CHILLING STORAGE OF AN ANTIFUNGAL BIO-CONSERVATIVE STARTER CULTURE FOR PACKED BREAD

FORNAGUERA M.J.; BRU DE LABANDA, E.; FONT DE VALDÉZ G.; TORINO, M.I,

Tucumán. Argentina

Simposio; III Simposio Internacional de Bacterias Lácticas. II Encuentro de la Red BAL Argentina; 2009

III Simposio Internacional de Bacterias Lácticas. II Encuentro de la Red BAL Argentina.

Contamination by fungi is the most common source of microbial spoilage in packed bakery goods. In order to ensure a 15-day shelf-life for packed bread, a bio-conservative lactic starter culture (SL) with antifungal activity was developed to be used with calcium propionate (CP). This work deals with the storage conditions (temperature and time) on the antifungal SL according to industrial parameters, and on some sensory characteristics of bread containing the conserved lactic starter. Bio-conservative culture SL [Lactobacillus plantarum CRL 778 grown (37°C, 16 h) in a low-cost medium containing wheat flour, sucrose, milk and water] was stored at 4 and -20ºC. Samples from 7, 10, and 14 days storage were analyzed [log CFU/ml, pH, titrable acidity (as ºD) and organic acids (HPLC)] and used for baking and bread conservation (days without visible mould growth). Sensorial attributes of breads (acidic and spicy tastes, and acidic smell) were evaluated by a non-trained panel using a qualitative hedonic scale of 5 points. Statistical analysis was carried out respect to a control containing only CP, by using the ANOVA test for mixed models (Infostat 2008p software). The SL maintained its antifungal efficacy on bread shelf life until 14-days storage at both temperatures despite of the differences in cell viability (0.28 log cycles decrease at -20ºC) and acidity (10º D increases at 4ºC). The pH of 3.6 as well as the acetic (ca. 8.0 mM), lactic (233.7 mM) and phenyllactic (ca. 0.27 mM) acids remained unchanged at 4ºC while lactic and phenyllactic acids slightly decreased up to 156.2 and 0.15 mM, respectively, at -20 ºC. The acidic (3.6-3.8) and spicy (3.4-3.5) taste of breads containing SL was considered quite higher than indifferent valuation (punctuation of 3), no significant difference (P>0.05) being observed regarding the temperature and time of SL storage. Similar results were obtained for acidic smell of bread beyond 7-days stored SL. The optimization of antifungal semi-liquid starter SL applied is ongoing in our laboratory. From the findings exposed in this work, it can be concluded that SL may be stored at 4ºC during 14 days without loosing its antifungal activity to reach the desired shelf life in packed bread (15 days). Sensitive attributes slightly changed during chilling conservation.