Studies On The Preparation Of Pork Flavors By Thermal Reaction

The aim of this paper is to prepare the natural pork flavors closely resembling the taste and aroma of natural pork meat by the thermal reaction.Firstly, different enzymes (Flavourzyme, Protamex, Neutrase and Papain) were used individually and two among them Flavourzyme and Protamex were selected after preliminary tests as the best one, then they were used in combination based on their degree of hydrolysis (DH). The optimum amount of were 18 (LAPU/g protein) and 0.045 (AU/g protein) corresponding to Flavourzyme and Protamex, respectively. The design and optimum hydrolysis conditions of enzyme combination were investigated with response surface methodology (RSM). The optimum concentration of substrate , temperature and initial pH were 7.5%, 49℃ and 7.0, respectively. Hydrolysis was carried out at optimum conditions of 8 hours, DH reached 51.08%.Secondly, the reactants of simple model thermal reaction were selected by monofactorial test and sensory evaluation. The optimum reaction conditions were investigated using orthogonal design and response surface methodology. Reaction products of simple model thermal reaction were evaluated by sensory evaluation, solid phase microextraction(SPME) and gas chromatography-mass spectrometry(GC-MS). The results showed that simple system was satisfying. The optimum operation parameters of simple model thermal reaction were following: glucose, thiamin, pork oil and cysteine with a weight ratio of 2:1:1:2, and the same level of water as the reactants, reaction temperature 110℃, reaction time 1 hour, initial pH 6.0.Finally, on the basis of the two results obtained above, studies on the system containing enzymatically hydrolyzed pork and the simple model thermal reaction were investigated sensory evaluation. The degree of hydrolysis had no direct proportion with overall flavors of the system, and the hydrolysis time around 4 to 6 hours could make best contribution to the overall flavors of the system.In addition, according to the application experiment, sensory evaluation, solid phase microextraction(SPME), simultaneous distillation and extraction and gas chromatography-mass spectrometry(GC-MS), the pork flavors obtained under the optimum conditions could be mixed with other ingredients, and gave some satisfying and everlasting aromas and odour. The results showed that some identified compounds were identical with the published ones. Especially the compounds: 4-methyl-5-thiazoleethanol, 2-methyl-3-furanthiol, 2-acetylfuran and (5-methyl-2-furyl)-methylsulfur etc.