Effects Of Fermented Tangerine Peel And Passionfruit Peel On Disease Resistance Or Chicken Flavor In Sanhuang Chicken

With the continuous improvement of people’s living standards,preferences of consumer are also changing,which has brought great development opportunities to China’s chicken market.Under the background trend of‘banning antibiotics’and‘limiting antibiotics’in livestock and poultry feed,how to improve the disease resistance of chicken and enhance chicken flavor has become current research focus.Tangerine peel is a by-product of citrus processing,and it is also a kind of traditional Chinese medicine.Its main functional component is flavonoids,which has various biological effects such as scavenging free radicals,antioxidant,antibacterial,antiviral and hypolipidemic effects.Passion fruit peel is a by-product of passion fruit processing.It has a unique aroma and has the aroma of various fruits.Applying both peels to the breeding of broilers is expected to improve their disease resistance and chicken flavor.However,due to its high content of crude fiber,it is not suitable for direct feeding,which can be solved by fermentation,and the fermented product may further enhance its antioxidant activity and increase peel flavor.Therefore,different combinations of Bacillus subtilis,Candida utilis and Lactobacillus plantarum were used here to ferment tangerine peel and passion fruit to establish the respective fermentation processes.Sanhuang chickens were used as experimental subjects to detect the disease resistance of tangerine peel fermentation products and the effects of passion fruit peel fermentation products on chicken flavor substances in order to provide a new strategy for improving the disease resistance and meat quality of chickens.1.Establishment of fermentation process for tangerine peel and effects of fermentation products on growth performance and disease resistance in Sanhuang chickensDifferent temperatures including 30°C,35°C and 37°C were designed here for the fermentation of tangerine peel,and the suitable fermentation temperature was screened by the number of viable bacteria in the fermented product.Then,the differences of total flavonoid content obtained by different ratios of strains（Bacillus subtilis:Candida utilis:Lactobacillus plantarum=1:1:1,1:1:2 and 2:1:3）,inoculation amount（5%,10%and 15%）and fermentation time（0-7 d）were compared,and the antioxidant properties of fermentation products were detected to further optimize the fermentation system of tangerine peel.Sanhuang chickens at the age of 30-40 days were selected for experiments,and 0%（control group）,300 mg/kg Vitamin C（Vit C）、2.5%、5%and 10%fermented tangerine peel were added to the basal diet,respectively.The growth performance,immune performance,antioxidant performance and anti-stress ability parameters were measured on 14 d,28 d and 42 d,respectively,to explore the effects of fermented tangerine peel on the disease resistance of Sanhuang chickens.（1）Under the condition of 35°C,Bacillus subtilis,Candida utilis and Lactobacillus plantarum at the ratio of 1:1:2 could grow in the fermentation substrate of tangerine peel;The content of total flavonoids in the 10%inoculation group increased by 2 times at 4 days of fermentation,which was significantly higher than that in the other inoculation groups（P<0.01）.As shown by antioxidant capacity test,the scavenging rate of DPPH free radical and ABTS free radical,as well as FRAP iron ion reduction ability were significantly higher than these of unfermented tangerine peel,respectively（P<0.05）.（2）After feeding with fermented product of tangerine peel for28 days,compared with the control group,the average body weight and daily gain of Sanhuang chickens in the Vit C,5%and 10%addition groups were significantly increased（P<0.01）,and the feed conversion ratio and daily feed intake were decreased（P<0.01）.（3）In terms of immunity,the spleen index and thymus index in 5%and10%fermented tangerine peel groups were significantly higher than these in Vit C treatment group,2.5%fermented tangerine peel group and control group（P<0.01）.The contents of Ig A,Ig M and Ig G in 10%fermented tangerine peel group were significantly higher than those in control group and other treatment groups（P<0.01）.After feeding for 28 days,the content of serum C3 in 10%treatment group was significantly higher than that of the other three groups（P<0.05）.After feeding fermented tangerine peel for 42 days,the content of serum C4 in fermented tangerine peel treatment group was significantly higher than that of control group and Vit C treatment group（P<0.01）.After feeding for 28 days or 42 days,the content of TNF-αin the 5%and 10%treatment groups was significantly lower than that in the control group（P<0.05）,and the content of serum IL-4 showed an upward trend,which was higher than that in the control group（P<0.01）.The content of serum IL-10 in the 10%treatment group was also significantly higher than that in the other experimental groups（P<0.01）.（4）In terms of antioxidant properties,Vit C treatment group,5%and 10%treatment groups could significantly reduce the content of MDA（P<0.01）and significantly increase the content of T-AOC（P<0.01）after feeding fermented tangerine peel for 28 d and 42 d.At feeding with fermented tangerine peel for 14 days,these three treatment groups could significantly increase the total content of SOD（P<0.01）.（5）As far as anti-stress ability is concerned,the contents of serum CORT and ACTH in Vit C treatment group and 10%treatment group reduced,and there was a significant difference with the other groups（P<0.05）.Therefore,the growth performance,immune performance and antioxidant performance of Sanhuang chickens could be improved by adding 5%or 10%fermented tangerine peel to the basal diet,and their anti-stress ability could also be enhanced by adding 10%fermented tangerine peel.2.Effects of fermented passion fruit peel on flavor of Sanhuang chickenThree different ratios of strains（Bacillus subtilis:Candida utilis:Lactobacillus plantarum=1:1:1,1:1:2 or 2:1:3）were used to ferment passion fruit peel at35°C for 3 days.The appropriate addition ratio would be screened based on detecting the type and content of volatile substances and the key aroma;The suitable fermentation time was explored according to the content of key aroma substances after being fermented for 0 to 7 days with the appropriate addition ratio to optimize the fermentation process of passion fruit peel.Then,90-day-old Sanhuang chickens were selected and fed a basal diet supplemented with 0%（control group）,2.5%、5%and10%fermented passion fruit peel for 30 days,respectively.The chicken samples were collected to determine the volatile substances and for taste test to explore the effects of fermented passion fruit peel on chicken flavor.（1）When the ratio of Bacillus subtilis:Candida utilis:Lactobacillus plantarum is1:1:1 or 1:1:2,a variety of new esters with fruity and floral aroma can be founded.And there are 8 important aroma compounds in the treatment group at the ratio of 1:1:2,the overall aroma is good,which not only retained the important flavor of the original peel,but also gave other floral and fruity aroma.Therefore,the overall aroma of passion fruit peel fermented by strains at the ratio of 1:1:2 was good,and the important flavor compounds mainly include floral aroma,fruit aroma and wine aroma,their relative contents gradually increased with the prolonged fermentation time,On the 5^th day of fermentation,the relative content of n-hexanol was 14.08%,and the content of 3-hexen-1-ol was 11.09%.（2）The volatile compounds in 2.5%and 5%treatment groups were mainly alcohols and aldehydes.The content of hexanal in the 5%treatment group was about 32.87%,and the contents of n-heptanol and n-hexanol were 0.43%and0.95%,respectively,which were higher than those in the 2.5%treatment group and the control group.The new generated substances in the 10%treatment group were mainly acids,alkanes and aldehydes,of which the relative content of pimelic acid was 11.81%,the relative content of alkanes was 30.08%,and the relative content of aldehydes was14.69%.Hexanol was the main aroma substance in the peel of fermented passion fruit,which was detected in both 2.5%and 5%treatment groups,and its content in 5%treatment group was higher than that of 2.5%treatment group.Therefore,supplement5%fermented passion fruit peel to the diet can improve the flavor of chicken.Conclusions:Bacillus subtilis:Candida utilis:Lactobacillus plantarum at the ratio of 1:1:2 and the inoculation amount of 10%were suggested to ferment tangerine peel at 35°C and for 4 days to prepare into fermented feed,adding 5%or 10%fermented tangerine peel into the basal diet of Sanhuang chicken can improve its growth performance and disease resistance;The same ratio of strains and inoculation amount are used to ferment the passionfruit peel at 35℃for 5 days,adding 5%fermented passionfruit peel to the basal diet of Sanhuang chicken has the efficacy of improving the flavor of chicken.