A Liquid Chill System for Rapid Cooling of Meats

An experimental hydrochiller system (HCS) using a recirculated propylene glycol solution was designed and constructed. This system provided more rapid chilling of meats than conventional air chilling (CAC). The unit was tested using beef variety meats (VM; n = 28 for each VM) obtained immediately after evisceration (30 to 40°C). Temperatures were monitored during chilling by thermocouples placed in the center of the thickest portion of each organ, A least squares regression analysis of the heat transfer equation, log₁₀ (T - T₁) = (-t)/f + log₁₀ j (T₀ - T₁), was performed to provide cooling models for various VM organs chilled by HCS or CAC. The heating or cooling rate modulus, f, provided an indicator of rate of cooling. For the HCS, using a propylene glycol solution temperature, T₁, of -9°C, f ranged from -59 for hearts to -168 for livers. For CAC (T₁ = -1°C), f ranged from -102 for kidneys to -340 for livers. These f-values indicate that CAC requires up to three times as long to reduce the product temperature by 90%. A valuable side effect was a reduced shrink (weight loss) for all three VM chilled with the HCS. The percentage shrinks for HCS vs. CAC were 2.28 vs. 3.67 for livers, 2.19 vs. 4.94 for hearts, and 3.50 vs. 4.69 for kidneys. The HCS could provide : (a) more energy and a space efficient refrigeration system, (b) same-day packaging and shipment of certain types of meat such as VM or boneless boxed meat, and (c) a reduction in labor required for multiple handling of meat products by conventional methods.