Identification Of Characteristic Aroma And Preparation Of Mutton Flavor

There are a variety of by-products of lamb (such as bones, tail oil and belly oil).However, the usage of these by-products is single due to lack of technology to producehigh-end products and weak effort to develop products. Currently, domestic mutton flavorsusually feel unnatural and the fragrance can only last for a short time. The characteristicflavor is often not obvious. These issues have seriously limited development of motton flavorsindustry. It is imperative to develop natural and high value added products. This study aims atupgrade of byproducts from mutton processing and tries to develop high quality naturalmutton flavors by processing by-products of mutton (i.e. bones and mutton tallow), such ascontrolled enzymatic hydrolysis of bones and oriented oxidation of mutton tallow foodprocessing technology based on the characteristic fingerprint of mutton flavor. The maincontents of this study are as follows:The characteristic fingerprint of mutton flavor based on SPME-GC-MS, GC-O andcluster analysis was prepared. The reliability of characteristic fingerprint of mutton flavor wasassessed according to similarity of the characteristic fingerprint and principal componentanalysis (PCA). The results showed that the proposed characteristic fingerprint can effectivelyevaluate the deviation of testing sample and qualified sample; in addition, a qualitativediscriminant model for different species of meat was developed by use of PLS-DA method.All correlation coefficients of predicted value and actual value of categorical variable fordifferent species of meat samples were above0.89. The samples were100%recognized.Analysis of samples that were not involved in model establishment showed that characteristicinformation of mutton flavors and PLS-DA discriminant analysis together were able toeffectively detect and accurately discriminate mutton and other meat products. In addition,adulterated samples can also be accurately identified. This study will provide a scientific basisand method for quality assessment of mutton, quality control and preparation of muttonflavors.Proper protease was filtered out according to degrees of hydrolysis (DH) and solublenitrogen content. Quadratic general rotational regression model was established for Alcalase(protease of sheep bones) and flavourzyme. The impacts of hydrolysates of sheep boneprotein (SBPH) with different DHs on mutton process flavors (MPF) products were examinedby sensory analysis and GC-MS-O analysis. The results were as follows: when protein SBPHwith different DHs were used as precursors, one or several sensory attributes were relativelystrong; MPF samples presented obvious mutton flavor and roasted smell at DH of25.92%;when DH was30.89%, MPF samples showed high degree of simulation and aftertaste sense.The experimental results demonstrated that SBPH as precursors can be used to producevarious active aroma substances when the DH was in the range of25.92%-30.89%. PLSRcorrelation analysis was conducted for total of36characteristic lamp flavor compounds andsensory data. The correlation analysis results also indicated that hydrolysates of sheep boneswith hydrolysis degree of25.92%-30.89%were the most appropriate substrate for Maillardreaction. The conditions for enzymatic process were as follows: after thermal treatment, the sheep bone meal (20%) was cooled down to55℃. pH vas adjusted to8.5. Alcalase (3000U/gprotein) was added to hydrolyze for3h-4h. Then, flavourzyme (3000-3500U/g protein) wasadded to hydrolyze for2.5h-3h.Chemical index of mutton tallow oxidation (PV, p-AV and AV) and compositions andcontents of all volatile compounds during thermal oxidation process in different conditionswere studied. The results showed that temperature and duration of oxidation greatlyinfluenced the compositions and contents of volatile compounds in mutton tallow. PLSRmodel was developed for each volatile compound and chemical index. The significantcorrelations between chemical index and specific volatile compounds were identified. Theunderstanding of mutton tallow oxidation process provides basis for oriented oxidationregulation of mutton tallow.Both of non-oxidized mutton tallow and oxidized mutton tallow were involved inMaillard reaction. The products were compared through sensory description and GC-MSanalysis. The results showed that oxidized mutton tallow was important to stimulate orstrengthen characteristic mutton flavor in the course of thermal reaction. The MFSs usingmutton tallow with different degrees of oxidation as precursor were strong in one or severalsensory attributes. MFS5prepared with mildly oxidized mutton tallow (S5) presented obvioustaste of mutton and fat, which was a high degree of simulation. The correlation analysisagainst response of electronic nose, sensory data and19kinds of important chemicals alsoindicated that the mildly oxidized mutton tallow, as precursor of Maillard reaction, cangenerate characteristic mutton flavor. The preparation of mildly oxidized mutton tallow wasas follows:100g mutton tallow was oxidized for3h at140℃with air flow rate of60L/h(h·100g). The P.V., A.V. and p-A.V. of mildly oxidized mutton tallow generated in suchcondition were287.61meq/kg·mutton tallow,5.11mg KOH/g and262.52, respectively.The impacts of different conditions on preparation of MPF by Maillard reaction wereinvestigated. The results indicated that pH, temperature and duration had significant impactson flavor of MPF samples. If the pH and temperature were too high or too low, or reactionduration was too long or too short, it was not conducive to flavor of MPF. In addition,uniform design was adopted to optimize the Maillard reaction system for preparation of MPFsubstrates. The integrants of substrates included: protease hydrolyzate of sheep bone(100.0g), cysteine (1.369g), alanine (0.2g), taurine (2.5g), thiamine (2.5g), glucose (4.0g),HVP(1.428g), oxidized mutton tallow(12.0g, PV287.61meq/kg、p-AV262.52、AV5.11mgKOH/g); The optimal reaction condition is as initial pH of6.5,125℃and180min. ThisMaillard reaction system can be used to prepare natural high-quality mutton flavors withobvious characteristic flavor, which provided reference for development of byproducts frommeat processing.