Control of Byssochlamys and Related Heat-resistant Fungi in Grape Products

Abstract

Heat-resistant strains of Byssochlamys fulva, B. nivea, and other heat-resistant fungi were isolated from vineyard soil, grapes, grape-processing lines, and waste pomace. They are known to remain in grape juice occasionally and to grow in grape juice products. Ascospores of these fungi have a D value (decimal reduction time) of about 10 min at 190 F (88 C), but in the presence of 90 Bliters of SO2 per liter (normally added to the juice) the D value was cut in half. Filtration through a commercial diatomaceous filter aid (also a common processing step) entrapped all but about 0.001% of experimentally added spores. Thus, heat in the presence of SO2 and filtration together can reduce the population of these spores by several orders of magnitude. Growth was also prevented by benzoate or sorbate in low concentrations. Oxygen must be reduced to extremely low levels before lack of oxygen limits growth.

Heat resistance of Byssochlamys nivea, Byssochlamys fulva and Neosartorya fischeri isolated from canned tomato paste

“…Bayne and Michener (1979) studied heat resistance of B. fulva in a defined medium consisting of 16Њ Brix glucose and 0.033M tartaric acid and calculated 3 log 10 inactivation times of 1.2 to 46 min at 90ЊC. King et al (1969) reported a B. fulva heat resistance of D 87.8ЊC of 11.3 min in grape juice. Some strains of B. fulva have reported D-values at 90ЊC of 1 to 12 min (Scott and Bernard, 1987).…”

The Destruction of Byssochlamys fulva asci by Low Concentrations of Gaseous Methyl Bromide and by Aqueous Solutions of Chlorine, an Iodophor and Peracetic Acid

“…Preparation of asci Byssochhmys fulva NRRL 3493 asci were produced by the method of King et al (1969) except that the mould was grown in 1 1 fermentation flasks instead of in flat sided bottles. All experiments described were done with intact asci.…”

“…Because of the rarity of B. fulva ascospores in foods, a minimal heat treatment is suggested for acidic foods (Maunder, 1969). The heat resistance of the ascospore is sufficiently high (King, Michener & Ito, 1969) for heavier than normal contaminations to cause food spoilage problems.…”

Physiological and Metabolic Attributes of Microbial Groups Associated with Foods

“…It used to be thought that no development of moulds or bacteria of the genus Bacillus was possible in, for instance, canned or other packaged foods because of the existing vacuum, usually 45-25 cm Hg residual pressure, corresponding with a PO, of 90-50 mm. But fungi which actively spoil fruits, fruit juices or agricultural staples have been shown to develop in a PO, of c. 50-10 mm (Tabak & Cooke, 1968; Sanders, Davis & Diener, 1968;King, Michener & Ito, 1969) arid a Xeromyces sp.…”