Abstract:

To explore the quality changes of loquat juice during processing, samples were collected at different processing
steps of fresh harvested fruits, color fixation, pulping, enzymatic hydrolysis, filtration and blending for the measurements
of color parameters and soluble solid, titratable acid and total phenolics and total flavonoids contents as well as ABTS+·
scavenging capacity. Meanwhile, volatile compounds were extracted by headspace solid phase microextraction (SPME),
separated and analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that total color difference
exhibited an initial increase, reaching the maximum value after enzymatic hydrolysis, followed by a decrease during loquat
juice processing. Similarly, the contents of soluble solid and titratable acid also decreased first and then increased, with a
significant increase being noted after blending, while the contents of total phenolics and flavonoids and ABTS+· scavenging
capacity tended to decline. The main volatile compounds identified during loquat juice processing were alcohols, aldehydes
and ethers. Principal component analysis (PCA) showed the fresh fruits, the intermediate product after color fixation and the
final product had better nutritional, flavor and aroma quality as well as stronger antioxidant performance, while the steps of
pulping, enzymatic hydrolysis and filtration severely reduced the quality of products to different degrees.

Key words: loquat juice, processing steps, quality, volatile components