Malays. Appl. Biol. (June 2003) JZ(l):
NUCLEAR MAGNETIC RESONANCE STUDIES OF WATER PROPERTIES IN BREADED, FRIED CHICKEN BREASTS
''MASKAT, M.Y. and 2KERR, W.L.
'Food Science Program, School of Chemical Sciences and Food Technology
Faculty of Science and Technology, Universiti Kebangsaan Malaysia
43500 UKM Bangi, Selangor, Malaysia
2Department of Food Science and Technology The University of Georgia, Athens, GA 30606, USA
ABSTRACT
The effect of different breading particle size on water properties of breaded, fried chicken breasts was investigated using proton ('H) nuclear magnetic resonance (NMR). Breading was divided into three categories namely, small (particle size < U.S. No. 60 sieve), medium (particle size between U.S. No. 20 and U.S. No. 60 sieve) and large (particle size > U.S. No. 20 sieve). Chicken breasts were battered, breaded and deep-fat fried for 240 sec. at an initial temperature of 160°C. Samples were divided into coating, surface and middle regions. The water properties were assessed through moisture content, spin-lattice (Ti) relaxation time, spin-spin (T2) relaxation time and self-diffusion coefficient (D). In the surface region, all the NMR parameters decreased with increasing breading particle size used to form the coating. A bi-exponential model used to fit the Tt relaxation time data suggested the existence of a lower mobility water state (TISL) and a higher mobility water state (T1SH) in the surface region. T1SL decreased while T1SH increased with increasing breading particle size used for the coating. Reduction in NMR relaxation times was most likely due to the decrease in coating barrier property to moisture migration with the use of larger breading particle size.
ABSTRAK
Kesan saiz partikel reroti yang berbeza terhadap ciri lembapan bagi dada ayam yang telah disalut dan digoreng telah diselidiki menggunakan resonan magnetik nuklear (NMR) proton ('H). Reroti dibahagikan kepada tiga kategori, iaitu, kecil (saiz partikel < tapisan U.S. No. 60), sederhana (saiz partikel diantara tapisan U.S. No. 20 dan U.S. No. 60) dan besar (saiz partikel > tapisan U.S. No. 20). Dada ayam telah disalut dengan reroti dan digoreng selama 240 s pada suhu permulaan gorengan 160°C. Sampel kemudiannya dibahagi kepada bahagian salutan, permukaan dan tengah. Ciri lembapan dinilai berdasarkan kandungan lembapan, tempoh relaksasi spin-latis (Tj), tempoh relaksasi spin-spin (T2) dan koefisyen penyerapan (D). Pada bahagian permukaan, kesemua parameter NMR berkurangan dengan peningkatan saiz partikel reroti yang digunakan untuk penyalutan. Suatu model dwi-eksponen yang digunakan untuk memuatkan tempoh relaksasi Tt memberikan kemungkinan kewujudan keadaan lembapan yang rendah mobiliti (TISL) dan yang tinggi mobiliti (TISH) pada bahagian permukaan. T1SL berkurangan tetapi TISH meningkat dengan peningkatan saiz partikel reroti. Pengurangan tempoh relaksasi mungkin disebabkan oleh pengurangan ciri rintangan salutan terhadap perpindahan lembapan apabila reroti dengan saiz partikel yang lebih besar digunakan.
Key words: water properties, nuclear magnetic resonance, frying.
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