Ropey Bread

ROPEY BREAD, a microbial mucous degeneration of bread caused by the potato bacillus (see below). This disease manifests in that the bread emits an unpleasant odor, its crust loses elasticity, and the crumb first in individual areas, and then throughout its entire thickness, becomes mucous; when broken, the bread stretches into long, mucous threads. The disease is usually discovered no earlier than two days after the bread is baked. The potato bacillus (see below), which is the cause of this bread disease, is in the vast majority of cases introduced into the dough along with contaminated flour; in other, rarer cases, it can enter the dough from bakery utensils that have been soiled and contaminated by it. For the development of the ropey bread disease, the following conditions are necessary: sufficient moisture in the bread, a storage duration of at least 2 days, and a sufficiently high temperature during storage (not lower than 15°). Therefore, the ropey bread disease most often develops in the warm summer months and affects primarily large loaves of bread in cases where the latter are stored for a long time in stuffy, unventilated rooms. Conditions that prevent the development of the disease are: low temperature during storage, high acidity of the bread, and rapid consumption of the baked goods. The degree of contamination of the initial flour with the potato bacillus is of great importance. Bread made from higher grades of flour is less susceptible to the ropey bread disease, since the development of this disease is quite closely related to the amount of bran in the flour, which are the primary carriers of the infection. The reason for the easy spread of the infection is the extreme resistance of the spores of the potato bacillus, which freely withstand the temperature inside the loaf (98-99°) even during the longest baking process. During long storage, diseased bread can serve as a source of infection for healthy bread. Since the potato bacillus is not pathogenic to humans, the consumption of contaminated bread before the development of symptoms of spoilage (foul odor, etc.) is considered safe and permissible. Bread may prove harmful and therefore unfit for food only after the development of the ropey bread disease due to the accumulation of the metabolic products of the potato bacillus, among which there may be poisonous protein decomposition products. When eating such bread, mild gastrointestinal disorders (nausea, vomiting, diarrhea) may develop. Ordinary laxatives can be considered sufficient to eliminate the symptoms of the illness. To resolve the question of the suitability of contaminated flour for baking purposes, the most rational method should be considered trial baking, performed under different conditions (reduced and increased humidity and acidity), since the goal of the study is not so much the detection of the potato bacillus as the clarification of the possibility of using the flour under certain conditions. Sometimes the potato bacillus causes such a massive disease of bread that the question arises of special measures to combat this kind of hazard. In addition to general sanitary measures (observing cleanliness in bakeries, periodic whitewashing of them, etc.), a whole series of measures based on the special properties of the potato bacillus should be undertaken here; these measures briefly boil down to the following. 1. The use of milling from pre-washed grain, as well as the production of high-grade flour, can contribute to reducing the degree of flour contamination. 2. The high sensitivity of the potato bacillus to cold makes it possible to use contaminated flour in winter without much risk of the appearance of the ropey bread disease in the bread. 3. The rapid production of rusks from bread protects against the manifestation of the ropey bread disease. 4. A very great service is provided by making dough on sour whey or adding 0.25% lactic acid or 0.1% acetic acid to the dough. 5. Since small units of bread bake better, are consumed as food more quickly, and are usually less moist, then, all other things being equal, it is more profitable to bake bread in small forms. 6. Contaminated utensils in bakeries must be disinfected with weak solutions of sulfuric or acetic acids, followed by washing with boiling water. Walls and floors must be thoroughly cleaned and washed with hot lye.

7. Warehouses for storing bread must be ventilated and, if possible, have a temperature no higher than 15-18°. 8. Bread in warehouses should be stored for the shortest possible time (no more than 1 day). 9. Disinfection of flour storage facilities (granaries, bins, bakeries), as experience has shown, is extremely difficult to carry out and does not lead to the goal. It is possible to use disinfection of containers (sacks) in steam apparatuses in some cases. The Scientific Medical Council of the People's Commissariat of Health of the RSFSR published a special resolution dated October 26, 1925, outlining in brief all the main measures to combat the ropey bread disease.

Potato bacillus, B. mesentericus, is the name of a fairly extensive group of spore-bearing bacilli, which are extremely widespread and found in soil, on potato tubers, in milk, and in flour (Figs. 1 and 2). One of the species of this group was first described by Koch (R. Koch; 1881), who noticed wet, viscous colonies appearing on the edge of a culture. Flugge and other authors described several types of the potato bacillus

under the names: B. mesentericus vulgatus, B. mes. fuscus, B. mes. hordermis, B. multipediculus, B. mes. ruber, B. panis viscosus, B. mes. niger.

The classification given above was based mainly on the appearance and properties of the colonies. According to morphological properties, the potato bacillus is close to the hay bacillus; according to growth conditions, it is classified as an aerobe, and in other cases, it can be a facultative anaerobe. All species of B. mesentericus (except B. multipediculus) are motile, grow well on nutrient media, and liquefy gelatin. Many of the varieties form pigment, a sign that can be used with great caution when classifying these microbes (Dmitrievskaya). Optimal growth conditions are 22°; for B. mes. vulgatus—from 22° to 30°; B. mes. ruber grows best at 45°. Potato bacilli stain satisfactorily with aniline dyes; they are Gram-positive. Among the biochemical properties of these microorganisms, one should note the energetic slime formation, which results from so-called "dextran fermentation," which produces a complex mucous substance—dextran or viscose. The wide distribution of the potato bacillus in nature is due to the very high resistance of its spores. Globig, studying bacilli found in the soil, found one species—the red potato bacillus, the spores of which turned out to be more resistant than the spores of anthrax, namely: in flowing steam at 100°, these spores died only after 5 1/2–6 hours; in steam under pressure at 109–113°, they remained alive after 45 minutes, at 113–116° they died in 25 minutes, at 122–123° in 10 minutes, and at 130° they died instantly.

The potato bacillus is not classified as a pathogenic microorganism and does not, by itself, cause disease in humans.