Hurdle Technology Applied to Lucuma (Pouteria Lucuma) Fruit Pulp: Microbial Aspects

Hurdle technology was applied to lucuma fruit pulp by slight reduction of water activity (a_W) and pH. The original a_W (0.97) and pH (5.2) of the pulp were reduced to 0.92 and 0.90, and to 4.7 and 4.4, respectively. Growth of spoilage microorganisms (total viable count (TVC), yeasts, molds, coliforms, and Escherichia coli) was monitored during the 90-day refrigerated storage. The combined reduction of a_W and pH of lucuma pulp kept TVC under control and caused a reduction of yeast population. However, individual reduction of a_W or pH was not as effective on TVC and yeast. On the other hand, molds and coliforms were undetected after 60 and 90 days of storage in all lucuma samples, respectively. In conclusion, a microbiologically stable lucuma pulp, under refrigerated conditions, could be obtained by reducing its a_W to at least 0.92, and simultaneously reducing its pH to at least 4.7.