Advancing the Role of Food Processing for Improved Integration in Sustainable Food Chains

Food scientists need to work together with agriculturists, nutritionists, civil society, and governments to develop an integrative approach to feed a growing population sustainably. Current attention on food sustainability mainly concentrates on production agriculture and on nutrition, health, and well-being. Food processing, the necessary conversion of raw materials to edible, functional, and culturally acceptable food products, is an important link between production and consumption within the food value chain. Without increased attention to the role of food processing for a maintainable food supply, we are unlikely to succeed in addressing the mounting challenges in delivering sustainable diets for all people. The objective is to draw on multidisciplinary insights to demonstrate why food processing is integral to a future food supply. We aim to exemplify the importance of essential relevant sustainability indicators and impact assessment for developing informed strategies to feed the world within planetary boundaries. We provide a brief outlook on sustainable food sources, review food processing, and recommend future directions. We highlight the challenges and suggest strategies for improving the sustainability of food systems, to hopefully provide a catalyst for considering implementable initiatives for improving food and nutrition security

Physiological analysis oflactobacillus rhamnosusVTT E‐97800 : Adaptive response to osmotic stress induced by trehalose

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Purpose – This paper aims to describe the physiological analysis of L. rhamnosus VTT E‐97800 and its adaptive response to osmotic stress induced by trehalose. Design/methodology/approach – Cells of L. rhamnosus E800 in the stationary phase of growth were subjected to osmotic stress induced by trehalose treatments. The effects of osmotic stress on the viability of the study strain were determined by conducting flow cytometric analysis with carboxyfluorescein diacetate (cFDA) and propidium iodide (PI) and by observing the corresponding cells growth on MRS agar plates. Osmotic‐induced changes of esterase activity and membrane integrity were monitored. Ability to extrude intracellular accumulated cF (additional vitality marker) was taken into consideration. Findings – The fluorescence‐based approach gave additional insights on osmotic induced changes of cellular events, which could not be explicitly assessed by culture techniques. Trehalose treatments caused a transient membrane permeabilization as revealed by a gradual decrease in esterase activity (a measure of enzyme activity and thus of viability) with increase in trehalose molarity. However, culturability on MRS agar was not significantly affected. Membrane integrity was maintained and there was an improvement in the ability of cells to extrude intracellular accumulated cF. Originality/value – The paper provides a comparative study of the conventional culture techniques and the flow cytometric viability assessment which showed that esterase activity cannot be relied on to ascertain the culturability and viability status of an organism

Cellular injuries on spray‐dried Lactobacillus rhamnosus GG and its stability during food storage

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Purpose: This paper aims to evaluate the cellular injuries associated with spray‐drying of Lactobacillus rhamnosus GG (LGG) in trehalose/monosodium glutamate (MSG) media by means of flow cytometry measurements; and also whether, and to what extent, the probiotic remain stable and viable in food formulations. Design/methodology/approach: Spray‐drying was applied in the production of trehalose‐based preparations containing LGG. To gain more insights on the cellular damages that must have occurred during drying, flow cytometric analysis was applied in combination with carboxyfluorescein diacetate (cFDA) and PI stains. Spray‐dried samples were observed by scanning electron microscopy (SEM). The storage stability of spray‐dried LGG was monitored in food samples over a period of time. Findings: It was observed that during spray‐drying, 1.80×109 CFU/ml viable counts, which were equivalent of 68.8 per cent cells, were recovered in trehalose matrices but on incorporating 12.5 g/l MSG as a carrier component, survival rates were significantly improved. Density plot analysis showed a higher degree of membrane damage in cells spray‐dried in trehalose without MSG. SEM revealed no difference in the shapes and surfaces of spray‐dried samples. Evaluation of the recovery rates of LGG, initial count of ~109 CFU/ml or g, at storage time intervals revealed a minimum level of ~105 CFU/ml in apple juice after 12 days and ~107 CFU/g in chocolate beverages after ten weeks

The Influence of Sugars on Pressure Induced Starch Gelatinization

AbstractBesides the application of high pressure (HP) as a non-thermal preservation technology, HP could additionally have a deep impact on the material properties of the treated food. Especially the HP induced swelling and gelatinization of starch influences the processing properties of starch-based food systems and differs in comparison to thermal induced gelatinization. The aim of this study was to examine the impact of HP on starches under different conditions and to influence systematically the gelatinization and pasting properties of wheat starch by the addition of various types of sugar. Caused by limitation of conventional methods, this study also includes the development of an appreciate method based on the particle size measurements of the starch granules. Three methods of measuring particle sizes were examined for an application for pressure treated starches. Finally, an image analysis with microscope, camera and image processing software ImageJ was chosen to perform the analysis. Wheat, tapioca and potato starch with concentration of 5 (w/w) and 25 (w/w) were pressurized at 600MPa for ten minutes at 20°C as well as 60°C, to reach treatment conditions which are suitable for HP food pasteurization. The results showed that ultra HP significantly increased the particle size of the starch granules, whereas the degree of swelling was starch type and temperature dependent. High starch concentrations resulted in a limited swelling caused of the limited water content. This effect is enhanced with increasing swelling properties. Besides this, sugar caused a significant decrease of the granules size. A dependence of this effect with the type of sugar was not examined. This work should be a contribution to expand the understanding of the swelling mechanisms of starch granules under HP and should facilitate a future process and product development of HP pasteurized starch based products

Flow cytometry assessment of Lactobacillus rhamnosus GG (ATCC 53103) response to non‐electrolytes stress

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Purpose – Lactobacillus rhamnosus GG, a probiotic of human origin, known to have health beneficial effects can be exposed to osmotic stress when applied in food production as important quantities of sugars are added to the food product. The aim of this study is to assess the mode of action of nonelectrolytes stress on its viability. Design/methodology/approach – Investigations were carried out on stationary phase cells treated with 0-1.5 M sugars, by means of flow cytometric method (FCM) and plate enumeration method. Osmotically induced changes of microbial carboxyfluorescein (cF)-accumulation capacity and propidium iodide-exclusion were monitored. The ability of the cells to extrude intracellularly accumulated cF upon glucose energization was ascertained as an additional vitality marker, in which the kinetics of dye extrusion were taken into consideration as well. Sugar analysis by HPLC was also carried out. Findings – The results of FCM analysis revealed that with sucrose, only cells treated at 1.5 M experienced membrane perturbation but there was a preservation of membrane integrity and enzymatic activity. There was no loss of viability as shown by plate counts. In contrast, the majority of trehalose-treated cells had low extent of cF-accumulation. For these samples a slight loss of viability was recorded on plating (logN/No 0.45). At 0.6 M, cells had similar extrusion ability as the control cells upon glucose energization. However, 20 per cent of sucrose-treated cells and 80 per cent of trehalose-treated cells extruded the dye in the first 10 min. Originality/value – This finding pointed out the importance of trehalose to enhance the dye extrusion activity, which is regarded as an analogue of the capability of cells to extrude toxic compounds. Sugars exert different effects on the physiological and metabolic status of LGG but none caused a significant viability loss. LGG can be a choice probiotic bacterium in sugar-rich food production e.g. candies, marmalade etc., in which exposure to high osmotic pressure is be expected

Sterilization of liquid foods by pulsed electric fields – an innovative ultra-high temperature process

The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm−1), skim milk (0.3% fat; 5.3 mS cm−1) and fresh prepared carrot juice (7.73 mS cm−1). The combination of moderate preheating (70–90°C) and an insulated PEF-chamber, combined with a holding tube (65 cm) and a heat exchanger for cooling, enabled a rapid heat up to 105–140°C (measured above the PEF chamber) within 92.2–368.9 μs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using computational fluid dynamics (CFD). A preheating of saline water to 70°C with a flow rate of 5 l h−1, a frequency of 150 Hz and an energy input of 226.5 kJ kg−1, resulted in a measured outlet temperature of 117°C and a 4.67 log10 inactivation of B. subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for G. stearothermophilus spores in saline water. A preheating to 95°C and an energy input of 144 kJ kg−1 resulted in an outlet temperature of 126°C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10) was achieved during the thermal treatment. Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring inhomogeneous temperature fields

Transition from van-der-Waals to H Bonds dominated Interaction in n-Propanol physisorbed on Graphite

Multilayer sorption isotherms of 1-propanol on graphite have been measured by means of high-resolution ellipsometry within the liquid regime of the adsorbed film for temperatures ranging from 180 to 260 K. In the first three monolayers the molecules are oriented parallel to the substrate and the growth is roughly consistent with the Frenkel-Halsey-Hill-model (FHH) that is obeyed in van-der-Waals systems on strong substrates. The condensation of the fourth and higher layers is delayed with respect to the FHH-model. The fourth layer is actually a bilayer. Furthermore there is indication of a wetting transition. The results are interpreted in terms of hydrogen-bridge bonding within and between the layers.Comment: 4 pages, 3 figure

Impact of different water activities (aw) adjusted by solutes on high pressure high temperature inactivation of Bacillus amyloliquefaciens spores

Much research has been conducted to comprehend the mechanisms of high pressure (HP) inactivation of spores in aqueous systems but for food model systems these information are scarce. In these systems spores can interact with ingredients which then could possibly lead to retarded or reduced inactivation, which can cause a problem for the sterilization process. The protective mechanism of a reduced aw-value is still unclear. HP processing might prove valuable to overcome protective effects of solutes and achieve shorter process times for sterilization under HP. To gain insight into the underlying mechanisms five aw-values (0.9, 0.92, 0.94, 0.96, 1) were adjusted with two different solutes (NaCl, sucrose). Solutions were inoculated with spores of Bacillus amyloliquefaciens and treated at 105, 110, and 115°C at 600 MPa. Further a thermal inactivation was conducted at the same temperatures for a comparison with the HP data. Afterward, the influence of HP high temperature treatment on the inactivation, the dipicolinic acid (DPA)-release and membrane constitution was assessed by plate count, HPLC and flow cytometry (FCM). The results show that during HP treatments sucrose and salt both have a protective effect, in which the influence of sucrose on the retarded inactivation is higher. The threshold water activities (aw), which is 0.94, here salt and sucrose have a significant influence on the inactivation. The comparison of thermal (105–115°C) and HP and high temperature (600 MPa, 105–115°C) treated samples showed that the time needed to achieve a 4–5 log10 inactivation is reduced from 45 (aw = 1) to 75 (aw = 0.9) min at 105°C to 3 (aw = 1) to 15 (aw = 0.9) minutes at 600 MPa and 105°C. The release of DPA is the rate limiting step of the inactivation and therefore monitoring the release is of great interest. The DPA-release is slowed down in high concentrated solutions (e.g., sucrose, salt) in comparison to aw 1. Since there is a difference in the way the solutes protect the spore it could be seen as an inner spore membrane effect. Maybe as shown for vegetative microorganism the solutes can interact with membranes, e.g., the inner spore membrane. Flow cytometry (FCM) measurement data show a similar trend

Recommendations guidelines on the key information to be reported in studies of application of PEF technology in food and biotechnological processes

The application of pulsed electric field (PEF) technology as a non-thermal cell membrane permeabilization treatment, was widely demonstrated widely to be effective in microbial inactivation studies, as well as to increase the rates of heat and mass transfer phenomena in food and biotechnological processes (drying, osmotic treatment, freezing, extraction, and diffusion). Nevertheless, most published papers on the topic do not provide enough information for other researchers to assess results properly. A general rule/guidance in reporting experimental data and most of all exposure conditions, would be to report details to the extent that other researchers will be able to repeat, judge and evaluate experiments and data obtained. This is what is described in the present recommendation paper. Industrial relevance: Pulsed electric field (PEF) treatment is a promising technology that has received considerable attention in food and biotechnology related applications food and biotechnology related applications of PEF include: i) “cold” pasteurization of liquid foods and disinfection of wastewater by microbial inactivation ii) PEF-assisted processing (drying, extraction or expression