One of the most important variables in pome and stone fruit sanitation is the temperature relationship between the fruit and the wash water. Apples, pears, peaches, nectarines, and similar commodities can experience water infiltration through stem scars, lenticels, punctures, and other surface defects when fruit temperature exceeds wash water temperature. Infiltration can allow microorganisms present in wash water to move beyond the fruit surface, increasing the risk of internal contamination.
To minimize this risk, packing facilities typically maintain wash and dump tank water above fruit pulp temperature. Many operations target a differential of approximately 5–10°F (3–6°C), although the appropriate temperature differential varies by commodity, facility SOP, and customer requirements.
Temperature management also influences sanitizer performance:
- Chlorine efficacy decreases as water temperature drops.
- Cold water may require increased sanitizer concentration or extended contact time to achieve the same antimicrobial performance.
- Temperature-controlled dump tanks often require dedicated sanitizer dosing on both make-up water and recirculated wash water to maintain consistent residual levels throughout the process.
Water-powered proportional dosing helps maintain accurate sanitizer concentrations despite changing flow rates, seasonal water temperatures, and varying production conditions. While dosing systems do not control water temperature directly, they help ensure sanitizer concentration remains within the target operating range established by the facility's food safety program.
