Abstract
Thermal treatments are widely-used strategies in the food industry to inactivate microorganisms and enzymes in order to guarantee safe products without the need for preservatives, while still prolonging their shelf life. Commercial sterilization usually relies on pressurized hot water or steam, often leading to long process times and to surface dehydration phenomena and overheating. However, from the recent studies in the field of radio frequency heating, it has emerged that food products can be processed with time-temperature regimes that are much milder than those required with conventional techniques, resulting in minimal modification of the sensory and nutritive attributes of the food product itself. In the present work, raw bovine milk was sterilized through a combination of steam and radio frequencies, at various temperatures. Alongside the chemical composition, the pH, acidity, and total mesophilic count have been evaluated before and after the process and at the different exit temperatures, in order to study the impact of this technique on milk quality and safety aspects, during a storage period of 55 days at +4°C. Moreover, the organoleptic properties of milk have been studied using artificial senses coupled with chemometrics. Different temperatures lead to homogenous physicochemical and microbiological results, which conform to those expected for a good quality bovine milk. The assessment of flavor and appearance revealed retained or the minimally modified milk sensorial properties. Therefore, RF heating appears to be a suitable technique for the production of safe milk with a prolonged shelf life up to 40–45 days and without significant alterations of the organoleptic and nutritional attributes.
Highlights
Thermal treatments are common strategies used in the food industry to inactivate microorganisms and enzymes in order to guarantee safe products, replacing the utilization of preservatives, and prolonging the shelf life of food [1]
The aim of this work was to study the impact of different radio frequency (RF) heating protocols on quality and safety aspects of raw bovine milk, using artificial senses coupled with chemometric tools
A lab-scale 2.21 kW dielectric heater, operating at 27.12 MHz, was used to sterilize 1000 L of raw to the product is a parameter set by the operator, while a close loop control optimizes in real time the bovine milk, which was provided from a local manufacturer, and stored at 4 ◦ C
Summary
Thermal treatments are common strategies used in the food industry to inactivate microorganisms and enzymes in order to guarantee safe products, replacing the utilization of preservatives, and prolonging the shelf life of food [1]. To reduce adverse thermal degradation while still ensuring safety for liquid foods, high-temperature short-time (HTST) processes have been developed [2,3,4]. This approach, which relies on pressurized hot water or steam, often leads to low heat-transfer rates [5]. Most food products are dielectric materials, that is, they have poor electrical-conduction properties, which are often associated with a poor thermal conductivity. It would take a long time to heat a dielectric material [6]. The direct interaction between food and electromagnetic energy can significantly reduce the time required to reach the target temperature, leading to an improvement of the organoleptic qualities, the appearance, and the nutritional values
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