agar and calcium-propionate

The major objective of this study was to assess the antifungal activities of commercially available 'clean label' fermentates and their potential to replace the preservative function of sorbate and propionate in cake. This study was performed in two parts. In the first part of the study the inhibitory activities of selected fermentates - FA, FB, FC and FD - towards Aspergillus tritici and Aspergillus amstelodami were assessed as a function of pH (5.0-6.5) on malt extract agar (MEA). In the second part of the study, challenge, shelf-life and sensorial tests were used to determine the suitability of these fermentates to replace potassium sorbate and calcium propionate in quarter pound cake. All the fermentates evaluated in this study all had significant (p<0.05) inhibitory activities towards A. tritici and A. amstelodami within the recommended dosage range for application in bakery products. In all cases, the inhibitory activity of the fermentates increased with a decrease in the pH and an increase in concentration. FC was generally the most inhibitory whilst FD was the least inhibitory. Significant (p<0.05) synergistic interactions were determined to occur between the effects of pH and concentration for all fermentates evaluated in this study. The sensorial tests with FC showed that cakes produced with ≤1% FC (on basis of the batter) did not differ significantly (p>0.05) in flavour from the reference cake (0.5% calcium propionate and 0.54% potassium sorbate). However, the challenge and shelf-life tests showed that cakes produced with ≤1% FC were not as microbiologically shelf-stable as the reference cake, especially when sliced. Therefore, it can be concluded that whilst fermentates have appreciable antifungal effects, their use could potentially result in reduced shelf-stabilities. Robust challenge and shelf-life tests would be recommended before the marketing of cakes were propionate and/or sorbate has been replaced to ensure accurate shelf-lives are stated.

Topics: Agar; Aspergillus; Bread; Fermentation; Food Industry; Food Microbiology; Food Preservation; Food Preservatives; Fungicides, Industrial; Hydrogen-Ion Concentration; Propionates; Sorbic Acid

Some species of molds are capable of degrading sorbic acid to produce 1,3-pentadiene, a volatile compound with an unpleasant hydrocarbon-like odor. The effectiveness of reduced concentrations of sorbate, in combination with other antimycotics, to control the growth of these molds has not been described. We did a study to evaluate potassium sorbate, sodium benzoate, calcium propionate, disodium ethylenediaminetetraacetic acid (EDTA), and natamycin, alone and in combination, for their effectiveness in preventing the growth of five molds isolated from Parmesan cheese and a lemon-flavored drink subjectively judged to contain 1,3-pentadiene. Growth of Penicillium brevicompactum, Penicillium roqueforti, Paecilomyces variotii, Aspergillus niger, and Cephaloascus fragrans on model agar media containing Parmesan cheese (PRM agar) (pH 5.5) and lemon-flavored drink (LD agar) (pH 2.6) supplemented with antimycotics was studied. All molds grew well at 21 degrees C on PRM agar containing potassium sorbate (3500microg/ml), calcium propionate (3000microg/ml), or natamycin (20microg/ml). Combinations of potassium sorbate (250-1000microg/ml), calcium propionate (250-1000microg/ml), and/or natamycin (10-18microg/ml) greatly inhibited or prevented growth of molds on PRM agar, indicating their potential as preservative systems at pH values resulting in large percentages of the acids in dissociated forms. Three of the five molds grew on LD agar containing potassium sorbate or sodium benzoate at a concentration of 200microg/ml. Growth did not occur within 70 days on LD agar containing EDTA (30microg/ml) in combination with potassium sorbate and sodium benzoate at 50 and 175microg/ml, respectively, or 175 and 50microg/ml, respectively. Results of this study show that preservative systems containing a reduced concentration of potassium sorbate, in combination with other antimycotics, particularly natamycin, have potential for controlling the growth of molds thought to be capable of producing 1,3-pentadiene.

Topics: Agar; Alkadienes; Antifungal Agents; Beverages; Cheese; Citrus; Colony Count, Microbial; Dose-Response Relationship, Drug; Edetic Acid; Food Contamination; Food Microbiology; Food Preservatives; Fungi; Hydrogen-Ion Concentration; Natamycin; Odorants; Pentanes; Propionates; Sodium Benzoate; Sorbic Acid; Species Specificity