Vinegar Extract Produced Using Ripe Fruits of Wild Genotype of Citrus depressa Hayata in Okinawa

Shikuwasa (Citrus depressa Hayata) is known as Taiwan tangerine. Various local cultivars are grown, among which the most famous is the ‘Kugani’, which is considered a breeding cultivar. The fruits of this cultivar are used for various purposes (juices, jams, vinegar, etc.) and as a fruit for consumption. The local landrace Ishikunibu is considered wild and is not cultivated on a larger scale because it is dwarf and tastes sour even when harvested in February. This article showed the results of experiments that aimed to show that Ishikunibu fruits are suitable as an addition to the cultivation of these fruits for producing vinegar extract. The results indicate that the vinegar extract of Ishikunibu has properties similar to that of ‘Kugani’. Such vinegar extracts using Ishikunibu have more ascorbic acid (115.2 μg·L⁻¹ vs. 38.9 μg·L⁻¹) and titratable acidity than that of ‘Kugani’. The other quality parameters of such produced vinegar extracts did not differ significantly. The sensory evaluation of vinegar extracts showed no differences in aroma, green smell, and general flavor but vinegar extract of Ishikunibu tasted less bitter. Therefore, Ishikunibu, the wild genotype of shikuwasa, is deemed useful in producing vinegar extracts.