Dairy Product Quality and Non-Thermal Processing Technologies Geoffrey W. Smithers, Food Science Australia, New South Wales, AUSTRALIA

Consumers demand foods which are safe, nourishing, practical, natural, environmentally friendly, healthy, appetizing, economical and personalized… This represents a real challenge for the industry and calls for innovation and differenti-ation in an extremely competitive environment.

Not only do non-thermal processes improve the microbiological innocuity and quality of a range of products, but they can also be applied in multiple ways throughout the dairy network:

1. To improve the efficiency and end-quality of processing methods; 2. For physical, nutritional and organoleptic features; 3. To preserve unstable bioactive molecules; 4. To modulate enzyme activity; 5. To develop ingredients and hypoallergenic products.

High-pressure processing used to manufacture niche products (yogurt, dairy desserts and smoothies) to control syneresis, produce a firmer texture, increase shelf life, accelerate the aging of cheese, improve the texture of cheese and enhance safety in the raw milk cheese production where regulations allow it. Combined with cold pasteurization, high-pressure treatment maintains the bioactivity of probiotics and of the molecules of milk, colostrum and whey.

Ultrasound treatments are useful in functional applications such as coating, emulsification, encapsulation, cool dehy-dration, viscosity modulation, crystallization management or activation-disactivation of certain enzymes and that, at a moderate cost.

The electric pulse field disactivates natural microflora and allows to lower pasteurization temperature while impro-ving the shelf life of pasteurized liquids. The activity and efficiency of milk’s bioactive molecules (lactoferrin, lactope-roxidase, immunoglobulin) are therefore preserved and the stability of certain proteins is improved when heated. This method is particularly well-suited for the continuous treatment of important volumes.

Cold plasma can be used to coat the surface of foods (dairy or non-dairy) with a film of vitamins or sensitive bioactive compounds. Equally known as the fourth state of matter, cold plasma can be used to disinfect, but it does not pene-trate deeply. It effectively disinfects the irregular surfaces of equipment and packaging.

Alternatives to Thermal Processing: Impact on Product Quality

Session 4

IDF Dairy Science and Technology Week - Quebec 2008

High-Pressure Homogenization as an Alternative to Thermal Treatment to Improve the MicrobialSafety, Shelf-Life and Functionality of Milk and Dairy ProductsFrancesca Patrignani, Alma Mater Studiorum – Bologna University, Department of Food Sciences, ITALY

High-pressure homogenization’s (HPH) ability to disactivate the Listeria monocytogenes and Salmonella enteritidis pathogens in raw milk, and to promote the proliferation and viability of inoculated probiotic bacteria in HPH milk was evaluated. Results show that S. enteritidis is more sensitive to HPH (up to the 4th cycle at 100 MPa) than L. monocytoge-nes (reduction of 5 Log cfu/ml with 8 cycles at 100 MPa). The possibility of producing probiotic cheeses with functional and sensory properties using HPH is greater because the cellular viability of L. acidophilus and of Lb casei is maintained.

Electrodialysis with Ultrafiltration Membrane: A New Way to Fractionate PeptidesLaurent Bazinet, STELA Research Centre/Nutraceutical and Functional Foods Institute (INAF), Laval University, Quebec, CANADA

Electrodialysis with ultrafiltration membrane (EDUFM) is a new technique which isolates fractions enriched with acidic or basic bioactive peptides in a very selective manner. EDUFM has been used to concentrate the sequence of β-lg 142-148 which has anti-hypertensive properties. Results of various tests have shown that increasing the effective membrane surface and the strength of the electric field up to a certain threshold makes it possible to quadruple the concentration ratio of the peptidic sequence. However, increasing flow had no effect on the efficiency of the process but modified the selectivity of the peptides.

Microfiltration and Thermal Treatment for Extending the Shelf Life of Milk: Factors Affecting Product Quality and StabilityVeronika Kaufmann, Munich Technical University, Chair of food process engineering and dairy technology, GERMANY

Microfiltration is a decisive step in the milk sterilization process. This method mechanically eliminates a good part of the bacteria in milk but the morphology of microorganisms limits its efficiency. Combined with thermal treatment, microfiltration extends the shelf life and ensures the safety of milk. However enzymatic reactions can limit the shelf life of microfiltered and pasteurized milk. These occur when raw milk is of lesser microbial and enzymatic quality.

Proteolysis and Lipolysis of Ultra-High Pressure Homogenized Treated Milk During Refrigerated StorageJulieta Pereda, Special Centre for Research in Food Technology (CERPTA), Autonomous University of Barcelona, Bellaterra, SPAIN

The ultra-high pressure homogenization (UHPH) is studied as an alternative to high-pasteurization with similar mi-crobial and physico-chemical characteristics. UHPH of milk increases the inactivation of plasmin in proportion to the pressure exerted. Proteolysis and lipolysis were more intense in milk samples homogenized at the ultra-high pressure of 200 MPa than in samples of milk high-pasteurized or samples UHPH at 300 MPa pressure. Ultra-high pressure homo-genization at 300 MPa could therefore be an alternative to pasteurization.

Alternatives to Thermal Processing: Impact on Product Quality

Session 4

IDF Dairy Science and Technology Week - Quebec 2008