Abstract:

This study aimed to investigate the multidimensional effects of fruit bag color on apple quality characteristics，clarify the roles of different colored bags in regulating fruit appearance，texture，nutritional composition，flavor，and aroma profiles，and provide theoretical support for optimizing fruit bagging techniques. Using 6-year-old‘Harlikar/Malus hupehensis’trees as test materials，seven bagging treatments were applied：white-green double-layer bags，orange bags，yellow bags，green bags，blue bags，brown-black double-layer bags and brown-red double-layer bags（control）. Fifty-two parameters were measured，including appearance characteristics（single fruit weight，fruit shape index and color），texture Parameters（firmness，elasticity，etc.），nutritional quality（soluble sugars，vitamin C，mineral elements，etc.），and flavor profiles（electronic nose and electronic tongue sensory systems for the analysis of aroma compound types and flavor.）. The comprehensive evaluation incorporated with differential analysisand principal component analysis（PCA）. The results indicated that in terms of appearance，fruit weight under blue bagging was significantly the highest，but the number of fruit dots was higher；The fruit peel brightness under the brown-red double-layer bag and brown-black double-layer bag treatments was significantly higher than other treatments，while the green bag resulted in the most yellow peel. In terms of texture and quality，the green bag treatment showed the highest soluble sugar，VC，and total phenol contents，along with a significant increase in fruit firmness. The blue bags enhanced the content of soluble solids，soluble protein，and solid/acid ratio with the yellow bag significantly boosting mineral elements such as N，K，Ca，and Fe. The blue bag improved flesh elasticity. In terms to flavor ，electronic tongue analysis revealed that the fruit was primarily sweet and umami，with overall weak sourness. The sweet taste response was highest with the blue and yellow bags，while the umami response peaked with the brown-red double-layer bag and was lowest with the orange bag. The brown-black double-layer bag enhanced fruit flavor，and the blue bag reduced astringency. Electronic nose analysis indicated that the fruit aroma mainly derived from sulfides，terpenes，and aromatic components，with the green and yellow bags significantly increasing the contents of these three substances. In conclusion，The green bag treatment achieved the highest comprehensive score，exhibiting optimal performance in aroma，nutrition，and texture，followed by the brown-black double-layer bag.

Key words: apple, fruit bag color, electronic sensory system, quality evaluation, principal component analysis