Evaluation And Application Of Citrus Flavonoids As Sweeteners And Bitterness Inhibitors

The fruits and pericarps of citrus in rutaceae are rich in flavonoids with significant biological activities.In recent years,it has been found that citrus flavonoids and their derivatives(in this paper,they are called citrus flavonoids)have many important pharmacological activities,such as scavenging free radicals,antioxidation,anti-tumor and anti-inflammatory,so they have been concerned by many researchers.Some citrus flavonoids can be used as sweeteners or bitterness inhibitors.For example,the neohesperidin dihydrochalcone(NHDC),a derivative of the neohesperidin hydrogenated from the acid orange,has the characteristics of high sweetness,low calorific value,safety and non-toxic.It has been used in food,medicine and feed as sweetener,fragrance enhancer and flavor corrector in Europe.Neodiosmin is a flavonoid glycoside separated from the acid orange,which can inhibit the bitterness of naringin and limonoids in fruit processing and do not affect their activity.Therefore,it is of great significance to study the sweet taste evaluation and bitter inhibition of citrus flavonoids for promoting the healthy development of functional food and pharmaceutical auxiliary materials industry.In this paper,the sweetness characteristics of dihydrochalcone sweeteners of citrus flavonoids were evaluated by sensory evaluation and electronic tongue method respectively,and the bitterness inhibition effects of several citrus flavonoids were investigated.The specific work is as follows.1.The taste characteristics and sweetness intensity of NHDC and naringin dihydrochalcone(NDHC)sweeteners were studied by sensory evaluation and electronic tongue method,and compared with 7 kinds of sweeteners such as sucralose and saccharin sodium.The results of sensory evaluation showed that NHDC and sucralose had pure sweetness,and the taste was close to that of sucrose.NDHC is similar to liquorice in sweetness and lasts shorter than NHDC.With 50 g/L sucrose solution as reference,NHDC was about 1000 times sweeter than sucrose,while NDHC was about 100 times sweeter than sucrose.The results of electronic tongue evaluation showed that GL1 could effectively detect the sweet information of six sweeteners including NHDC and NDHC.Electronic tongue technology combined with principal component analysis and cluster analysis can effectively classify sweeteners,among which NHDC and sucrose are in the same group,indicating that the overall taste characteristics of NHDC are similar to those of sucrose;NDHC is the closest to NHDC.The quantitative prediction model between the measurement value of electronic tongue and sensory evaluation results of five sweeteners with positive sweetness response was established.The statistical results show that the established sweetness prediction model has high accuracy and good prediction effect.2.The inhibitory effects of 12 citrus flavonoids on the bitter taste of naringin(0.48 g/L),quinine hydrochloride(0.1 g/L)and stevioside(2.5 g/L)were evaluated by the method of quantity estimation and electronic tongue,respectively.The results of sensory evaluation showed that when the concentration was 40 mg/L,the inhibition rate of NHDC was 54% for naringin,NHDC > neodiosmin > naringenin,and 43% for quinine hydrochloride,NHDC > neodiosmin > hesperidin dihydrochalcone-7-o-glucoside(HDC-7-G),and 42% for stevioside.NHDC and neodiosmin have a good effect on inhibiting the bitterness of three target bitterness test products.The results of electronic tongue evaluation showed that the addition of neodiosmin,NHDC or HDC-7-G could reduce the bitterness response value of quinine hydrochloride,which showed that the results of electronic tongue method were basically consistent with those of sensory evaluation.3.Through the analysis of the correlation between the molecular structure of citrus flavonoids and their corresponding bitter inhibition effect,it was found that the 7-linked glycosyl group in the A-ring of citrus flavonoids skeleton had an important effect on the bitter inhibition effect,and the 7-linked neohesperidosyloxy had the best bitter inhibition effect,followed by glucosyl.The study on the structure-activity relationship between these compounds and their bitter inhibition effect has not been reported.4.The ternary compound bitter inhibiting composition of citrus flavonoids and β-cyclodextrin inclusion compound of neodiosmin were prepared,and their inhibitory effects on the above three bitter samples were investigated.The results showed that when the concentration of NHDC,neodiosmin and naringenin(I)was 30,20 and 40 mg/L,the inhibition rate of naringin solution was 68 %,and the bitter intensity of naringin solution could be reduced from bitter to no bitter.When the concentrations of NHDC,neodiosmin and HDC-7-G were 20,40 and 50 mg/L respectively,the inhibition rate of bitter taste of stevioside was 75%,and the stevioside solution could be reduced from bitter to no bitter.The inhibitory effect of ternary compound method on quinine hydrochloride was similar to that of 40 mg/L NHDC solution.Neodiosmin/β-cyclodextrin inclusion complex(II),n(cyclodextrin):n(neodiosmin)= 10:1,the water solubility at room temperature is better than neodiosmin,which can reduce the bitter intensity of naringin solution from bitter to slightly bitter.Compound(I)and inclusion compound(II)were applied to orange wine respectively.The results showed that both of them could reduce the bitterness of the wine.Compound(I)had a better effect on inhibiting the bitterness of the orange wine.NHDC also increased the sweetness of the wine,and the overall flavor of the wine was better.In conclusion,this paper provides an effective way and scientific reference for the quality evaluation of two kinds of dihydrochalcone sweeteners and commonly used artificial sweeteners and the research and development of product formula,which can be used to screen out the compounds and compounds of citrus flavonoids with obvious bitterness inhibition effect for three kinds of bitter test products.