贮藏期间不同品种(系)青皮核桃的品质变化

Quality changes of different varieties of green walnut fruit during storage

【目的】研究不同品种(系)青皮核桃在贮藏期间的品质变化规律及差异,筛选贮藏期较长的核桃品种,为延长鲜食核桃供应期提供理论参考。【方法】以甘肃省成县主栽核桃品种(系)‘强特勒’、B0803-5、‘陇南755’和‘清香’为试验材料,用厚度为40µm聚乙烯袋(PE 40)包装核桃青果,于温度(0±1)℃、相对湿度70%~80%的条件下贮藏,定期对其品质指标进行观察测定。【结果】在贮藏过程中,所有供试核桃青皮均出现褐变现象,且随着贮藏时长的增加,褐变程度不断加重。其中,‘强特勒’开始褐变的时间较晚,但后期褐变最为严重,其次为B0803-5,‘陇南755’和‘清香’褐变程度较轻。贮藏前45 d,核桃感官品质较稳定,随着贮藏时长增加,所有感官品质均急剧下降。其中,种皮色泽和剥皮难度分数下降最快,其次为种壳色泽,种仁风味分数下降速度最慢。贮藏结束时,按照感官品质综合评分由高到低排序,各品种(系)依次为‘清香’、B0803-5、‘陇南755’、‘强特勒’。随着贮藏时长的增加,所有供试核桃核仁水分和粗脂肪含量均下降,‘强特勒’水分含量变化较小,但粗脂肪含量变化最大,B0803-5水分和粗脂肪含量变化均较小。随着贮藏时长的增加,所有供试核桃核仁蛋白质含量先升后降,变化最大的为‘强特勒’,最小的为‘清香’。随着贮藏时长的增加,所有供试核桃核仁可溶性糖含量均下降,‘陇南755’下降幅度最大,‘清香’下降幅度最小。所有供试核桃在贮藏期内核仁油脂较稳定,均具有较好的品质,‘强特勒’的油脂氧化程度和膜脂过氧化程度最高,‘陇南755’的最低。【结论】贮藏初期(30 d)核桃青皮褐化程度较轻,且品种(系)间变化不大,贮藏45 d后褐化程度加重,品种(系)间差异显著;贮藏期间所有供试核桃核仁含水量变化较小,贮藏结束时水分含量均大于17%,具有鲜水果的特征;所有供试核桃核仁油脂较稳定,在整个贮藏期内均具有较好的品质。‘清香’和‘陇南755’贮藏效果最佳,可贮藏90 d;其次为B3803-5,可贮藏75 d;‘强特勒’贮藏效果较差。

【Objective】The purpose of this research was to discuss the quality changes of different green walnut fruits during storage and to select the walnut varieties with long storable properties,which provided a theoretical reference for prolonging the supply period of fresh walnuts.【Method】The Juglans regia cultivars of‘Chandler’,B0803-5,‘Longnan 755’and‘Qingxiang’from Chengxian of Gansu province were used as experimental materials.The green walnut were packaged by 40μm polyethylene bags(PE40)with stored temperature of(0±1)℃and relative humidity of 70%-80%.The quality indexes were observed regularly.【Result】During the storage,browning occurred in all walnut epicarps,and the browning degree increased with the storage time.Among them,‘Chandler’started browning later,but the late browning was the most serious,followed by B0803-5,‘Longnan 755’and‘Qingxiang’was relatively lighter.In the early 45 storage days,the sensory quality of walnut was stable.However,all sensory qualities decreased sharply with increasing of storage time.Among them,endotesta color and peeling difficulty fraction decreased the fastest,followed by seed shell color,and kernel flavor fraction decreased the slowest.After 90-day storage,according to comprehensive score of sensory quality,the decreased order of the tested varieties was‘Qingxiang’,B0803-5,‘Longnan 755’and‘Chandler’.Along with the increase of storage time,the water content and crude fat content of all walnut kernels decreased,the water content of‘Chandler’changed little,but the crude fat content changed the most,B0803-5 changed little;the protein content of walnut kernel in all the tested samples first increased and then decreased,with the biggest change being‘Chandler’and the smallest being‘Qingxiang’;the soluble sugar content of all walnut kernels decreased,while that of‘Longnan 755’decreased the most and that of‘Qingxiang’the least.All the tested walnut kernel oils were stable and had good quality during the storage period.The degree of lipid oxidation and membrane lipid peroxidation of‘Chandler’was the highest,and that of‘Longnan 755’was the lowest.【Conclusion】At the beginning of storage(30 days),the browning degree of walnut green skin was light,and there was no significant change among varieties.After 45-day storage,the browning degree was more serious,and the differences among varieties were significant.The water content of all tested walnut kernels changed little during storage,which was more than 17%after storage,which satisfied the characteristics of fresh fruit.All walnut kernel oil was stable,and had good quality in the whole storage period.‘Qingxiang’and‘Longnan 755’had the best storage performance,which could be stored for 90 days,followed by B3803-5,which could be stored for 75 days,and‘Chandler’had poor storage performance.