Technology News from SIK

Nils Bengtsson

Processing

The novel Q EU project
The aim of the Novel Q project has been to formulate integrated strategic solutions for technical and basic research hurdles for complex, real food products. In order to demonstrate to participating industry the processing technologies studied in Novel Q, funds have been allocated for a number of short-term demonstration trials. These trials involve the technologies of ohmic heating, pulsed electric field (PEF) processing, cold plasma, high pressure sterilisation, microwave heating and robot handling of delicate foods.

Trials to be carried out at SIK comprise high pressure processing of cereal grains, continuous (in pipe) microwave heating of fish products, microwave-assisted drying of waste products and roasting of flex seed, as well as robot handling of vegetable products.

Literature reviews on fruit drying and bread baking
Two literature reviews have been reported as part of the doctorate projects of Maria Eduardo and Isabel Guiamba, Mozambique, at the Department of Chemical and Biological Engineering Food Science at Chalmers Technical University, with Lilia Ahrné, SIK, and Ulf Svanberg, Chalmers University of Technology, as supervisors.

Drying techniques for fruit processing: This literature review, by Isabel Guiamba, presents an overview of different drying methods and recent research in microwave related dehydration of fruits and vegetables, and the resulting effects on quality and nutritional aspects. The objective has been to identify an appropriate fruit drying technology for processing indigenous fruits in Mozambique, such as massala, maphilwa and jambalau, but also mango and papaya. The background is that people in sub-Sahara Africa frequently have to rely on indigenous plants and fruits as food resources under critical periods of food supply. However, a high proportion of these sources are lost, due to postharvest waste. Therefore, the processing of produce, using low cost processing techniques, can be very important to minimise losses and extend availability off season. Conclusions from the review are that microwave related drying seems to offer advantages in terms of drying time and quality at a reasonable cost. However, information about microwave drying effects on nutritional aspects for dried fruits is incomplete, suggesting further studies are required. A comparative study of microwave assisted convection drying, convective hot air drying and solar drying is recommended, studying also effects on sensory and structural / textural properties, rehydration and nutritional characteristics for different processing parameters and pretreatments.

Effects of ingredients in bread manufacturing: According to the report by Maria Eduardo, bread is an ideal functional food product and an important part of the diet in most parts of the world, due to high availability, high nutritional value and low cost. Bread baking from wheat flour is becoming increasingly popular, also in Africa, due to the superior baking potential of wheat and its gluten protein. But wheat has to be imported, and it is therefore highly desirable that the expensive import could be reduced by partial or complete substitution of wheat with local products, such as maize, sorghum or sweet potato and cassava, if the protein and starch components of the substitute could provide a structure to compensate for the lower gluten content.

In the literature study, the effects of ingredients in bread manufacture as well as the different steps in the bread making process are reviewed. For the various flours, protein and starch characteristics are studied as well as the effect of other ingredients and additives (sugar, salt, lipids, emulsifiers and enzymes). The bread making process is studied with regard to mixing, fermentation and the baking process, taking into account oven design, bread type and sample size, as well as the conditions of time, temperature and humidity and their influence on bread quality.

The objective of the literature study has been to form a basis for planning experimental work aimed at finding solutions for producing an acceptable bread quality, without using wheat flour, or with a minimum of it.

Packaging

Antimicrobial packaging
In the January 2009 issue of SIK Technology News, a brief presentation was given of a 3-year EU project, titled “Natural antimicrobials for innovative and safe packaging”, of the acronym NAFISPACK. One of the aims of this project is to develop antimicrobial active packaging and intelligent packaging. Targeted products are fresh fish, chicken and minimally processed cut vegetables. The role of SIK in this work is to ascertain that suitable parameters are chosen for each of the three types of food, and that the selected quality parameters are maintained.

The work now reported by Tim Nielsen, SIK, and Manuela Rollini, University of Milan, has comprised literature studies combined with storage experiments, in which SIK has carried out the chemical and sensory testing and Manuela Rollini the microbiological work. The title of the report now available is “Selection of suitable quality parameters of each of the three selected food types”.

In the experimental work with vegetable salad mixes, fresh chicken legs and diced fresh salmon fillets, samples were sent by refrigerated transport from the participating partners at Verdifresh, Nutreco and Lachskontor, to SIK and the University of Milan for their respective storage studies and analytical work. The objective of this part of the project was to determine the critical quality factors from a chemical, sensorial and microbiological viewpoint for each of the three products.

Vegetable mixed salad: The vegetable mixed salad consisted of cut iceberg lettuce, shredded carrots and shredded cabbage and was packed in anti-mist OPP bags and sealed, after flushing with an MAP gas. Analyses were performed, after one to eleven days of chilled storage, by GC headspace analysis and MS, measuring also headspace gas composition for oxygen and carbon dioxide, and by sensory analysis by experienced panellists, judging visual appearance, smell and texture of the samples. Enumeration of the microbial population was made up to 9 days of storage at 4°C. The expected shelf life of 7 days (from literature and prior experience) correlated well with the results from the storage tests. From a sensory perspective, it was primarily the smell that caused rejection, but visual appearance was also poor after 7 days. The microbiological results showed that aerobic mesophiles and aerobic psychrotrophs reached unacceptable levels on day 6, at which point the lactic acid bacterial count was also high. Possible chemical spoilage indicators found included acetaldehyde, ethanol, ethyl acetate and dimethyl sulphide.

Chicken legs: The chicken legs were packed in a PET tray and thermosealed with PET film and stored for up to 15 days at 4°C. The sensory scores of the chicken samples were within the acceptable limits on day 12, but the smell had deteriorated below acceptable limits on day 15. Lactic acid bacteria grew at the fastest rate of the microorganisms and were considered to be the most likely source of microbial decay, although the population was still only about 6 log cfu/g on day 11. The most promising chemical indicator of spoilage was pentanal, a product of lipid oxidation processes.

Diced salmon fillet: The fresh salmon cubes were packed in PA/PE bags in a vacuum packaging machine and stored at 0 to 2°C for up to 9 days. The salmon samples did not show any microbial spoilage during this period. Sensory scores were, however, below acceptable limits after 4 days, and after 6 days the smell was very foul. Possible chemical indicators of spoilage included acetaldehyde, ethanol, 3-hydroxy-2 butanone and isopentyl alcohol.

Microbiology

SIK presentations at the Congress of European Microbiologists

Gene expression in L. monocytogenes after PEF processing: The presentation by Maria Lövenklev, titled “Investigation of the gene expression in Listeria monocytogenes after pulsed electric field processing” was co-authored by Pernilla Arinder and Elisabeth Borch, all from SIK. The objective of the work was to study the gene expression after three different PEF treatments in phosphate buffer: 35 kV, 6 µs, 3 pulses; 35 kV, 6 µs, 5 pulses; and 32 kV, 10 µs, 5 pulses. Samples were collected after 6, 15 and 20 min post PEF. Developed quantitative reverse transcription PCR specific for rpoB and opuCA was used to investigate the gene expression.

The highest reduction (1.5 log cfu/mL) of L. monocytogenes was achieved when applying a PEF treatment of 32 kV/cm, 10 µs and 5 pulses. After this treatment, the rpoB expression was slightly down regulated during 20 min after PEF. The opposite effect was, however, observed after the other two PEF treatments: 35 kV, 6 µs, 3 pulses and 35 kV, 6 µs, 5 pulses. Here, the rpoB expression was up regulated, with the highest expression observed after 15 min. At this time, the expression had increased 6-fold compared to untreated cells. Also, after 20 min the rpoB expression was still high; between 4-6 times higher than for untreated cells. Work is in progress to analyse the opuCA expression.

Conclusions are that different PEF treatments affect the rpoB expression and subsequently the protein synthesis in L. monocytogenes differently.

Restraining bacterial adhesion to titan surfaces: In a presentation by Josefin Caous, co-authored by Maria Lövenklev and Maud Langton, SIK, and J. Fäldt, Nobel Biocare AB, early work within Josefin's licentiate project was presented, titled “ Restraining bacterial adhesion to titan surfaces by manipulating environmental factors”. The project is funded by the KK foundation and Nobel Biocare AB in collaboration with Chalmers University of Technology and SIK.

Dental implant materials have been developed with excellent osseo integrating capabilities. However, while these materials integrate well with human cells, they also provide good surfaces for the adherence of bacteria. The project objective is to identify the influence of environmental factors on bacterial adhesion, such as pH, nutrients and available oxygen,. and to investigate if such adhesion can be restrained by manipulating these factors. In the work, mono-and mixed cultures of bacteria will be cultivated under different controlled environmental conditions. Physical and morphological responses will be analysed by Confocal Laser-Scanning Microscopy (CSLM), using fluorescence labelled bacteria.

Results from earlier studies indicate that changes in growth conditions, such as variation in carbon source, pH and sodium levels, influence the ability of bacteria to adhere to saliva-treated hydroxyapatite. This can be related to changes in composition of the bacterial cell wall and cell-surface proteins, which will be explored during this project. Work is in progress to further investigate the possibility to influence bacterial growth and adhesion by manipulating their microenvironment.

Effect of basic PEF processing factors on microorganisms, enzymes and microstructure in liquid whole egg and low fat milk

This is the title of a new report within the EU HighQ RTE project on non-thermal processing technologies, authored by P. Arinder, M. Lövenklev, F. Alm and E.Borch, SIK, I. Perez-Munuera, Universidad Politécnica de Valencia and P. Saracino, CAMST, in which SIK have been responsible for the microbiological work.

The objective has been to evaluate the effect of basic PEF factors such as electric field strength, energy input, pulse length and number of pulses on the inactivation of a selection of bacteria regarded as hazards in ready-to-eat (RTE) foods. The pathogens L. monocytogenes and Salmonella spp. were studied. Treatment was performed in phosphate buffer, liquid whole egg and low fat milk, determining the quality of the liquid egg.

Small scale pilot equipment was used for all PEF experiments, applying batch treatment in a closed treatment chamber of new design, which enables equal treatment of the entire sample, maintaining a temperature below 50°C. The microstructure and the enzymatic activity of liquid whole egg were studied as well, in not inoculated samples. Before treatment, the product was kept cold, measuring temperature before and after PEF treatment, monitoring temperature increase.

Treatment in the PEF chamber gave a reduction below 3 log cfu/mL of L. monocytogenes, S. enteritidis and S. senftenberg when maximising the product temperature to 50°C. Consecutive PEF treatments with cooling in between were required to further increase the bacterial reduction. Using PEF treatment at 32 kV/cm during 50 µs applied as 5 pulses with cooling in between reduced S. senftenberg by 5 to over 7 log cfu/mL compared to 3-5 log cycles reduction of L. monocytogenes.

Both bacteria were found more sensitive to PEF treatment in milk than in phosphate buffer with similar pH and conductivity, demonstrating reduction of L. monocytogenes in phosphate buffer as a function of PEF treatment variables and 1,2 and 3 treatment cycles.

No activity of proteolytic enzymes was observed in PEF treated samples, nor hydrolysis or oxidation activities in the lipid fraction. After one week of storage, no changes were observed in the protein solubility of non-homogenised PEF treated samples. However, homogenisation led to a protein insolubilisation effect, probably caused by the homogenisation itself. Microstructural studies showed a highly affected lipoprotein matrix in whole liquid egg treated by PEF, with broken continuity of the protein network and some degradation of protein granules from the yolk.

From a chemical point of view PEF treatment does not destabilise the liquid whole egg, but the microstructural components are affected, which could affect the functionality of foodstuffs when liquid whole egg is used as a raw material.

Antimicrobial effect of benzoic and sorbic acids against Zygosaccharomyces bailii

Helena Oscarsson has presented her masters thesis titled“The positive antimicrobial effect of benzoic acid and sorbic acid agains Zygosaccharomyces bailii in an environment of different values of pH, sugar and temperature” at Sahlgrenska Academy, University of Gothenburg. The work has been carried out at SIK, supervised by Elisabeth Borch and Bitgitta Bergström, SIK.

In the project, the effect on growth of Z. bailii from different combinations and concentrations of benzoic acid and sorbic acid was investigated at different combinations of pH, temperature and sugar content. The objective was to determine the effectiveness and importance of these preservatives relative to environmental factors. In total, 54 different combinations of preservatives, pH, temperature and sugar content were examined, assessing growth of Z. bailii by Bioscreen C. The inhibiting effect of benzoic and sorbic acids was very good. In fact, growth was seen in only one of the combinations tested containing the preservatives, suggesting that the time for measurements should be extended and/or more concentration levels included.

Structure and material design

Foam materials based on maize protein

Zein proteins are by-products, for example in ethanol production from corn, where the starch is converted to ethanol through enzymatic and biological treatment, and in the milling industry (bran). Therefore the use of zein in production of foam material would not compete with food production.

The main objective of the project has been to find a good combination of zein protein and plasticisers and a suitable way to form foams. The mixture of zein, its solvent and plasticiser (resin) was investigated with regard to viscosity and strain hardening in order to find resins with the desired physical properties for foaming. The mixture was placed in an aluminium vessel inside an oven set at 175°C for 20 minutes. The use of plasticiser increased the porosity, decreased the Young's modulus, absorbed energy and reduced the stress level in compression tests. Resin concentrations above 10% failed to produce foams. The foams were analysed regarding their structure, density and mechanical properties.

The results indicate that biodegradable foamed materials with the desired properties for protective packaging can be produced from zein.

Joint workshop BIOMATCELL, SuMo Biomaterials, BIOSUM

The SuMo Centre of Excellence on supramolecular materials was presented in the April 2009 issue, and the BIOSUM research school in biomaterials in the October 2008 issue of SIK Technology News. BIOMATCELL is another VINN Excellence Centre in Gothenburg which focuses on structure dynamics and properties of biomaterials and cell therapy.

The joint workshop took place on 22-24 June at Fiskebäckskil, on the Swedish west coast, comprising presentations and discussions on strategies, communication, leadership and team building, with the participation of the international advisory committee and representatives of the companies involved in the centre.

For more information about SuMo Biomaterials projects, organisation, partners, publications and the Biosum research school, go to http://www.chalmers.se/chem/sumo-en/

Determination of local diffusion properties in heterogeneous biomaterials

This paper by Niklas Lorén, published in Advances in Colloid and Interface Science and co-authored by Magnus Nydén, Chalmers University of Technology, and Anne-Marie Hermansson, SIK, discusses the coupling between structure and diffusion properties, which is essential for the functionality of heterogeneous biomaterials.

Molecular diffusion in heterogeneous biomaterials is of great importance for many industrial applications, for example to protect sensitive substances in foods, in the release of oral taste substances or active components in medicines, to avoid redistribution of water in processed food and to the water holding ability of foods and hygiene products.

In the paper, structural heterogeneity is defined, and its implications for time-dependant diffusion are discussed, and the relevance of length scales is exemplified for heterogeneous biomaterials such as gels, emulsions, phase separated biopolymer mixtures and chocolate. Structural heterogeneity is inherently related to the different typical length scales present in the biomaterial and its spacial distribution in the structure. It also directly influences the diffusion, depending on the time-scale of the diffusion process.

Different techniques for measuring diffusion properties at different length and time scales are presented. The interplay between the local and global diffusion properties are discussed, the two being strongly related to each other.

New techniques have emerged to measure simultaneously both structure and local diffusion properties, of which emphasis is given to FRAP( fluorescence recovery after photo bleaching). FRAP, in combination with different microscope stages, permits determining mass transport properties during dynamic changes of the structure, and opens up possibilities to reveal connectivity between different regions in heterogeneous biomaterials. The FRAP method is reviewed and its use in heterogeneous biomaterials is discussed.

It is concluded that structure design is vital for the control of diffusion in heterogeneous biomaterials.

Studying local diffusion in heterogeneous materials by FRAP

At the ISFRS symposium on Food Rheology and Structure in Zürich, Joel Hagman presented a poster titled “Determining local diffusion properties using most likelihood evaluation of fluorescence recovery after photobleaching data”, co-authored by Niklas Lorén and Anne-Marie Hermansson, SIK, and Jenny Johansson, Mathematical Sciences, Chalmers University of Technology.

In heterogeneous systems, local variation in diffusion is a possibility. It is important therefore, not to average the diffusion but to measure locally. This can be done by the use of a confocal laser scanning microscope in combination with fluorescence recovery after photobleaching.

The data evaluation of FRAP is usually done by averaging the image intensity in the bleached region of interest and fitting its recovery. The approach is rather fast and easy to implement, but has low accuracy. It is only with recent models that the error is sufficiently low to yield a reliable result when averaging the information.

Using instead the maximum likelihood (ML) approach to data evaluation, the pixel information is not averaged. Instead all the information is used in the image data set. The noise is modelled and accounted for, and the fitting process is done by estimating the most likely values of the fitted model parameters. The procedure used is described and the two models for ML evaluation, the Gaussian and the Monotone ML models, are presented.

It is concluded that the most likelihood framework offers:

• high accuracy estimates of local diffusion coefficients;
• error estimates of each fitted model parameter;
• demands less bleaching, which makes FRAP available for more sensitive materials; and
• diffusion coefficient determination in both homogeneous and heterogeneous materials.

In-line rheometry by UVP-PD technique

Also at the ISFRS symposium in Zürich, Johan Wiklund, SIK, presented a paper titled “ Application of ultrasound Doppler based in-line rheometry method to complex process streams”, co-authored by Mats Stading, SIK. An overview was given of developments in the field over the past decade, followed by examples of industrial applications. A method for in-line rheometry, combining the Doppler-based ultrasound velocity profiling (UVP) technique, with pressure difference (PD) measurements has been developed and validated at SIK. The UVP-PD method has now been applied to measure the rheology of several foods and other industrial suspensions directly in-line under industrial processing conditions, such as heat treatment, crystallisation and liquid displacements. The UVP-PD method was validated using conventional off-line rheometers, and the agreement between measured and simulated data for velocity profiles, rheological data and time-temperature profiles was found to be excellent.

The UVP-PD method developed was found to be a powerful tool for non-invasive visualisation as well as rheological in-line characterisation of real foods and industrial suspensions. Fast transient processes, such as liquid displacement of model and industrial fluids in pipes, can be monitored in-line, in real-time using the UVP-PD method. The transition from one fluid to another could be monitored both in terms of changes in the shape of the velocity profile and in rheological parameters.

Fat migration, fat bloom and cracking in chocolate pralines – A literature review

As part of her doctorate work within the EU ProPralin project, Lina Svanberg has completed a comprehensive literature review of the above title, based on 110 publications, dating from 1967 to 2008. The aim of the ProPralin project is to find new means for European SMEs (Small and medium enterprises) to avoid fat bloom and crack formation in chocolate pralines, the two major issues limiting their shelf life. The objective of this review is, in consequence, to elucidate what is available in the literature on the mechanisms behind fat migration, fat bloom and crack formation and to evaluate different preventive techniques and analytical methods.

This 90 page review gives a thorough description of the praline system and the manufacturing process, defines fat polymorphism, fat bloom and particle size distribution and proceeds to present the mechanisms involved in fat migration and how this relates to microstructure and the factors influencing fat migration and fat bloom. The mechanisms of cracking are discussed and the interface between shell and filling, and different means of preventing liquid lipid migration. Finally, methodologies are described, with emphasis on modern methods so far not commonly used in the chocolate field, such as CLSM and DMA, that may facilitate solving the problems of fat bloom and shell cracking.

The author concludes that fat migration and fat bloom have been widely debated in the literature but that more research will be needed to permit any final conclusions. It seems likely that diffusion is one major contributor in fat migration, which will, in combination with re-crystallisation at the surface, cause bloom. The cracking phenomenon has not been studied to the same extent. Theories suggested all need further evaluation to permit any conclusions. Few studies have focused on the interface between filling and shell which experiences extensive structural changes during fat migration.

Many suggestions have been made on how to reduce fat migration and bloom, such as anti-bloom fat, stabilising fat and edible coatings, but this does not offer any solution to SME companies to produce bloom-and crack resisting pralines on a small production scale.

Healthy structuring

Structuring plant cell materials using pretreatment: The licentiate thesis by Evelina Tibäck at Chalmers University of Technology, titled “Structuring plant cell materials using pretreatment – Effects on texture and carotenoid accessibility” is based on three papers, accepted by or submitted to scientific journals:

1. Mechanical and thermal pretreatments of crushed tomatoes: Effects on consistency and in vitro accessibility of lycopene;
2. Processing of tomatoes: Impact on in vitro bio-accessibility of carotenes and textural properties; and
3. Thermal pre-treatments of carrot pieces using different heating techniques: Effect on quality related aspects.

The first paper concerned the effects of crushing intensity and heat treatments on lycopene content and in vitro accessibility.

In the second paper, the impact on in vitro bio-accessibility and retention of lycopene and beta-carotene as well as textural properties was investigated, after low and high temperature blanching and an additional boiling step after blanching.

The third paper concerned the effect of low and high temperature blanching in combination with Ca²⁺ soaking on the activity of peroxidase and pectinmethylesterase and structural properties and β-carotene content.

The overall objective was to understand how microstructure, texture and in vitro carotenoid accessibility are connected, and how these properties can be controlled by pre-processing operations.

Crushed tomatoes and carrot pieces are commonly used as ingredients in food products and were evaluated in this project, investigating the influence of pre-treatment by low and high temperature blanching, crushing intensity and the addition of calcium, adding also a boiling step to produce samples representative of ready-to-eat products. Textural properties of crushed tomatoes were evaluated by Bostwick consistency index and vane viscosity, and carrot texture by compression and tensile tests. Microstructure was studied by light-, confocal- and transmission electron microscopy. In crushed tomatoes, carotenoid content was determined by HPLC and carotenoid accessibility using a static in vitro digestion model.

Thermal pretreatment was seen to significantly affect crushed tomatoes and carrot pieces. Low temperature-long time (LTLT) blanching gave crushed tomatoes of low consistency (due to the activation of pectic enzymes) and firm carrot pieces after boiling.The hardness retention of the carrot pieces could be linked to observation of the microstructure, which showed a retention of the cell wall structure similar to that of raw carrots. A study of the microstructure of crushed tomatoes showed changes that suggested an effect on carotenoid accessibility. A combination of intense crushing and thermal treatment was needed to increase in vitro lycopene accessibility.

Important conclusions are that mechanical and thermal pre-treatments can be used to design tomato and carrot products with desired textural properties and to increase in vitro accessibility of lycopene in tomatoes.

The project has received financial support from the European Commission FOOD-2004-TS.4.1.3:iu Project 023115-Healthy structuring which is gratefully acknowledged.

Tasty berry dishes to increase consumption of healthy food: This project is part of the new development program at SIK. The aim of the project, which is now in progress in cooperation with four food companies, is to develop new dishes that are healthy, attractive and tasty in order to raise the consumption of these commodities.

Within this project, Elodie Prost from France will carry out her diploma work titled “Processing of bilberries – Impact on the concentration of anthocyanins in relation to textural properties”. Few studies have been reported on berries in terms of what happens to their health promoting substances during and after processing, focus having been on microbiological safety, taste and appearance more than on health aspects. Today, health aspects are becoming important, and the participating companies would like to know more of how present handling and processing methods affect health promoting substances in the berries.

The aim of the diploma work is to study the content of anthocyanins in bilberries and black currant, by UV spectroscopy after different heat treatments. Also, colour (Color Reader CR-10), consistency (Stress Tech) and microstructure (by light microscopy) will be analysed and related to the amount of retained anthocyanins. The development work will be in collaboration with experts in process technology and structure/texture and consumer and sensory analysis at SIK and expertise in health aspects at Chalmers University of Technology.

Spatial distribution of the naturally associated microflora of carrot, broccoli and tomatoes: This was a presentation at the Total Food conference at Norwich, UK, by E.J.Saggers (IFR), co-authored by J.M. Newman and C,Ohgren (IFR), M.Langton (SIK) and T.F. Brocklehurst (IFR). The aim of the study was to enumerate the numbers and types of bacteria associated with specific regions of broccoli, carrot and tomato to determine the spatial distribution of the naturally associated microflora and whether ingress into the tissues was responsible for this distribution.

The vegetables and fruit were aseptically dissected into component parts, and bacterial counts performed on each part. Organisms were found on all components of broccoli and carrot tissues in relatively high numbers and were predominantly Pseudomonas spp. Tomatoes, however, had very few naturally associated bacteria, predominantly located at the stalk end and were not Pseudomonas spp.

Bacteria were found in the inner tissues, and it was hypothesised that they were able to get access by penetrating through interstitial spaces. This was investigated using fluorescently tagged bacteria and confocal laser-scanning microscopy. Gfp⁺ Escherichia coli were inoculated onto the surface of carrot pieces and their progression into the tissue studied. The resulting images clearly show that Gfp⁺ E. coli and naturally fluorescent Pseudomonas spp. were able to penetrate into the inner component parts of the plant. The microbiological work was carried out by IFR and the CLSM work by SIK.

The work has received financial support from the European Commission FOOD-2004-TS.4.1.3:iu Project 023115-Healthy structuring which is gratefully acknowledged.

Aroma and sensory

Defining texture modified foods for dysphagic people: A seminar at SIK reported on “Consistency optimisation and sensory design for health and well-being of the elderly” to disseminate results from a project on specially designed foods for elderly suffering from chewing and swallowing disorders. It was apparent from work done and previous experience that nutritional treatment by texture modified food is needed for dysphagic persons to prevent malnutrition.

A new project was initiated to define and describe different modified textures and develop a system of objective, quantitative and well-defined guidelines for modified textures used to treat dysphagic persons. In the collaborative work, in which SIK, Malmoe University Hospital, Sahlgrenska Hospital and Findus AB were involved, a guide to classify and describe different texture modified consistencies had first been developed, based on previous experience. With this guide as a basis for the study and the choice of analysed products, a total of 15 products (2-3 products from five of the six guide categories of the guide) were analysed by sensory evaluation and rheological measurements. For the sensory work, quantitative descriptive analysis by an external trained analytic panel was used and the rheolgical measurements comprised shear viscosity and extensional viscosity for liquids and penetration and oscillatory tests for solids.

Six soups with different viscosities and nine solids (pâtés, jellied products, timbales and sherbert) were analysed at 8°C and/or 60°C. By the sensory analysis, the solid products were classified into three predefined groups. Pâtés were mostly differentiated from timbales and jellied products in chewing resistance and perceived particles. Timbales were perceived as more porous, wobbly, creamy and melting than pâtés. Jellied products had a lower degree of perceived chewing resistance and firmness but were more melting and creamy compared to the other categories. Rheological data indicated that solid products could be separate by their G´- values.

The liquids were classified into two predefined groups according to the sensory analysis, thickened and thin liquids. Results from the rheological measurements implied that the consistency index (K) could be used to distinguish between the two classes.

The textures described in the above-mentioned Swedish guide could be characterised objectively by a combination of sensory evaluation and rheology measurements. Correlation of data indicated that ease of swallowing was correlated with extensional viscosity. Firmness and chewing resistance were positively correlated with G', Young's modulus and maximum force. Melting, porosity, wobbling and creaminess were negatively correlated to G', Young's modulus and Max load.

It is concluded that a combination of methods is needed in the characterisation and classification of texture modified food for dysphagic patients.

Sustainable food production and environmental management

SIK presentations at the Total Food 2009 conference

At the conference, which took place on 22-24 April, three SIK papers related to sustainable food production were presented.

LCA for co-product exploitation: In his paper, Ulf Sonesson discussed the environmental implications when by-products or waste streams from food processing are exploited for more valuable products instead of just wasted. The need for waste management and emissions involved with this are reduced. At the same time, the new products produced from “waste” might replace existing market products to further decrease the total environmental impact. These complex interconnections should be considered when evaluating co-product exploitation.

Life Cycle Assessment is a methodology developed to quantify and evaluate the environmental impact of products and services. In the case of evaluating co-product exploitation a more limited LCA may be sufficient, the question being if we will do better or worse for the environment by implementing the new process.

It was concluded that, in order to make environmentally sound decisions when developing new exploitation processes for food-industry co-products, a holistic approach to evaluate the environmental effect is crucial. By using a method based on LCA one can achieve this.

Environmental assessment of novel processing technologies in the food industry: Jeniifer Davis, SIK, co-authored by Graham Moates and Keith Waldron, Institute of Food Research, Norwich, studied the environmental impact caused by the novel techniques of high pressure treatment at ambient and high temperature, ohmic heating and microwave heating, evaluated in the EU NovelQ project, in comparison with conventional heat processing for processing strawberry jam and tomato salsa. The goal of the study was to contribute to the development of environmentally sound food processing.

The study used factory visits and industry contacts along with recognised data base sources to collect appropriate data, from the cultivation stage through production, packaging, transport, distribution, retail, household storage and waste as well as disposal/recycling of the packaging. A commercially available LCA software package was used to try and quantify the overall environmental footprint of the product over a range of impact categories.

In terms of global warming potential and total energy use, the novel techniques had a lower environmental impact than the conventional ones. However, when examining the entire life cycle impact of the product, the choice of type and size of packaging was a more important factor.

Integrated evaluation of food process systems for improved efficiency and reduced environmental impact: This paper was presented by Karin Östergren, SIK, and co-authored by Johanna Berlin, Katarina Lorentzon and Barbro Sundström, SIK, and Björn Johansson, Chalmers University of Technology.

Changes in food production systems not only influence the environmental impact on site but also the food chain upstream and downstream, as well as the overall efficiency. Based on the concepts of lean production and environmental systems analysis, the impact of changes was evaluated in a plant for fermented dairy products, in a juice packaging plant and in a sausage production plant. Discrete event simulation was used, including conventional parameters for efficiency as well as environmental category indicators.

A simultaneous evaluation of production efficiency and the environmental impact in a life cycle perspective was found to be time efficient, and also exposed aspects that would most likely not have been exposed, had these two factors been considered separately.

For the juice packing plant, it was shown that the process related GWP global warming potential (GWP), could be reduced by one fifth by increasing the production frequency to facilitate taking care of product spillage originating from product changeovers.

For the dairy, it was possible to reduce the GWP by up to 50% by a combination of measures, including state of the art technology to reduce product spillage, increased production frequency of selected products and by changing the fuel and electricity mix being used.

For sausage production, reduction of spillage and electricity use was found to be the major issues to consider.

Among general conclusions are that the system boundaries greatly influence the results. Finally, key factors for successful application of “green process design” are to identify key indicators that promote overall efficiency and good communication between the production and the environmental units within the company.

SIK-presentation at the IAMA 19th Annual World Forum and

Symposium on Global challenges – Local solution in Budapest

Literature

Bülow,M., Ekberg,O., Ekman,S., Johansson,D., Rothenberg,E., Stading,M. and Wedin,K. Systematic and objective definitions of texture modified foods in nutritional treatments. SIK-Reort 787, 2009.

Ekman,S., Johansson,D., Stading,M. and Wedin,K. Systematic and objective definitions of texture modified foods in nutritional treatments. Presentation at the 8th Pangborn Sensory Science Symposium in Florence, Italy.

Hillerström,A., Skov Pedersen,J., Altskär,A., Langton,M., van Stam,J., Andersson,M. and Kronberg,B. Transparency and wettability of PVP/PDMS-IPN synthesized in different organic solvents. Submitted to Polymer Science.

Levenstam,E. Improvement of gluten free bread intended for storage in room temperature. Project report. Department of Chemical and Biological Engineering, Chalmers University of Technology. 2009.

Lorén,N., Nydén,M., Hermansson,A-M. Determination of local diffusion properties in heterogeneous biomaterials. Adv. Colloid Interface Sci (2009), doi:10.1016/j.cis.2009.05.004

Niemann,C., Langton,M., Alminger,M., Ahrné,L., Bialek,L., Larqué Daza,E., Brocklehurst,T., Hendrickx.M. and Waldron,K. High bioavailability of nutrients by “Healthy Structuring” of convenience foods. Submitted for publication in Trends in Food Science.

Oscarsson,H. The effective growth inhibition of Zygosaccharomyces bailii from bensoic acid and sorbic acid at different pH, temperature and sugar content.(In Swedish with English abstrac), Masters thesis, Sahlgrenska Academy, University of Gothenburg, 2009.

Tibäck,E. Structuring plant cell materials using pre-treatments. Effects on texture and carotenoid accessibility. Licentiate thesis, Chalmers University of Technology, 2009.

Wendin,K., Ekman,S., Bülow,M., Ekberg,O., Johansson,D., Rothenberg,E. and Stading,M. Objective and quantitative definitions of modified food textures for people suffering from dysphagia. Submitted for publication in an international journal.

New Nordic development

Superlight pitcher package for the aseptic market

The Swedish packaging company, Ecolean, has launched a new aseptic system for packaging milk and non-carbonated beverages. The package material for a one litre pack weighs only 14 g and is composed 2/3 of plastic materials and 1/3 of chalk, in 7-8 laminated layers. Smart construction and design makes the filled package stiff and easy to handle, and it functions as a standing pitcher on the table.

By folding, sealing and punching, flat package “blanks” are produced, which are sterilised by electron irradiation and sealed, leaving the machine as a roll of flat, sealed, empty and internally sterile packages, needing very little space for storage and distribution. In the novel filling machine, the “blanks” are sterilised by hydrogen peroxide and UV light, cut open, unfolded, filled and sealed under aseptic conditions. The system has attracted considerable interest also because of its environmental profile.

Next issue

The next issue of SIK Technology News is to be published in October 2009. Contact Bruno Hedlund if you would like further details of the above material or if you would like to order any of the reports; Tel: (+4631) 335 5600, fax (+4631) 833 782 or e-mail: bruno.hedlund@sik.se .

Professor Nils Bengtsson is IUFoST correspondent for Sweden and a consultant, and a former President of SIK – The Swedish Institute for Food and Biotechnology (Institutet för Livsmedel och Bioteknik AB), Box 5401, SE-40229 Göteborg, Sweden; E-mail: info@sik.se