Development of fermented sauce-based salads : assessment of safety and stability

Sauce-based delicatessen salads, composed of solid ingredients, such as potatoes, vegetables, fish, meat and an oil-in-water emulsion containing acidulants (acetic and lactic acids) and chemical preservatives (sorbic and benzoic acids) can be subject to microbial and chemical changes and physical deterioration. In this thesis a new method of salad preparation is presented which meets consumer demands for salads without chemical preservatives and with a less sour taste and by which the major microbiological and chemical problems of the present-day salads can be controlled. Conditions for operation and the microbiological and chemical aspects that are relevant for the process have been investigated. It is shown that preparation of salads by the new process, i.e. fermentation in their package with lactic acid bacteria at higher temperatures (≥42°C) in a short time (≤8 hours), followed by cooling to below 7°C, is feasible. Salads produced according to this procedure have a mildly sour taste and are microbially stable for 5-6 weeks at 7°C, i.e. yeasts and other spoilage organisms are inhibited, provided that measures are taken to assure low initial contamination with these microorganisms. Moreover, fermented salads, subjected to light exposure, are protected for lipid photo-oxidation. This protection is apparently due to the oxygen scavenging and reducing effects of the fermentation. The salads could be regarded as safe, as growth of pathogenic microorganisms and production of biogenic amines are inhibited.