Hurdle technology was applied to lucuma fruit pulp by slight reduction of water activity (aW) and pH. The original aW (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 aW and pH of lucuma pulp kept TVC under control and caused a reduction of yeast population. However, individual reduction of aW 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 aW to at least 0.92, and simultaneously reducing its pH to at least 4.7.
- minimally processed fruits
- spoilage microorganisms
- synergistic antimicrobial effect