Extraction And Modification Of Pectin And Naringin From Pomelo Drop And Their Application In Yogurt Processing

The development of grapefruit fruit produces a large number of physiological fruit drop and artificial fruit thinning,compared with mature fruit and peel,grapefruit fruit drop is richer in bioactive components such as gum and flavonoids.At present,the exploitation of grapefruit fallen fruits has not been paid attention to,and the full exploitation of these immature waste fruits will greatly improve the economic added value of grapefruit planting and processing industry.In this paper,the pectin and flavonoids(naringin mainly)were extracted continuously from the fallen fruits of grapefruit,and the extracts were modified and applied to the new yogurt processing.The main research of this paper is as follows:1.The extraction process of pectin and naringin was studied.The continuous extraction process of pectin and then naringin and the continuous extraction process of naringin and then pectin were investigated.The best extraction process of pectin and naringin was obtained by single-factor test and response surface optimization:firstly,70% ethanol was used to extract naringin at 70 ℃,extraction time 110 min,and liquid to material ratio 15:1(v/w),and then the filter residue was used to extract pectin with acetic acid at p H 1.50,extraction temperature 80 ℃,extraction time 160 min,and liquid to material ratio 40:1(v/w).The extraction temperature was 80 ℃,extraction time was 160 min,liquid to material ratio was 40:1(v/w),the extraction rate of naringin was 42.77% and the yield of pectin was 14.32%;the pectin extracted under this route was low ester pectin.2.Naringin was used as raw material to synthesize novel sweeteners.The new naringin was synthesized by hydrolysis of naringin to open the ring,aldehyde-ketone condensation and hydrogenation of naringin dihydrochalcone.The products of each reaction step were analyzed qualitatively and quantitatively by HPLC;and the condensation reaction conditions were optimized by orthogonal tests to obtain the optimal process parameters: anhydrous ethanol:PN=10:1(v/m)with pyrrolidine and acetic acid as the catalytic system,reaction temperature of 80 ℃,reaction time of 12 h,n(PN):n(isovanillin):n(catalyst)=1:1:1.25,and neohesperidin The conversion rate of neohesperidin reached 90.6%;the total conversion rate of naringin synthesis of neohesperidin dihydrochalcone reached 67.5%.3.Application to yogurt processing study.The pre obtained grapefruit pectin was used as stabilizer and the synthesized neohesperidin dihydrochalcone was used as sweetener to study the application of both in yogurt processing.Through the determination of relevant physicochemical indexes and sensory evaluation,it was determined that the addition of pectin and neohesperidin dihydrochalcone at 0.10%and 0.15‰,respectively,resulted in better water-holding capacity,total number of lactic acid bacteria and sensory evaluation than the yogurt without the addition of pectin and neohesperidin dihydrochalcone.