Non-thermal food processing: modelling of processes towards safety, quality, and sustainability


There is significant progress and spread of use of non-thermal processing applications in research and industry. United Nations (UN) has issued the 2030. Agenda for Sustainable Development (2015) with 17. Sustainable Development Objectives that should have impact to the development projects and future programs in the world. Regarding those objectives scientists and researchers are starting to use novel techniques in order to obtain valuable output products.

Non-thermal processing techniques include: electrotechnologies, UV light, cold pressure (high pressure processing), hydrodynamic cavitation, ionizing radiation, ozonation, oscillating magnetic fields, pulsed light, supercritical and subcritical fluid processing, biopreservation, electrohydrodynamic processing and electron beam processing.

Technologies such as high pressure, UV light, pulsed light, ozone, power ultrasound and cold plasma (advanced oxidation processes) have shown promising results for inactivation of microorganisms. The purpose of using non-thermal technologies is to assure food safety using shorter processing time, lower energy uptake, lower carbon footprint and lower temperatures. The efficacy of inactivation of microorganisms is greatly enhanced by combination of conventional (thermal) with non-thermal, or non-thermal with another non-thermal technique. The key advantages offered by non-thermal processes in combination with sub lethal mild temperature (<60 oC) can inactivate microorganisms synergistically.

In order to assure food safety mathematical modelling is an essential tool. More specifically, predictive microbiology focusses on the quantitative description of the microbial behavior in food products, for a given set of environmental conditions. Therefore, by combining experimental data, microbial knowledge and mathematical techniques, inactivation following non-thermal technologies can be accurately predicted and controlled.

Predictive models can be classified in different ways: (i) black box (empirical) vs. white box (mechanistic) models, (ii) based on spatial scale (macroscopic- mesoscopic- microscopic models), (iii) based on data collection methods (e.g., viable plate counts, flow cytometry) and (iv) kinetic and probabilistic models.

However, overall quality of food products (juices, nectars, milk etc.) can be deteriorated. The aim of this use of mathematical modelling is use quality index in evaluating effects of each non-thermal technology on quality characteristics of food material that is processed. For that purpose mathematical models for calculating a total quality index (TQI) can be introduced. Mathematical index of TQI in order to evaluate total quality can be calculated.

Several properties of main quality characteristics of juices, beverages, liquid foods and nectars are sensory properties, rheological properties, *Brix, acidity, color etc.. The complexity of food matrix like juices/nectars in relation to various non-thermal treatments (with the purpose of assuring food safety) and quality parameters becomes a challenge for researchers to develop (mathematical) models and analyze data in terms of a quality score.

Quality function deployment (QFD) is another innovative quality tool introduced in Japan in the 60s. It was defined as a "method for developing a design quality aimed at satisfying the customer and then translating the customer's demands into design targets and major quality assurance points to be used throughout the production phase". Its customer centricity to product/process innovation emphasizes its benefit. But even if we assure food safety and preserve food quality we need to take care to have low carbon food print of non-thermal process comparing to traditional one, and to have "zero waste" or to re-use it.

Life Cycle Assessment is the main methodology applied to assess the environmental impact of products and it has been increasingly applied to products of the agri-food. It is a scientific method that includes the following steps outlined in ISO 14040: mapping the process, setting the scope and boundaries, collecting data, calculating, evaluating and interpreting the results with the aim to propose environmental improvements. The LCA, simplified LCA or non-LCA models have the objectives to quantify the environmental performances in the whole food product chain. Regarding the approach three main types occur: LCA, variations of LCA and non-LCA models. Depending on the model, the following criteria apply: (i) if the model is generic or specific for food industry; (ii) if it is user friendly/or not; (iii) if it is free/payable; (iv) if it is focused on one environmental impact or several; (v) besides environment, if it focuses on some other sustainability dimension (economic, social) (vi) if it requires specific environmental knowledge, etc. LCA has great potential for driving the development of products and processes. Through LCA novel processing can be compared with existing commercial alternatives and environmental hotspots can be also identified.

For non-thermal technologies, when they are evaluated from an environmental point of view there are many difficulties like lack of real data for the inventory phase (lab scale information or theoretical data) and the definition of the novel foods, since new products or processes might have unique properties. Therefore, there is need for an approach for the environmental analysis of non-thermal food technologies. Through evaluating environmental impacts through LCA of some traditional and novel food preservation technologies, we can contribute to the development of more sustainable food products. Some general improvements can be defined towards environmental issues in order to select the more adequate preservation method when designing new food products.

By performing modelling and optimization of non-thermal processing and subsequent sustainability evaluation approach (life cycle assessment) it will be feasible that this approach allows minimization of environmental impact as well as significant reduction of energetic needs. The whole picture needs to be looked from fundamental approach (basic interdisciplinary science), raw materials, through processes and technologies, and then to final product taking care of waste (by-product) and management for its re-usage. Usage of non-thermal processing and their combination (synergy) will ultimately focus of reduction of waste and energy necessities while producing high quality products with minimal environmental and naturally social impact. Scientists need to assure e3 (ecologic, economic and environmentally friendly) non-thermal process in order to assure safety, quality, and sustainability.

Curriculum Vitae

Anet Režek Jambrak, Associate professor, was born on 26 December 1980. in Zagreb. She graduated from the Faculty of Food Technology and Biotechnology of the University of Zagreb in 2002. and in year 2008. she defended her doctoral dissertation (thesis) titled "Influence of Ultrasound on Physical and Functional Properties of Whey Protein" She was employed at the same faculty as a young researcher (junior assistant) in 2003 in Department of Food Engineering, Laboratory for Food Process Engineering. She became Associate professor (habilitated) in 2009 in the scientific field of Biotechnical Science, Food Technology. In 2010. she became a senior research associate. According to the decisions of the Biomedical Sciences Committee, she was titled Scientific Research Officer on 18 January 2011, and in the position of Scientific Advisor (permanent title) on 24.11.2017. She became Associate professor in 2013 at the same Faculty. Since 2003 he has been participating in undergraduate, undergraduate and graduate education modules: Physical Properties of Complex Food Systems, Food process engineering, Processes for Food Conservation, Processes for Food Preparation and Novel Food. She has been participating in postgraduate teaching since 2014. In 2017 she introduced the English language module titled "Innovative Non-Thermal and Thermal Food Processing Techniques" and a module "Sustainable Food Processing Techniques and Agro-Food Byproducts". Under her mentorship, 19 BSc, 16 MSc thesis were defended and she was co-mentor of two doctoral dissertations. She also has strong international collaboration with renowned scientists. She was trained abroad in 2005. at the Faculty of Health and Life Sciences at Coventry University, UK through the scholarship "British scholarship trust" and in 2009. at the University of Avignon, France, as a invited lecturer and researcher in the field of "green" ultrasound and microwave extractions.

In the period from 2007. Anet Režek Jambrak has published over 80 significant scientific papers, published in top scientific journals with high impact factors (citation more than 1100, h-index 18). She is also a co-author of 10 chapters in scientific books, most of which are renowned world publishers Elsevier, Springer, Wiley-Blackwell and Nova Science Publisher. Papers and chapters in the book are dealing with research and application of the results of scientific-research work in the field of non-thermal and advanced heat processing in food processing. She is also a member of the editorial board in 19 international, and associate editor in 2 international scientific journals. She is the winner of many awards and acknowledgments, most notably the 2016. Young Scientist Award from the International Union of Food Science and Technology (IUFOST). In 2011. she received award for Young Scientist "Vera Johanides" from Croatian Academy of Engineering and 2009. State Prize for Science for Young Scientists awarded by the Parliament of the Republic of Croatia and the Government of the Republic of Croatia. Since 2016. she is a member of the International Academy of Food Science and Technology (IAFST) - Early Career Scientist.

Dr. Anet Režek Jambrak
Umiversity of Zagreb Faculty of Food Technology and Biotechnology Department of Food Engineering. Laboratory for Food Processes Engineering Zagreb, Croatia