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  • 1. Al-Naamani, Laila
    et al.
    Dobretsov, Sergey
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Chitosan-zinc oxide nanoparticle composite coating for active food packaging applications2016In: Innovative Food Science & Emerging Technologies, ISSN 1466-8564, E-ISSN 1878-5522, Vol. 38, p. 231-237Article in journal (Refereed)
    Abstract [en]

    In this study antimicrobial properties of chitosan and chitosan-zinc oxide (ZnO) nanocomposite coatings on PE films were studied. Oxygen plasma pretreatment of PE films led to increased adhesion by 2% of chitosan and the nanocomposite coating solutions to the packaging films. Scanning Electron Microscopy (SEM) revealed uniform coatings on PE surfaces. Incorporation of ZnO nanoparticles into the chitosan matrix resulted in 42% increase in solubility; swelling decreased by 80% while the water contact angle (WCA) increased from 60 to 95 compared to chitosan coating. PE coated with chitosan-ZnO nanocomposite films completely inactivated and prevented the growth of food pathogens, while chitosan-coated films showed only 10-fold decline in the viable cell counts of Salmonella enterica, Escherichia coli and Staphylococcus aureus after 24-h incubation compared to the control. Industrial relevance: One of the greatest challenges of food industry is microbial contamination. The present study suggests that PE coating with chitosan-ZnO nanocomposite is a promising technique to enhance antimicrobial properties of the films. Chitosan-ZnO nanocomposite coatings improved antibacterial properties of PE by inactivating about 99.9% of viable pathogenic bacteria. Hence, our results show the effectiveness of the nanocomposite coating in the development of active food packaging in order to prolong the shelf life of food products.

  • 2.
    Björn, Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    A circular production of fish and vegetables in Guatemala: An in-depth analysis of the nitrogen cycle in the Maya Chay aquaponic systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study was done with the aim of deepening the understanding of the Maya Chay aquaponic systems. To meet the aim, a literature study on aquaponics, with an emphasis on the nitrogen metabolism in such systems, was conducted. Furthermore, a deep investigation of the specific Maya Chay systems was made to understand how these systems might be different from the general aquaponic designs. Finally, two nitrogen balances were developed with the purpose of examining the dynamics of the nitrogen transformations in two Maya Chay aquaponic systems. The measurements for the nitrogen balances was made between Mars 2017 to July 2017, and the model for the nitrogen balances evaluated the amount of nitrogen as:

    i) nitrogen input to the system through the feed,

    ii) nitrogen assimilated by the fish and the plants,

    iii) nitrogen accumulated in the sludge, and

    iv) nitrogen lost to the atmosphere through denitrification and similar processes such as anammox.

    The resulting nitrogen balances showed some interesting differences in the dynamics of nitrogen distribution. In the smaller Maya Chay XS system in Antigua, only 36 % of the nitrogen input was assimilated by the fish (30 %) and the plants (6 %) and 64 % of the nitrogen input could be regarded as lost, either to the atmosphere (46 %) or in the sludge (18 %). The other nitrogen balance showed that the distribution of nitrogen in the Maya Chay S system in Chinautla is much more efficient in taking care of the nitrogen input. In this system 70 % was assimilated by the fish (33 %) and the vegetables (37 %) and the remaining 30 % was lost, either to the atmosphere (14 %) or in the sludge (16 %).

    The nitrogen balances also showed that both systems are almost equally efficient in terms of nitrogen assimilation by the fish, and that the big differences lie in the rate of nitrogen assimilation by the plants (6 % vs. 30 %) and in the nitrogen loss to the atmosphere (46 % vs. 14 %). A likely explanation for these differences is the difference in design of the vegetable beds, where the less efficient system in Antigua has a large surface area for the vegetable bed, but only a small portion of this could be utilized for vegetable growth. Furthermore, a consequence of the larger surface is a larger anoxic zone in the bottom of the vegetable bed, which promotes the growth of denitrifying and anammox bacteria. These kinds of bacteria convert the dissolved ammonia, nitrite and nitrate to gas forms of nitrogen, such as nitrogen gas and nitrous oxide and thus nitrogen is lost from the system to the atmosphere.

    Finally, this study also showed a great difference in the ratio of vegetable to fish production between the systems, where the ratio was 0.43 in Antigua and 2.7 in Chinautla. This ratio further indicates the difference in design between the systems, especially regarding the vegetable beds, has an impact on how well they perform, both in terms in economic and productivity terms, but also in terms of the release of greenhouse gases (nitrous oxide). It can therefore be concluded that the original design of the Maya Chay system (i.e. the Chinautla system) is the preferable one.

    Even though the accuracy of the measurements in the experiments could be improved for future studies, this study has demonstrated the value of making nitrogen balances for aquaponic systems. Nitrogen balances increase the knowledge of the performance of the system and they increase the understanding of the dynamics of nitrogen transformations that takes place in the system. This knowledge can then be utilized to adjust the design and/or verify if either the aquaculture or hydroponic system is properly designed.

  • 3.
    Fallgren, Karl
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation. KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Sundborg, Håkan
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation. KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Future grocery: A study of the e-commerce grocery basket business in Sweden 2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The era of the Internet has become increasingly important in our daily life. Internet channels are rapidly growing into sophisticated businesses. This thesis purpose is therefore to conduct an initial study on a newly approaching e-commerce business, namely the grocery basket business. As there has not yet been much research in this field the overall aim is to contribute to the research in this business area. There are many who argue that in relation to the Internet and e-commerce fields there are two other important fields: business model and supply chain.

    A qualitative approach is used, based on triangulation methodology including a multiple case study and a survey. The cases are two different types of e-commerce companies: brick-and-clicks and pure-players. An empirical investigation covering twenty interviews and a questionnaire with one thousand respondents has been conducted.

    Findings supported by the interviews and the questionnaire reveal much knowledge about the grocery basket business. This are analyzed in relation to literature of business model and supply chain and according to the two cases of companies in the business.

    The study concludes that there is a great deal of challenges facing the grocery basket business in both fields of business model and supply chain. In both cases it is a challenge to retain customers, flexibility for customers, competition and supply chain development. Regarding brick-and-clicks a major challenge is to make their physical channel and online channel work together. Regarding pure-players a major challenge is their dependency of wholesalers. In addition, recommendations to these acknowledged challenges are benchmarking on other successful grocery companies and/or other successful e-commerce companies. Additional recommendation for pure-players is that they should cooperate with a brick-and-mortar company. Finally, the study shows some decent potential in the business to reduce emissions. This by providing eco-friendly products with pre planned recipes to fit with the products, and having fewer products in stock.

  • 4.
    Hägg, Göran M.
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Vogel, Kjerstin
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Karltun, Johan
    McGorry, R.W.
    Liberty Mutual Research Institute for Safety, Hopkinton, Mass., USA.
    How do different temperatures affect knife force?2015In: Ergonomics Open Journal, ISSN 1875-9343, E-ISSN 1875-9343, no 8, p. 27-31Article in journal (Refereed)
    Abstract [en]

    Meat cutters have long since claimed that knife forces increase with lower meat temperatures. This study was performed to find out what effects the meat temperature has on cutting forces. In addition, the same issue was addressed for pure fat. One hundred and forty four samples of lean meat and of fat respectively were collected and put overnight inone of three refrigerators with temperatures 2, 7 and 12°C, 48 in each. These samples were cut while measuring cutting forces in an Anago KST Sharpness Analyzer machine. The results show that there were no significant differences in knife forces concerning lean meat at the three temperatures. However, the force in pure fat at 2°C was significantly increased by 30% compared to the other temperatures. The forces in fat were generally three times higher than for lean meat, regardlessof temperature.

  • 5.
    Lindborg, PerMagnus
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics. Nanyang Technological University, Singapore.
    A taxonomy of sound sources in restaurantsIn: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910XArticle in journal (Refereed)
    Abstract [en]

    Restaurants are complex environments where all our senses are engaged. Physical and psychoacoustic factors have been shown to be associated with perceived environmental quality in restaurants. More or less designable sound sources such as background music, voices, and kitchen noises are believed to be important in relation to the overall perception of the soundscape. Previous research publications have suggested typologies and other structured descriptions of sound sources for some environmental contexts, such as urban parks and offices, but there is no detailed account that is relevant to restaurants. While existing classification schemes might be extendable, an empirical approach was taken in the present work. We collected on-site data in 40 restaurants (n = 393), including perceptual ratings, free-form annotations of characteristic sounds and whether they were liked or not, and free-form descriptive words for the environment as a whole. The annotations were subjected to analysis using a cladistic approach and yielded a multi-level taxonomy of perceived sound sources in restaurants. Ten different classification taxa were evaluated by comparing the respondents' Liking of sound sources, by categories defined in the taxonomy, and their Pleasantness rating of the environment as a whole. Correlation analysis revealed that a four-level clade was efficient and outperformed alternatives. Internal validation of the Pleasantness construct was made through separate ratings (n = 7) of on-site free-form descriptions of the environment. External validation was made with ratings from a separate listening experiment (n = 48). The two validations demonstrated that the four-level Sound Sources in Restaurants (SSR) clade had good construct validity and external robustness. Analysis  of the data revealed two findings. Voice-related characteristic sounds including a ‘people’ specifier were more liked than those without such a specifier (d = 0.14 SD), possibly due to an emotional crossmodal association mechanism. Liking of characteristic sounds differed between the first and last annotations that the respondents had made (d = 0.21 SD), which might be due to an initially positive bias being countered by exposure to a task inducing a mode of critical listening. We believe that the SSR taxonomy will be useful for field research and simulation design. The empirical findings might inform theory, specifically research charting the perception of sound sources in multimodal environments.

  • 6.
    Mazinanian, Neda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Comparison of the influence of citric acid and acetic acid as simulant for acidic food on the release of alloy constituents from stainless steel AISI 2012015In: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 145, p. 51-63Article in journal (Refereed)
    Abstract [en]

    To ensure the safety of metals and alloys intended for food contact, a new European test protocol (CoE protocol) using citric acid as a food simulant was published in 2013. This study investigated the influence of citric acid and exposure conditions on the metal release from an austenitic manganese stainless steel (AISI 201). Exposures in 5 g/L citric acid resulted in significantly lower metal releases compared with specific release limits set by the CoE protocol. 5 g/L (0.3 vol%) citric acid was more aggressive than 3 vol% acetic acid (Italian protocol) due to higher metal complexation. Studies on abraded surfaces revealed that most metals were released during the first 0.5 h of exposure due to surface passivation. Surface abrasion, increased temperature (40-100 degrees C), increased surface area to solution volume ratio (0.25-2 cm(2)/mL) and increased citric acid concentration (0-21 g/L) all resulted in increased released metal quantities.

  • 7. Simsek, Sebnem
    et al.
    Sanchez-Rivera, Laura
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab. Inst Invest Ciencias Alimentac, Spain.
    Nehir, El Sedef
    Karakaya, Sibel
    Recio, Isidra
    Characterisation of in vitro gastrointestinal digests from low fat caprine kefir enriched with inulin2017In: International Dairy Journal, ISSN 0958-6946, E-ISSN 1879-0143, Vol. 75, p. 68-74Article in journal (Refereed)
    Abstract [en]

    In vitro gastrointestinal digests from low fat caprines' milk kefir were characterised. The impact of the addition of different types of inulin (native, short-chain and long-chain) as a fat replacer on the subsequent release of peptides during digestion was also studied. A total of 52 peptides were identified, mainly from b-casein, following digestion. The gastrointestinal digests possessed angiotensin-converting enzyme (ACE)-inhibitory activity with IC50 values ranging from 190.71 +/- 2.91 to 364.68 +/- 31.27 mu g protein mL(-1). Among the identified peptides, four of them have been previously described as ACEinhibitors (LHLPLP, HLPLP, DKIHP, MAIPPK), and the presence of these sequences can explain the moderate ACE-inhibitory activity found in the samples. Rheological analysis revealed that all manufactured kefirs exhibited shear-thinning behaviour. No significant effect of viscosity on protein degradation during simulated gastrointestinal digestion was found under the working conditions.

  • 8.
    Thomsson, Olof
    et al.
    Biodynamic Research Institute, Järna, Sweden.
    Wallgren, Christine
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies.
    Global warming and fossil energy use2005In: Ekologiskt Lantbruk, ISSN 1102-6758, Vol. 46, p. 71-93Article in journal (Other academic)
  • 9.
    Wallgren, Christine
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies.
    Food in the Future: energy and transport in the food system2008Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis explores possible future forms of a sustainable food supply system from an energy aspect. Particular attention is devoted to local food supply as a means to reduce energy use for transport. The thesis consists of a covering essay and three studies: one futures study of the entire food supply system and two case studies of local farming.

    The results from the three studies had somewhat different characters, but provided suggestions on how the food system could be more energy-efficient. The futures study, which was on a more comprehensive level than the two case studies, included a full account of energy use for the food supply system in Sweden for the year 2000 and an exploration of future sustainable energy use in the shape of an image of the future. The two case studies provided indications on the potential for reduction in energy use for transport through local food supply in the future.

    The futures study explored the possibilities of reducing the energy use for food to a level that would be sustainable with regard to energy use. This meant generating an image of the future where energy use for eating was 60% lower in 2050 than in 2000. Sweden was used as the case and all data regarding energy use were for Swedish conditions. The existing possibilities to reduce energy used in the food supply system for producing, transporting, storing, cooking and eating food were explored and described in terms of a number of distinct, consecutively numbered ‘Changes’. These changes were presented in both a quantitative and qualitative way but should not be regarded as forecasts. Instead, they provide an illustration of the kinds of changes needed in order to achieve sustainable energy use in the food system.

    The outcome from the two case studies was that energy use for local food distribution was not obviously lower than that for conventional food transport. This may be surprising to many, since it is generally argued in the public debate that local food supply is a powerful means to reduce energy use in the food system. From an energy point of view, it could be more relevant to use a parameter based on the energy use per quantity of food instead of transport distance. An appropriate approach would therefore be energy-efficient food supply instead of local food supply. This would allow concerned consumers to make appropriate choices when purchasing food.

  • 10.
    Wallgren, Christine
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies.
    Local or global food markets: a comparison of energy use for transport2006In: Local Environment: the International Journal of Justice and Sustainability, ISSN 1354-9839, E-ISSN 1469-6711, Vol. 11, no 2, p. 233-251Article in journal (Refereed)
    Abstract [en]

    This study compares energy use for food transport to a farmers' market in Sweden with energy use for transport in the conventional food system. The farmers' market was investigated through data sampling from on-site investigations. The conventional food system was studied with the aid of life cycle assessments reported in the literature. Overall, the study found no significant differences in levels of energy use for transport to the farmers' market compared with the conventional food system. For certain products, such as fresh fruits and vegetables, transport-related energy use was much lower in the local system although the season in Sweden for this kind of product is restricted to two or three months at the end of the summer. However, there is considerable potential to increase energy efficiency in local food systems by organizing the selling in new ways and by using more energy efficient vehicles.

  • 11.
    Wallgren, Christine
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies.
    Höjer, Mattias
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies.
    Eating energy: Identifying possibilities for reduced energy use in the future food supply system2009In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 37, no 12, p. 5803-5813Article in journal (Refereed)
    Abstract [en]

    This paper explores the possibilities for reducing future energy use for eating to a sustainable level. A backcasting approach is used to generate an image of the future where energy use for eating is 60% lower in 2050 than in 2000. The currently known potential to reduce energy use in the food supply system for producing, transporting, storing, cooking and eating food is explored and described in terms of a number of distinct changes that are numbered consecutively and presented in both a quantitative and qualitative way. Sweden is used as the case and all data regarding energy use apply for Swedish conditions. An exercise like this illustrates the possible outcome of taking sustainability seriously. If sustainability is to be achieved, some images of the future are needed so that potential targets can be identified. This paper does not present forecasts, but illustrates the kind of changes needed in order to achieve sustainable energy use in the food system.

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