Yeasts Occurring on Dates.
نویسندگان
چکیده
Dates sometimes undergo a yeast fermentation even though they appear to be sufficiently low in moisture and high in sugar content to inhibit the development of most spoilage organisms. In the packing of dates the procedures followed, as outlined by Sievers and Barger (1930) do not involve the use of preservatives or of sufficient heat to prevent yeast growth. In fact, yeast spoilage has been observed at all stages of handling from harvesting to packing and distribution. Fermentation and yeast growth on dates are usually slow and frequently overlooked although undesirable odors are commonly present. Occasionally, however, fermentation is accompanied by the formation of subcutaneous gas pockets or rupturing of the skin. Several investigators have given consideration to the morphology and taxonomy of yeasts obtained from dates, although in most instances relatively few organisms were studied. Rodio (1924) observed the formation of a white crust in the wrinkles of the pericarp and particularly in the cracks of the epidermis. Yeasts isolated from this white material were described as Zygosaccharomyces cavarae. Later Beauverie (1929) also isolated this organism as well as Z. cavarae var. beauverie from the skin scrapings of Tunisian dates. Verona and Valleggi (1933) isolated and described Hansenula fermentans characterized by the fermentation of both maltose and lactose, but unfortunately this unusual yeast was lost. Esau and Cruess (1933) obtained two distinct groups of yeast from fermented California dates; one termed Saccharomyces because of the strong alcohol-forming powers, and a second termed "torula yeast" because of the moderate production of alcohol.' Melliger (1931) studied yeasts isolated from two distinct types of Egyptian dates which were char-
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ورودعنوان ژورنال:
- Journal of bacteriology
دوره 43 6 شماره
صفحات -
تاریخ انتشار 1942