Study On Processing Suitability Of Citrus Whole Fruit And Storage Stability Of Whole Fruit Juice Products

Citrus is one of the four major fruits in the world,the fruit is nutritious and healthy,and is deeply loved by people.With the improvement of living standards,people’s demand for citrus processed products is increasing day by day.At present,the processing produces a large number of by-products,which are often not properly used.Citrus whole fruit juice can realize the utilization of whole citrus,fully retain the nutrients and bioactive components of citrus,and will help develop resource-saving and environment-friendly industries.This study was conducted through selection of whole fruit juice varieties,processing safety and storage stability analysis to provide theoretical basis for the development of citrus whole juice products.The main findings are as follows:(1)To study the quality characteristics of whole fruit juice of different citrus varieties in Hunan province,qualities of 12 citrus varieties were determined to select suitable varieties for processing juice.Comprehensive evaluation was investigated by principal component analysis.The results showed that the difference of seed number,a* value,titratable acid,naringin,rutin naringin,and orange flavone content of different varieties of citrus whole fruits were larger,while the difference of juice yield,L* value,and soluble solids was small.Decanal,linalool,α-terpineol,γ-terpinene,etc are characteristic volatile organic compounds which play an important role in regulating the overall aroma of whole citrus juice.The important principal components were extracted by principal component analysis,combined with quality analysis and selected citrus varieties suitable for whole fruit juice.(2)To explore the processing safety of navel orange whole fruit by different cleaning methods combined with grinding oil treatment.Five cleaning methods could remove pesticide residues with varying degrees in whole navel orange samples.The processing factors of each pesticide varied in the range of 0.298 9-0.899 6.Ozone water cleaning had a better removal effect on pesticides.After five cleaning methods combined with grinding oil treatment,pesticide residues on whole navel orange samples were significantly removed.The processing factors were 0.000 8-0.232 8,only 0.10%-27.19% of the whole navel orange with no grinding oil.Ozone water combined with grinding oil was proved to be the most effective pesticide removal method.(3)To study the effects of different storage temperatures on the quality of whole navel orange juice.Three temperature gradients,4 ℃,normal temperature and 37 ℃,were used to store the whole navel orange juice for 7 week.During the storage period,the a* value of the color index was most affected by the storage time and temperature.ΔE value at 37 ℃ was higher than that at 4 ℃ and normal temperature storage;the change trend of total soluble solids and titratable acid was relatively gentle;the retention rates of soluble protein were 83.33%,70.00% and 60.00%,respectively;the retention rates of reducing sugar were 80.70%,72.59% and 76.04%,respectively.The production of 5-HMF at normal temperature and 37 ℃ was significantly higher than that at 4 ℃.Ascorbic acid content decreased with storage time.A total of 45 volatile organic compounds were identified,The contents of limonene,α-pinene and laurene,which contributed significantly to the aroma of navel orange,decreased during storage,while the contents of α-and β-terpineol furfural and p-vinyl guaiacol increased.Overall,storage at 4 ℃ is more conducive to maintain the quality of whole juice.