Abstract
The study focuses on evaluation of the impact of moisture on the relaxation characteristics obtained through uniaxial compression of single wheat kernels. Polish soft wheat (c.v. Emika) at eight different moisture levels. i.e. 8, 10, 12, 14, 16, 18, 20, and 22% (wet basis) was used in the research. The experiments were made with the help of a Zwick Z020 universal machine. Individual wheat kernels were compressed with constant load value of 50 N between two flat plates. Relaxation time was equal to 300 seconds. Values of the relaxation decay parameter Y(t) were established for the determined relaxation time. Parameters k1 and k2 for the model presented by Peleg and Normand were also calculated. Compression work and deformation increased with the moisture rise from 5 to 25 mJ and 0.2 to 1.0 mm, respectively. An increase of kernels moisture caused the load at relaxation time as well as the decay parameter Y(t) to decrease. The values at 22% moisture were more than two times lower that corresponding 8% water level. Coefficients k1 and k2 decreased from 3.5 to 1.5, and from 53 to 13, respectively. A linear relation between the two model coefficients was observed. The impact of kernel moisture on the analyzed parameters was described in the form of regression equations.
References
- Bargale, P.C., Irudayaraj, J., Marquis, B. (1995). Studies on rheological behaviour of canola and wheat. J. Agric. Eng. Res., 61, 267–274.
- Bhattacharya, S., Narasimha, H.V., Bhattacharya, S. (2006). Rheology of corn dough with gum arabic: Stress relaxation and two-cycle compression testing and their relationship with sensory attributes. J. Food Eng., 74(1), 89–95.
- Brujić, J., Johnson, D., Makse, H.A., Sindt, O. (2005). Granular dynamics in compaction and stress relaxation. Phys. Rev. Lett., 95, 128001.
- Cespi, M., Bonacucina, G., Misici-Falzi, M., Golzi, R., Boltri, L., Palmieri, G.F. (2007). Stress relaxation test for the characterization of the viscoelasticity of pellets. Eur. J. Pharm. Biopharm., 67(2), 476–484.
- Figueroa, J.D.C., Manuel, C.I., Hernández-Estrada, Z.J., Ramírez-Wong, B. (2012). Stress relaxa-tion of wheat kernels and their relationship with milling, rheological, and bread making quality of wheat. Cer. Chem., 89(4), 211–216.
- Hernández, Z.J.E., Figueroa, J.D.C., Rayas-Duarte, P., Martínez-Flores, H.E., Arámbula, G.V., Luna, G.B., Peña, R.J. (2012). Influence of high and low molecular weight glutenins on stress relaxation of wheat kernels and the relation to sedimentation and rheological properties. J. Cereal Sci., 55(3), 344–350.
- Karim, A.A., Norziah, M.H., Seow, C.C. (2000). Methods for the study of starch retrogradation. Food Chem., 71, 9–36.
- Khazaei, J., Mann, D. (2004). Effects of temperature and loading characterictics on mechanical and stress-relaxation behavior of sea buckthorn berries. Part 3. Relaxation behavior. Agricult. Engin. Internat.: the CIGR J. Sci. Res. Develop., VI.
- Lewicki, P. (2004). Water as the determinant of food engineering properties. A review. J. Food Eng., 61(4), 483–495.
- Lewicki, P., Jakubczyk, E. (2004). Effect of hot air temperature on mechanical properties of dried apples. J. Food Eng., 64(3), 307–314.
- Lewicki, P., Spiess, W.E.L. (1995). Rheological properties of raisins: Part I. Compression test. J. Food Eng., 24(3), 321–338.
- Lewicki, P., Wolf, W. (1995). Rheological properties of raisins: Part II. Effect of water activity. J. Food Eng., 26(1), 29–43.
- Lewicki, P., Łukaszuk, A. (2000). Effect of osmotic dewatering on rheological properties of apple subjectedto convective drying. J. Food Eng., 45(3), 119–126.
- Steffe, J.F. (1996). Rheological methods in food process engineering, 2nded. Freeman Press, East Lansing, MI, USA.
- Telis-Romero, J., Gabas, A.L., Sobral, P.J.A. (2004). Osmo-convective drying of mango cubes in fluidizedbed and tray dryer. Drying 2004, Proceedings of the 14th International Drying Sympo-sium São Paulo, Brazil, C, 1868–1875.
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