Mohd Asraf Mohd Zainudin
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Preferred name
Mohd Asraf Mohd Zainudin
Official Name
Mohd Asraf, Mohd Zainudin
Alternative Name
Mohd Zainudin, Mohd Asraf
Zainudin, M. A.M.
Main Affiliation
Scopus Author ID
55539687700
Researcher ID
AAV-4476-2020

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Combination of light and oxygen accelerates formation of covalent protein-polyphenol bonding during chill storage of meat added 4-methyl catechol

2021-01-01 , Mohd Asraf Mohd Zainudin , Jongberg S. , Lund M.N.

Plant polyphenols applied as natural antioxidant ingredients, are known to bind to cysteine residues on meat proteins. The aim of this study was to examine the effect of light exposure on the formation of cysteine-phenol adduct in meat added 4-methylcatechol (4MC), a model polyphenol, during storage through quantitative LC-MS/MS-based analysis. Cysteine-4-methylcatechol adduct (Cys-4MC) formation in meat added 1500 ppm 4-MC increased significantly (by 50%) when stored under light in oxygen at 4 °C for 7 days as compared to storage in the dark. This was reflected by a significant decrease in thiol concentrations in the same sample. Gel electrophoresis showed loss in myosin heavy chain (MHC), and a resulting increase in cross-linked MHC (CL-MHC) and larger protein polymers in samples added 4MC. Protein blots stained with nitroblue tetrazolium (NBT) showed intensive protein-polyphenol binding in the meat samples added 4MC, but no major differences between storage conditions.

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Effect of Different Drying Process on the Protein-Thiol Content and the Physicochemical Properties of Water-Extracted Rice Bran Powder

2023-06-09 , Kasman N.A.S. , Mohd Sharizan Md Sarip , Mohd Asraf Mohd Zainudin

The effect of drying process of the water extracted rice bran powder on the protein-thiol and physicochemical properties was investigated. The rice bran extracted was prepared with water as solvent at high temperature and pressure using the autoclave equipment (121 °C, 15 psi, and 20 min) before undergone drying method using either spray dryer (BṺCHI Mini Spray Dryer B-290, LABOGENE, Denmark) or freeze dryer (CoolSafe 4-15L Freeze Dryers, LABOGENE, Denmark). The water-extracted rice bran powder (WRBP) yield, protein-free thiol compound, physical and functional properties were analyzed. The protein-thiol concentration was quantified using the 5,5 dithiobis (2-nitrobenzoic acid (DTNB) method while protein concentration was directly measured at 280 nm by UV-Vis Spectrophotometer. This was followed by physical properties (water solubility) and functional properties (foaming capacity and stability, water and oil absorption capacity) analysis. The powder yield of freeze-dried WRBP (7.69 ±0.29%) was significantly (p<0.05) higher than spray-dried WRBP (4.43 ±0.24%). The protein concentration of spray-dried WRBP (4.02 ±0.36 mg/mL) was higher than freeze-dried WRBP (3.91 ±0.75 mg/mL). Meanwhile, freeze-dried WRBP (1.22 ±0.36 nmol thiol/mg protein) had a higher thiol concentration than spray dried WRBP (1.18 ± 0.30 nmol thiol/mg protein). However, both results were not significantly different (p>0.05) between the drying method. Spray-dried WRBP had significantly (p<0.05) higher solubility in water compared to that of freeze-dried WRBP with values 1.22 ± 0.21% and 0.63 ± 0.34%, respectively. Freeze-dried WRBP had higher water and oil absorption capacity. There was no significant difference (p>0.05) in foaming capacity and stability for both drying treatments. In conclusion, the drying method for WRBP production could significantly affect the WRBP physicochemical properties.

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