| By using chicken bone stock as the research object, through the research on the keytechnologies of chicken bone stock, including boiling process, concentrating process,homogenization process and sterilization process, and the study about the basic tastecharacteristics and the flavor components of chicken bone stock, the effects of key processeson the quality of chicken bone stock and the changes in the flavor attributes of chicken bonestock were investigated, so as to provide a theoretical basis for the industrial production ofchicken bone stock. The main results were listed as follows:1. The influences of bone sizes, solid-liquid ratio and different extraction methodsincluding the temperature and time regime on the quality of chicken bone stock wereinvestigated. And based on the study of single factors, boiling conditions was optimized byresponse surface method. The optimum boiling conditions were as follows: bone size of1cm,liquid-solid ratio of3:1, boiling method of high-voltage cooked at117℃for67min. Thedissolution ratio of total nitrogen of chicken bone stock obtained under the optimumconditions could reach69.18%, integrated sensory score was up to21.4points, whichindicated that the stock had the best nutrition and flavor.2. The influences of atmospheric and vacuum concentration on the quality of chickenbone stock were significant difference (p<0.05). Vacuum concentration was more favorable tomaintain the quality of the chicken bone stock; the two fat oxidation indexes, POV value,TBARS of the stock, were less than that obtained by atmospheric concentration, and thesensory score was higher. The optimum seasoning and diluting solutions were as follows: saltdosage of0.25%, sugar dosage of0.5%, flavor enhancer dosage of0.2%, the dilution ratio of1:6.3. Effects of contents of fat added, emulsifier HLB (Hydrophile Lipophylic Balance)value and contents, stabilizer formula, homogenization conditions on stability of chicken bonestock were investigated. The results showed that, the above factors had significant effects onthe stability of chicken bone stock. The emulsification system of chicken bone stock wasstable and had fine and uniform particles when the amount of fat added was about15%, theamount of composite emulsifier (HLB=10) added was around2.5%mixed by67.4%of sucrose ester-13and32.6%of3.8molecular distilled monoglycerides, the compoundstabilizer formulation: xanthan gum of0.25%、carrageenan of0.1%、β-dextrin of0.5%, andthe chicken bone stock was homogenized under20MPa of homogenization pressure at60℃for twice.4. The best thermal sterilization conditions of chicken bone stock was121℃/min(6-6-5). Under this condition, F value was about7.6min, and the product reachedpreservation requirements. The sensory quality score of the product was the highest, andminimum nutritional components (proteins, amino nitrogen and crude fat content) were lost.5. With storage time extending, various nutrients (soluble proteins, amino nitrogen andsoluble sugar) of chicken bone stock were destroyed gradually, but the loss ofaforementioned nutrients in sterilized chicken soup was significantly less than that in thechicken soup without sterilization (p<0.05) and changed more slowly during storage. Curvesof each nutrient during storage were different; soluble protein content in groups with orwithout sterilization showed a downward trend; the amino nitrogen content in sterilized groupincreased first and then decreased, while in group without sterilization it showed a continuousdownward trend; content of soluble sugar in two groups of chicken soup increased first andthen decreased with a maximum in the first weekduring storae. Meanwhile, the TVB-Nvalue、TBARS values and the total number of colonies of chicken bone stock during storagewere significantly decreased due to heat sterilization, and changes in the quality of chickenbone stock were delayed.6. The basic taste characteristics of chicken bone stock were umami, sweet andsalinetaste. Umami of the chicken bone stock showed a highly significant positive correlationwith free amino acids, nucleotides and oligopeptide content (p<0.01), and an obviouslypositive correlation with soluble sugar content (p<0.05). Sweet exhibited a very significantpositive correlation with soluble sugar content (p<0.01), and a significant negative correlationwith oligopeptide content (p<0.05). Salinetaste showed a significant positive correlation withNaCl content. Acidity had a significant positive correlation with oligopeptide content. Bittertaste exhibited a significant correlation with NaCl and oligopeptide content, but theastringency had no obvious correlation with each index content.7. Analyses of amino acid composition and content in3kind of chicken bone stocks showed that the total amino acid and free amino acid content in chicken bone stock cookedunder high pressure were significantly higher than that of chicken bone stock cooked undernormal pressure (p<0.05). Amongthe18kinds of free amino acids in stock there were7kindsof essential amino acids; threonine content was the highest followed by lysine. Free aminoacids, especially tasty amino acids Glu and Asp greatly contributed to the overall flavor ofchicken bone stock.8. By SPME-GC-MS, a total of71kinds of volatile compounds in three samples ofchicken bone stock were identified, including hydrocarbons, alcohols, aldehydes, esters,ketones, sulfur and oxygen-containing heterocyclic compounds. The relative content ofhydrocarbons, alcohols, aldehydes and oxygen containing compounds in three chicken bonestocks were higher and accounted for a large part of the total, but the relative content of acids,ketones and nitrogen compounds were much lower. The chicken bone stock cooked underhigh-pressure had more volatile flavor compounds than that of chicken bone stock preparedunder atmospheric pressure, of which48species were common to the three samples. Themain characteristic aroma of chicken bone stock were from hydrocarbons, carbonylcompounds and heterocyclic compounds, wherein the substances including hydrocarbon:pentane、1,3-oxa-bicyclo [10.1.0] tridecane and7-hexyl nineteen alkyl, alcohols:(Z)-3-nonylalcohol、1-hepten-3-alcohol and fifty carbon alcohol, aldehydes:(E,E)-2,4–decadienal、(E,E)-2,4–nonadiene、hexanal、(E,E)-2,4-dodecadiene aldehyde and (E)-6–nonenal, esters:palm methyl ester, heterocycles:2-pentyl furan and dimethyl disulfide, made greatercontributions to the characteristic flavor of chicken bone stock. |
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