RESPONSE TO STRESS CONDITIONS OF MICROORGANISMS TREATED WITH NATURAL ANTIMICROBIALS IN CHEESE WHEY

M. VON STASZEWSKI, R. JAGUS, S. MUGLIAROLI, L. HERNAEZ, G. LEHRKE

Food Engineering

Nova Science Publishers, Inc

Año: 2011; p. 249 - 271

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-MX; mso-fareast-language:ES-MX;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} -->  Cheese whey is a by-product that recently has gained attention because it represents a source of food ingredients of high nutritive value. It is generally processed by ultra filtration and spray drying to produce whey powder and protein concentrates. However, the concentrated fluid obtained from the membrane process could be use directly in the formulation of foods if it maintains a proper microbial stability, avoiding the drying process which results rather expensive and affects the nutritional and functional properties. Food-processing methods have been developed to interfere with bacterial homeostasis, prevent growth, or kill food-borne pathogen. The growing demand for fresh, minimally processed foods by consumers had led to the need for natural food preservation methods such as the use of natural antimicrobials and combination with other hurdles, without adverse effects on the consumer or the food itself. Additionally, natural antimicrobials can be used alone or in combination with other non-thermal technologies, but it has also been demonstrated that microorganisms can display tolerance to these factors when they are applied in sub-lethal concentrations. Thus, it may be useful to assess whether pre-treatments with natural antimicrobials like green tea extract, MicrogardTM or nisin, would enhance sensitivity or resistance of food-borne bacteria to different stress conditions, such as acidity, low temperatures and salt addition, which are commonly applied in food-processing methods. For this purpose different techniques were used in order to evaluate possible membrane damages produced by the combined treatments. The results of this study revealed that the bacterial reduction when applying stress conditions was improved in most of the cases after exposure to natural antimicrobials in liquid cheese whey. Synergistic effects are important to minimize the concentration of additives required to achieve a particular antibacterial effect without adversely affecting the sensorial acceptability. This knowledge about the interactions between natural antimicrobials and stressors has important implications for the food industry when considering which food preservation regime is the best to adopt.