新疆野苹果果实生长期的理化性质及褐变程度研究

Evaluation of Physicochemical Properties and Browning Level of Malus sieversii(Ledeb.)M.Roem.during Fruit Growing Period

为明确新疆野苹果种质资源果实生长发育期养分积累情况及果肉褐变程度,以20份新疆野苹果种质资源果实为试材,在整个生长发育期通过测定可溶性糖、可滴定酸、维生素C及果肉色差,探索影响果实品质的主要成分变化趋势及抗氧化性强弱。结果表明:20份野苹果资源的果实在生长发育期可溶性糖和维生素C含量逐渐积累,其中可溶性糖含量阶段性积累趋势明显,在7月10日后进入缓慢积累期,表示果实逐渐进入成熟期,末期含量为7.88%~14.79%,维生素C含量积累至末期为1.78~9.18 mg·hg^(-1),可滴定酸含量先积累后降解,末期为0.18%~2.29%。亮度值L^(*)、红绿值a^(*)、黄蓝值b^(*)均趋近于0,总色差△E逐渐下降,表明随着果实逐渐成熟,果肉的抗氧化能力越强、褐变程度越低,最后对果实抗氧化性相关指标进行综合评价,由强到弱为:‘GB-20’>‘HDM-21’>‘夏’>‘中’>‘红肉1’>‘HDM-12’>‘GB-12’>‘XY-49’>‘XY-58’>‘GB-9’>‘XY-11’>‘XY-75’>‘HDM-11’>‘XY-51’>‘HDM-20’>‘GB-10’>‘克’>‘HDM-39’>‘新定-1’>‘GB-2’。20份新疆野苹果资源中的‘红肉1’‘夏’‘中’‘GB-9’‘GB-10’‘GB-12’‘GB-20’‘XY-11’‘XY-49’‘XY-51’‘XY-58’‘HDM-11’‘HDM-12’‘HDM-21’既是高糖高酸类型,又是高维生素C类型,均可作为功能型资源进行培育,其中‘GB-20’的维生素C含量相较最高且抗氧化性最强,可进一步考虑进行果实深加工。

Malus sieversii(Ledeb.)M.Roem.is a precious germplasm resource mainly distributed in Yili River Valley,known for its exceptional resistance traits.Among the variants of Malus sieversii(Ledeb.)M.Roem,Malus sieversii f.neidzwetzkyana(Dieck)Langenf stands out.Therefore,this experiment mainly studied the nutrient accumulation and flesh browning degree in Malus sieversii(Ledeb.)M.Roem.germplasm resources.Twenty samples of Malus sieversii(Ledeb.)M.Roem.s were used as test materials.During the whole growth and development period,regular fruit harvesting was conducted,and adequate flesh samples were obtained.The soluble solid content was determined using anthracone reagent,the titratable acid content through sodium hydroxide solution titration,and vitamin C content using 2,6-dichlorophenol indiophenol titration.A subset of fruits was transected and exposed to air.With L^(*),a^(*)and b^(*)values measured and recorded every five minutes using chroma meter,followed by a fifteen-minute exposure period.This approach aimed to explore the variation trend of the main components affecting the flavor and the antioxidant capacity of the fruit.The results showed that soluble solid and vitamin C contents of twenty apple germplasm resources were gradually accumulated during the growth and development stage,and the soluble solid content changed significantly at different stages.Steadily accumulated before June 30,rapidly accumulated from June 30 to July 10,and entered the slow accumulation stage after July 10,indicating that the fruit gradually turned the mature stage,and the final content was 7.88%-14.79%.Vitamin C content accumulated to the end stage was 1.78-9.18 mg·hg^(-1).The titratable acid content of eighteen resources showed a trend of accumulation first and then degradation,while the titratable acid content of‘Xinding-1'showed a downward trend during the whole growth period,and the titratable acid content of‘GB-2'was stable and low during the whole growth period,and the acid content of twenty resources at the end was 0.18%-2.29%.The brightness value L~*increased gradually from negative value to zero,red-green value a^(*)decreased gradually from positive value to zero and yellow-blue value b^(*)increased first and then decreased gradually to zero,and the total chromatism△E gradually decreased,indicating that the fruits had stronger antioxidant capacity and lower browning degree as they gradually matured.Finally,comprehensive evaluation of fruit antioxidant related indexes was conducted from strong to weak as follows:‘GB-20'>‘HDM-21'>‘Hongrou 1'>‘Xia'>‘Zhong'>‘GB-12'>‘HDM-12'>‘XY-58'>‘XY-49'>‘XY-75'>‘XY-11'>‘HDM-11'>‘GB-9'>‘XY-51'>‘HDM-39'>‘Xinding-1'>‘GB-10'>‘HDM-20'>‘Ke'>‘GB-2'.Twenty Malus sieversii(Ledeb.)M.Roem.fruits of‘Hongrou1'‘Xia'‘Zhong'‘GB-9'‘GB-10'‘GB-12'‘GB-20'‘XY-11'‘XY-49'‘XY-51'‘XY-58'‘HDM-11'‘HDM-12'‘HDM-21'is both high sugar and acid type and high vitamin C type,which can be cultivated as functional resources,among which‘GB-20'has the highest vitamin C content and the strongest antioxidant,so it can be further considered for further fruit processing.