Grafting of Walnut Shell Hemicellulose B with Ferulic Acid and Its Effect on the Volatile Flavor Compounds of Pickles

Ferulic acid hemicellulose B (FCB) was introduced into the pickle fermentation process to alter the flavor compounds of traditional pickles. Hemicellulose B was extracted from walnut shell raw materials and analyzed for protein and nucleic acid content using ultraviolet-visible (UV-Vis) spectroscopy. The grafting of ferulic acid on hemicellulose B in an anaerobic environment and verification of grafting using UV-Vis spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Hemicellulose B and ferulic-acid-grafted hemicellulose B were added to pickles, with unaltered pickles serving as the control, and the aroma compounds generated during fermentation were analyzed using gas chromatography-mass spectrometry (GC-MS). The results showed that the protein and nucleic acid in hemicellulose B were basically removed. UV-Vis and FT-IR spectroscopies confirmed that the grafting reaction produced FCB. Hemicellulose B led to an increase in the derivatization of aroma compounds in pickles during fermentation, whereas the FCB sample generated distinctive aroma components such as sulfur and esters. This study provides a foundation for improving the flavor substances of pickles.