Research And Application Of Attractants Prepared By Different Protein Sources

The attractant is a kind of flavor additive to improve the palatability of dog feed,which usually can effectively stimulate dog's appetite and increase feed rate.At present,the offal or meat of animal is mainly used as protein source of attractant.However,other raw materials were rarely reported as protein sources for the preparation of attractant.In this paper,chicken liver,Lentinula edodes and Tenebrio molitor were used as three varies of protein sources.Firstly,response surface methodology with hydrolysis degree as indicators was used to optimize the enzymatic hydrolysis process of three proteins.Secondly,three different dog feed attractants were prepared from three kinds of proteolytic hydrolysates.Gas chromatography-mass spectrometry(GC-MS)and palatability tests were carried out.The key volatiles affecting the feeding preference of dogs were analyzed by partial least squares regression(PLSR).These key substances were added to the attractant and verified by palatability test.Furthermore,pet feeding sustained-effects,fecal and gut microflora of dogs were detected to analyze effects of three protein attractants on pet feeding sustained-effects and gut health.The main research contents and results are as follows:The effects of temperature,time,pH value,enzyme dosage and feed-liquid ratio on enzymatic hydrolysis of three protein sources were preliminarily verified by single-factor experiments.Then Plackett-Burman design was used to screen out the enzymatic hydrolysis factors with significant hydrolysis effect and Box-Behnken design was used to establish the response surface to optimize the parameters of enzymatic hydrolysis process.The top hydrolysis degrees of chicken liver,Lentinula edodes and Tenebrio molitor are respectively54.82 %,36.10 % and 30.14 %.Three kinds of protease hydrolysates were prepared with the same Maillard formula and process.There were all respectively 48 flavor substances from three attractants made of chicken liver,Lentinula edodes and Tenebrio molitor,which were detected by GC-MS with the extraction of headspace solid phase micro-extraction(HS-SPME)and simultaneous distillation extraction(SDE).The aroma activity value(OAV)was introduced as the indicator of aroma intensity.The palatability of the three kinds of feed attractants was compared through the two-bowls test.The results showed that the palatability of the chicken liver attractant was significantly better than that of the mushroom attractant and the yellowmealworm attractant,while that of the mushroom attractant was slightly better than that of the yellow mealworm attractant.The correlation between palatability and flavor substances was analyzed by using partial least squares regression(PLSR).The key volatile compounds affecting palatability were bis(2-methyl-3-furyl)disulfide,indole,methional,2-(methyl thio)phenol,?-butyrolacton,furfuryl alcohol,acetic acid and isovaleraldehyde.It's testified that the palatability of to Lentinula edodes and Tenebrio molitor attractant was significantly improved through adding bis(2-methyl-3-furyl)disulfide,indole,methional and 2-(methyl thio)phenol.Four groups of experimental dogs were fed with four kinds of dog feeds respectively supplemented with chicken liver attractant,Lentinula edodes attractant,Tenebrio molitor attractant and blank dog feed for 14 days.The results showed that there was no significant difference in feed intake among dogs eating feeds supplied with attractants from day 3 to day14,while feed intake of dog feed supplied with attractants was all significantly higher than that of the blank dog feed.Meanwhile,the fecal of the experimental dogs were collected and scored once every seven days since feeding test started.The scores were not significantly different.The quantity of Bifidobacterium,Lactobacillus,Escherichia coli and Clostridium perfringens abstracted from fecal were detected by means of plate counting method,which showed that Tenebrio molitor attractant and Lentinula edodes attractant could restrain the growth of Escherichia coli and Clostridium perfringens while significantly stimulate Bifidobacterium and Lactobacillus.However,chicken liver attractant had no obvious impact on regulating gut flora.In addition,the contents of short-chain fatty acids and lactic acid in the fecel of dogs fed with Lentinus edodes and Tenebrio molitor attractants increased significantly,which testified that Lentinus edodes and Tenebrio molitor could promote the beneficial microflora.