredient interactions and hence different water binding characteristics.

It was observed that at fixed microwave powers increase of halogen lamp power did not affect the water binding capacity and similarly microwave power was not effective on water binding capacity at fixed halogen lamp powers (Fig. 6). However, it would be expected that samples sub-jected to infrared-assisted microwave drying would have similar trends like the ones subjected to microwave dry-ing due to the fact that microwave mechanism was found to be the dominant mechanism previously. Therefore, it is difficult to explain the individual contributions of both microwave and infrared drying to water binding capacity when the two drying mechanisms were combined since rather than followable trends slight fluctuations were en-countered in infrared-assisted microwave drying.

All of the different methods of drying (microwave, in-frared, infrared-assisted) were effective to increase the wa-ter binding capacity of bread crumbs as compared to con-ventionally dried bread crumbs (Figs. 4–6). However, as long as color was concerned microwave-dried bread crumbs were lighter and infrared-dried bread crumbs were darker than conventionally dried ones (Figs. 1 and 2). On the other hand, _E values of most of the infrared-assisted microwave-dried bread crumbs were not significantly dif-ferent from conventionally dried ones (Fig. 3). Therefore, infrared-assisted microwave drying which reduced conven-tional drying time significantly can be selected as the best method for bread crumb production. In order to determine the optimum processing condition in infrared-assisted mi-crowave drying _E values, water binding capacity of bread crumbs and reduction of conventional drying times were considered (Figs. 3 and 6; Table 1). Bread crumbs pro-duced at 70% microwave and 70% halogen lamp, 50% microwave and 50% halogen lamp and 50% microwave and 30% halogen lamp power were the best conditions giv-ing bread crumbs with the highest water binding capacity and acceptable color while reducing the processing time significantly. As long as energy saving is concerned 50% microwave and 30% halogen lamp power can be selected as the optimum condition for bread crumb production.

Conclusions

Microwave, infrared and infrared-assisted microwave dry-ing shortened the drying time significantly with respect to conventional oven drying. The drying time was found to de-crease with increase in power (microwave and/or halogen lamp) in all of the drying treatments.

Microwave drying caused lower _E values and infrared drying resulted in higher _E values with respect to conven-tional oven drying. However, most of the infrared-assisted microwave-dried bread crumbs had similar color value with the conventionally dried ones. Significant effects of both microwave and halogen lamp powers on color change were not observed.

All of the three drying methods, microwave, infrared and infrared-assisted microwave drying, caused significant dif-ferences in the water binding capacity of the bread crumbs when compared with the conventional oven drying. As microwave power increased, water binding capacity in-creased in microwave drying, however, effect of halogen lamp power was not significant on water binding capac-ity in infrared drying. At fixed microwave (halogen lamp) powers increase of halogen lamp (microwave) power did not effect the water binding capacity in infrared-assisted microwave drying.

As a result, infrared-assisted microwave drying can be recommended to be used for production of bread crumbs since bread crumbs obtained by this method were accept-able in terms of color and water binding capacity and con-ventional drying time was significantly reduced.

References

1. Dyson D (1990) In: Kulp K, Loewe R (eds) Batters and breadings in food processing. American Association of Cereal Chemists Inc., Minnesota, USA, pp 143–152

2. Suderman DR, and Cunningham FE (1983) Batter and Breading Technology. AVI Publishing Co., Westport, CT

3. Datta A K, Ni H (2002) J Food Eng 51:355–364

4. Sumnu G, Turabi E, Oztop M (2005) Lebensmittel Wissenschaft und Technologie (in print)

14

5. Baysal T, Icler F, Ersus S, Yıldız H (2003) Eur Food Res Technol 218:68–73

6. Beaudry C, Raghavan GSV, Ratti C, Rennie TJ (2004) Drying Technol 22(3):521–539

5. Feng H (2000) Microwave drying of particulate foods in a spouted bed, Ph. D. Thesis, Washington State University, Washington

5. Funebo T, Ohlsson T (1998) J Food Eng 38:353–367

6. Harrison DL (1980) J Food Protect 43(8):633–637

7. Krokida MK, Maroulis ZB (1999) Drying Technol 17:449– 466

5. Maskan M (2000) J Food Eng 44:71–78

6. Medcalf DG, Gilles KA (1965) Cereal Chem 42:558–567

7. Datta AK (1990) Chem Eng Progr 86:47–53

8. Lin TM, Durance TD, Scaman CH (1998) Food Res Int 4:111–117

15. Goksu EI, Sumnu G, Esin A (2005) J Food Eng 66:463–468

16. Nowak D, Lewicki PP (2004) Innov Food Sci Emerg Technol 5:353–360

15. Feng H, Tang J (1998) J Food Sci 63(4):679–683

16. Keskin SO, Sumnu G, Sahin S (2004) Food Res Int 37:489–495

17. Demirekler P, Sumnu G, Sahin S (2004) Eur Food Res Technol 219(4):341–347

15. Demirekler P (2004) Optimization of microwave-halogen lamp baking of bread. MS Thesis, Middle East Technical University, Ankara

15. Tan M, Chua KJ, Mujumdar AS, Chou SK (2001) Drying Technol 19(9):2193–2207

15. Puotto P, Puolanne E (2004) Meat Sci 66(2):329–334

16. Fennema OR (1996) Food chemistry, Dekker, New York

17. Puolanne E (1999) Proc 45th Int Cong Meat Sci Technol 116–120