Edwin Ananta

Kinetic studies on high-pressure inactivation of Bacillus stearothermophilus spores suspended in food matrices

Abstract Bacillus stearothermophilus spores ATCC 7953 can effectively be inactivated by high-pressure treatment, but only if it is applied at elevated temperatures; however, these temperatures are much lower compared to the temperature level used in heat inactivation under atmospheric pressure. Temperature and pressure in a range between 60 and 120°C and 50–600 MPa were applied to inactivate spores suspended in mashed broccoli and in cocoa mass. Utilizing an empirical mathematical model, derived from nth order kinetics, the survival curves of the spore strain investigated could be described accurately. The model can predict the impact of combined action of pressure and temperature on spore reduction. It was demonstrated that the inactivation of B. stearothermophilus spores ATCC 7953 improved with increasing treatment intensity. Beside intrinsic microbial inactivation mechanisms, the role of the pressure-induced shift in crystallization temperature of fat on spore inactivation in cocoa mass is discussed.

Comparison of inactivation pathways of thermal or high pressure inactivated Lactobacillus rhamnosus ATCC 53103 by flow cytometry analysis

The effect of thermal and pressure treatments on Lactobacillus rhamnosus ATCC 53103 was evaluated by flow cytometric analysis in conjunction to standard cultivation techniques. A double staining technique with fluorochromes carboxyfluorescein diacetate (cFDA) and propidium iodide (PI) revealed that depending on temperature regime used heat-killed cells had different fluorescence behaviors. Cells killed at 60 degrees C were not stained at all whereas heat treatment at 75 degrees C resulted in a single population entirely labelled by PI. These findings indicated that thermal-induced cell death was achievable with or without membrane degradation. Hydrostatic pressures beyond 400 MPa inactivated L. rhamnosus ATCC 53103 in a different way. It was observed that the irreversible damage of the membrane-bound transport systems could be largely accounted for the cause of high pressure-induced cell death.

Processing Effects on the Nutritional Advancement of Probiotics and Prebiotics

The overall objective of the works performed within PROTECH (Nutritional enhancement of probiotics and prebiotics: Technology aspects on microbial viability, stability, functionality and on prebiotic function, QLK1-CT- 2000-30042) is to address and overcome specific scientific and technological hurdles that impact on the performance of functional foods based on probiotic/prebiotic interactions. Such hurdles include the lack of a clear knowledge of the primary factors responsible for probiotic viability, stability and performance. Limited information is available on the impact of processing, storage and food matrices or food constituents on probiotic viability, stability and functionality. Furthermore, there are insufficient data about the interactions between probiotics and prebiotics in starter cultures or in functional foods prior to consumption. As a result of achieving this objective, selected prebiotics in combination with tailored manufacturing processes can not only contribute to probiotic functionality but also improve viability and stability of probiotic cultures within food matrices during processing and storage.

Whole Grain in Manufactured Foods: Current use, Challenges and the way Forward

ABSTRACT Some countries now incorporate recommendations for increased consumption of whole grain (WG) into local dietary guidelines. Cereal and pseudo-cereal grains are good sources of complex carbohydrates, dietary fiber, proteins, phytochemicals, vitamins and minerals. However, research shows that the large majority of consumers are still falling short of WG consumption goals. To address this, we are actively involved in research to help increase the WG content of processed foods without compromising on taste and texture. In order to ensure consumer trust, the advancement of process technologies in incorporating WG to produce tasty food has to go hand in hand with well designed clinical trials that confirm the health benefits resulting from diets rich in WG.