Production process of flavor old vinegar capable of increasing content of non-volatile acid and amino acid nitrogen

The invention discloses a production process of flavor old vinegar capable of improving the content of non-volatile acid and amino acid nitrogen. The production process mainly comprises the following steps: preparing aspergillus flavus koji, specially preparing hanging medicine koji, preparing fermentation heads, spreading rice to prepare fermented grains, putting into a cylinder in a layered manner, pressing the fermented grains and sealing the cylinder, solarizing three-side solid vinegar fermented grains for fermentation, performing high-temperature post-fermentation, spraying vinegar, and ageing to prepare a finished product of the flavor old vinegar. The invention also provides a compound fruity old vinegar product prepared by using the production process, which is prepared by compounding the prepared flavored old vinegar, Chinese wolfberry juice, grape juice and apple juice in proportion, adding fruity essence and a flavoring agent, sterilizing and packaging to obtain the compound fruity old vinegar fin