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Simplified energy modeling to investigate the effect of lighting strategies on the energy efficiency of container indoor farms

Wittmann, S.; Jüttner, I.; Mempel, H. (2022)

DGG-Proceedings 2021/10, 2, S. 1-7.
DOI: 10.5288/dgg-pr-10-02-sw-2021


Open Access
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Predicting shelf life along horticultural supply chains: Evaluation of applicable quality parameters using near-infrared scanner

Huneck, L.; Kulko, R.; Wittmann, S.; Elser, B.; Mempel, H. (2022)

DGG Proceedings 2021/10, 5, S. 1-8.
DOI: 10.5288/dgg-pr-10-05-lh-2021


Open Access
 

Visible-Near-Infrared Scanners enable a noninvasive prediction of quality properties of fruit and vegetable based on previously created models. A combination of NIR scanners and
machine learning methods can lead to economic improvements and reduction of food waste by strategies like "first expired, first out" and dynamic pricing. In order to identify parameters
capable of showing dynamic postharvest development, three horticultural products with different postharvest behavior (e. g. strawberry, table grape and mango) were chosen for
morphological and statictical analysis. According to the results, a graduation of spectra in correspondence to the day of measurement was noticeable for strawberry regarding the a-
value as well as presumingly mass loss for both mango and table grape. Furthermore, a PLS model for the a-values r2cv = 0.80 was developed for strawberries.

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Controlled deficit irrigation – effects on growth and water relations of Daucus carota L. roots

Herppich, W.; Mempel, H.; Schreiner, M.; Huyskens-Keil, S. (2022)

Acta Horticulturae ISHS2022, 1335, S. 681-686.
DOI: https://doi/org/10.17660/ActaHortic.2022.1335.86

 

Regulated deficit irrigation (RDI) comprises controlled reduction of irrigation during certain phases of plant development, accepting minor yield reduction but maximising net returns. To optimise RDI, plant response-based irrigation scheduling may be essential. For this, the knowledge of plant reactions to soil water regimes is indispensable. In field trials (randomized block design, 3 repetitions), ‘Nanthya’ carrots (F1-hybrid) were grown at 20, 40, 60 and 80% field capacity (determined by TDR sensors), yielding soil water contents of 5.1±0.2, 6.2±0.8, 10.1±0.5 and 11.2±0.2% (controls). To guarantee constant controlled soil water contents, plastic rain shelter (76% transparency) were applied. Plots were irrigated if necessary. Treatments started 23 d after sowing (DAS), first sampling was 91 DAS, while final harvest was 106 DAS. On each date, fresh and dry mass, water content, water potential, osmotic potential, turgor and stiffness of carrot tubers were analyzed. Root fresh mass (n=20 carrots per treatment) was higher at high water availability only at the 1st sampling but not at the final harvest. Here, water regime did not affect yield. At this time, root tuber water potential was lower than at the 1st sampling and it was also lower at low soil water availability (20%, 40%). Similar results were obtained for the mean osmotic potential. These variations partially resulted from osmotic adjustment (at 1st harvest) and from a lower root tuber water content at the final sampling. The generally higher modulus of elasticity at this date indicated water volume-independent cell wall-stiffening, i.e. elastic adjustment. The presented results point out that moderately reduced (by 20%) irrigation of carrots does not affect their yield, while pronounced water shortage may induce physiological adjustment.

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Efficiency of the electric energy consumption of an indoor farm by focusing on optimized lighting strategies

Wittmann, S.; Jüttner, I.; Liedl, P.; Mempel, H. (2022)

Acta Horticulturae ISHS 2022, 1337, S. 73-79.
DOI: 10.17660/ActaHortic.2022.1335.86

 

Several lighting strategies in an indoor farm are compared regarding the annual electrical energy consumption. Based on measurements of the energy consumption during one experiment, conducted inside the indoor farm at the HSWT, an energy balancing model was calibrated and subsequently validated by a second experiment. The model was then used to calculate the potential reduction of the annual electrical energy consumption concerning several different lighting strategies. Furthermore, different settings of temperature set points and the impact of an optimized heat transfer coefficient as well as a more efficient performance for heating and cooling are considered. The measured and the modeled energy consumption and the values regained by the model showed a high regression coefficient (R2=0.936). The prediction of the energy consumption during the second experiment was also possible (R2=0.738) with a total difference to the measured consumption of 29.1 kWh. Regarding the given technical settings of the indoor farm, the annual electrical energy consumption can be reduced by up to 16% by an adjustment of the temperature strategy while reaching a similar yield. By assuming an optimized technical setting, the relevance of the lighting strategy increased significantly. Based upon this an annual reduction of the electrical energy consumption of up to 21% seemed conceivable.

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Framework for sustainability assessment of the value chain of flowering potted plants for the German market

Mempel, H. (2021)

Journal of Cleaner Production 329/2021, 129684 (329), S. 1-15.
DOI: 10.1016/j.jclepro.2021.129684


Open Access
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Framework for sustainability assessment of the value chain of flowering potted plants for the German market

Havardi-Burger, N.; Mempel, H.; Bitsch, V. (2021)

Journal of Cleaner Production 2021, 129684 (329), S. 1-15.
DOI: 10.1016/j.jclepro.2021.129684


Open Access
 

The value chain of flowering potted plants (FPP) is associated with environmental, social and economic sus-
tainability challenges. Indicator-based assessment methods can provide insights into sustainability performance
of agricultural value chains. The FPP value chain is not comparable to other agricultural systems and therefore
cannot be assessed with existing indicator-based tools. In this study, a framework was developed for sustain-
ability assessment of the FPP value chain, from breeding to distribution. The development of the framework
involved defining sustainability themes and subthemes based on the characterization of the value chain and the
investigation of social, environmental and economic sustainability challenges. The generic sustainability
assessment tools, Sustainability Assessment of Food and Agriculture Systems (SAFA) and Response-Inducing
Sustainability Evaluation (RISE), provided the foundation for indicator selection and development. The cur-
rent study emphasized the need for a system-specific view, especially in unique systems such as the FPP value
chain, because generic assessment tools, such as SAFA and RISE, do not cover all sustainability subthemes. Most
of the indicators missing from generic assessment tools were environmental indicators. Environmental assess-
ment is closely related to value chain stages and product-specific processes, therefore indicators were allocated
according to the value chain stages, breeding, production and distribution. Social sustainability themes are
influenced by national and regional socio-economic conditions, such as government provision of healthcare and a
social safety net. Therefore, indicators are allocated based on geographical regions and stakeholder groups. The
economic subthemes are determined by industry structure and sector-specific conditions. The ornamental sector
is characterized by low margins and high uncertainty, related to profitability and vulnerability. Despite the initial
evaluation performed in the current study, in the next step, industry actors need to determine the feasibility of
the indicators. The implementation of the framework developed in the current study will provide further insights
into the value chain, which will guide actors in taking actions for performance improvement and provide
guidance for policy-makers in setting sustainability targets.

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The potentials of indoor farming for plant production

Mempel, H.; Jüttner, I.; Wittmann, S. (2021)

Automatisierungstechnik 69 (4), S. 287-296.
DOI: 10.1515/auto-2020-0044

 

Plant production in indoor farming systems offers significant advantages compared to open field orgreenhouse production systems. Especially in terms of quality and the ability for automation the system is superior to the conventional production systems. Concerning resource consumption indoor farming has considerable advantages in regard to water consumption and the use of pesticides.The main disadvantage is the high consumption of electrical energy. Taking advantage of the specific benefits or eliminating the disadvantages, for example by using renewable energies, different potentials and fields of application for indoorfarming arise.The paper outlines the potentials and future fields of application of indoor farming considering the specific differences to conventional production systems related to resource consumption, quality and automation.

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Indoor Vertical Farming: konsequente Weiterentwicklung des geschützten Anbaus

Wittmann, S.; Jüttner, I.; Spence, M.; Mempel, H. (2021)

Jahrbuch Agrartechnik 2021 (Band 32), S. 1-15.
DOI: 10.24355/dbbs.084-202012111306-0

 


Climate change and increasing global urbanization accelerate the expansion of protected cultivation systems. However, certain dependences to external weather conditions remain even in modern greenhouses. Indoor vertical farming, on the other hand, pursues complete inde-pendence from external weather conditions with the aim for highly accurate control of all crop parameters. Particularly with regard to the advancing climate change and the need for sustainable resource consumption, there are clear advantages due to the year-round and independent cultivation of plants and raw materials under optimal conditions. The complexity in the optimal networking of the plant-technology systems offers intensive development opportunities for dig-itization and interdisciplinary collaboration.

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Food-scanner applications in the fruit and vegetable sector

Goisser, S.; Wittmann, S.; Mempel, H. (2021)

Landtechnik 76 (1), S. 52-67.
DOI: 10.15150/lt.2021.3264


Open Access
 

In the past few years, portable and smartphone-based diagnostic technologies have found their way into the agri-food industry. The aim of this research was to evaluate the perfor-mance of portable near-infrared (NIR) spectrometers, so called food-scanners, with regard to their predictive accuracy of important quality parameters of fruit and vegetables. Food-scan-ner measurements were performed in combination with destructive measurements of the corresponding quality trait (sugar content, dry matter, relative water content) on a wide range of produce from the fruit and vegetable assortment. This study evaluated dry matter content of apple, avocado, blueberry, table grape and tangerine, which yielded cross validation re-sults (r²) of up to 0.95, 0.87, 0.94, 0.92 and 0.92 respectively. Furthermore, the evaluation of food-scanner spectra for the prediction of sugar content of blueberry, kiwi, mango, persim-mon, table grape, tangerine and tomato yielded cross validations (r²) of up to 0.95, 0.84, 0.80, 0.75, 0.95, 0.93, and 0.87. Furthermore, relative water content of ginger obtained a cross val-idation correlation of r² = 0.91. The results show that these traits can be predicted with a high degree of accuracy using non-destructive measurements performed with three commercially available food-scanners SCiOTM, F-750 Produce Quality Meter, and H-100F. Consequently, food-scanners can be used as objective measurement tools along the supply chain of fresh produce to quickly determine fruit quality. In addition, a practical example shows the poten-tial of these instruments for non-destructive quality assessment in incoming goods control at fruit and vegetable wholesalers over a time period of several weeks. Furthermore, possible areas of application of food-scanners along the supply chain of fresh produce are discussed, possibilities for practical applications are presented and time-saving means are highlightedLANDTECHNIK 76(1), 2021, 52–67Food-scanner applications in the fruit and vegetable sectorSimon Goisser, Sabine Wittmann, Heike MempelIn the past few years, portable and smartphone-based diagnostic technologies have found their way into the agri-food industry. The aim of this research was to evaluate the perfor-mance of portable near-infrared (NIR) spectrometers, so called food-scanners, with regard to their predictive accuracy of important quality parameters of fruit and vegetables. Food-scan-ner measurements were performed in combination with destructive measurements of the corresponding quality trait (sugar content, dry matter, relative water content) on a wide range of produce from the fruit and vegetable assortment. This study evaluated dry matter content of apple, avocado, blueberry, table grape and tangerine, which yielded cross validation re-sults (r²) of up to 0.95, 0.87, 0.94, 0.92 and 0.92 respectively. Furthermore, the evaluation of food-scanner spectra for the prediction of sugar content of blueberry, kiwi, mango, persim-mon, table grape, tangerine and tomato yielded cross validations (r²) of up to 0.95, 0.84, 0.80, 0.75, 0.95, 0.93, and 0.87. Furthermore, relative water content of ginger obtained a cross val-idation correlation of r² = 0.91. The results show that these traits can be predicted with a high degree of accuracy using non-destructive measurements performed with three commercially available food-scanners SCiOTM, F-750 Produce Quality Meter, and H-100F. Consequently, food-scanners can be used as objective measurement tools along the supply chain of fresh produce to quickly determine fruit quality. In addition, a practical example shows the poten-tial of these instruments for non-destructive quality assessment in incoming goods control at fruit and vegetable wholesalers over a time period of several weeks. Furthermore, possible areas of application of food-scanners along the supply chain of fresh produce are discussed, possibilities for practical applications are presented and time-saving means are highlighted.

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Indoor Farming Marjoram Production—Quality, Resource Efficiency, and Potential of Application

Wittmann, S.; Jüttner, I.; Mempel, H. (2020)

Agronomy 10, 1769 (11).
DOI: 10.3390/agronomy10111769


Open Access
 

Indoor vertical farming offers great opportunities regarding a sustainable and consistent production of high-quality herbs and raw materials all year round for the perfume, chemical, or food industry. Cultivation takes place in an enclosed structure, operating predominantly independent from external conditions in multi-layer systems equipped with artificial lighting, enabling extremely high resource use efficiencies with a simultaneous increase in yield. On the other hand, field production in terms of plant quality and harvesting times is highly influenced by environmental conditions, making it difficult to maintain homogenous raw material qualities throughout the year. To show how different light qualities affect the overall efficiency and quality of Origanum majorana grown in an indoor farm, the resource consumption, yield, and cultivation time as well as the essential oil quantity was analyzed, and the efficiencies in terms of energy and land use efficiency calculated. The experimental setup clearly demonstrated that the yield regarding fresh as well as dry matter and oil content was comparable to one square meter of open field production. Based on this, the multi-layer system and the noticeable lowered growth period result in a significantly higher area efficiency compared to the open field, leading to a potential increase of annual yields of dried leave weight and oil contents by up to 21 times. It was also shown that a white spectrum (W) showed similar influence on plant growth and yield as a spectrum consisting of blue and red (B/R). Nevertheless, the LED treatment W did show higher light use efficiencies as well as a better working conditions inside the cultivation chamber. By an integration of indoor vertical farming into existing industrial processes, new and innovative opportunities for a flexible and low-risk supply chain seem feasible and according to German food industry meet the interests of existing stakeholders.

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Evaluating the practicability of commercial food-scanners for non-destructive quality assessment of tomato fruit

Goisser, S.; Fernandes, M.; Wittmann, S.; Ulrichs, C.; Mempel, H. (2020)

Journal of Applied Botany and Food Quality 2020 (93), S. 204-214.
DOI: 10.5073/JABFQ.2020.093.025


Open Access
 

The assessment of tomato fruit quality depends on a variety of extrinsic and intrinsic quality parameters such as color, firmness and sugar content. Conventional measurement methods of these quality parameters are time consuming, require various measurement devices, and in case of intrinsic quality, involve destructive measurements. Latest research focused on the non-destructive determination of these parameters by using spectroscopic measurements. The goal of this study was to evaluate the capability of three commercial-
ly available portable and miniaturized VIS/NIR spectrometers, so
called food-scanners, in predicting various tomato quality attributes in a non-destructive way. Additionally, this study evaluated the software provided by manufacturers for building of prediction models by comparing the results derived from those software tools to state-of-the-art software for multivariate analysis. Evaluation of food-scanner spectra resulted in prediction models of high accuracy (r² > 0.90) for tomato fruit firmness, dry matter, total soluble solids and color values L*, a* and h°. Prediction models computed with manufacturer’s software showed similar accuracy to those derived from state-of-the-art evaluation software. Results of this study illustrate the great potential of commercial food-scanners for non-destructive quality measurement. Further important features of food-scanners with respect to the application along the fresh produce supply chain are addressed.

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Indoor Vertical Farming – Ein innovatives System für die Pflanzenproduktion der Zukunft

Mempel, H. (2020)

Homepage: Stiftung Energie & Klimaschutz 2020.

 

Das Indoor Vertical Farming spezialisiert sich auf die Produktion von Pflanzen in mehrlagigen, vertikal angeordneten Kultursystemen in einer geschlossenen Gebäudestruktur (Container, Lagerhallen, etc.). Die Lichtenergie für das Pflanzenwachstum wird über künstliche Belichtungssysteme wie LED-Module zur Verfügung gestellt. Von der Temperatur über die Luftfeuchte, Belichtungszeit und -intensität, dem Lichtspektrum bis hin zur Bewässerung kann alles gezielt eingestellt und optimiert werden. Sensoren und Kamerasysteme ermöglichen zudem das Wachstum und die pflanzliche Entwicklung in Echtzeit zu beobachten und kontinuierlich zu optimieren.

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Driving forces and characteristics of the value chain of flowering potted plants for the German market

Havardi-Burger, N.; Mempel, H.; Bitsch, V. (2020)

European Journal of Horticultural Science 85 (4), S. 267-278.
DOI: 10.17660/eJHS.2020/85.4.8

 

The study investigated the value chain of flowering potted plants supplying the German market and the drivers influencing chain actors. The study builds on strategic and horticultural value chain literature. Data was collected by conducting 20 in-depth interviews with chain actors from different stages in the value chain and analyzed through qualitative content analysis. Results showed that the value chain of flowering potted plants is divided in two pathways due to distinct propagation methods, either generative (seeds) or vegetative (cuttings). Whereas propagation material is generally produced in southern countries, such as Africa and Central America, young plants and potted plants are cultivated within Europe. The paper identified driving forces such as retailer requirements, weather conditions, price pressure and innovations. Furthermore, the study provides an overview of chain activities and processes to help the sector anticipate developments, and support stakeholders in future decisions.

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Comparison of colorimeter and different portable food-scanners for non-destructive prediction of lycopene content in tomato fruit

Goisser, S.; Wittmann, S.; Fernandes, M.; Mempel, H.; Ulrichs, C. (2020)

Postharvest Biology and Technology 167, 111232, S. 1-8.
DOI: 10.1016/j.postharvbio.2020.111232

 

Lycopene, the red colored carotenoid in tomatoes, has various health benefits for humans due to its capability of scavenging free radicals. Traditionally, the quantification of lycopene requires an elaborate extraction process combined with HPLC analysis within the laboratory. Recent studies focused simpler methods for determining lycopene and utilized spectroscopic measurement methods. The aim of this study was to compare non-destructive methods for the prediction of lycopene by using color values from colorimeter measurements and Vis/NIR spectra recorded with three commercially available and portable Vis/NIR spectrometers, so called food-scanners. Tomatoes of five different ripening stages (green to red) as well as tomatoes stored up to 22 days after harvest were used for modeling. After measurement of color values and collection of Vis/NIR spectra the corresponding lycopene content was analyzed spectrophotometrically. Applying exponential regression models yielded very good prediction of lycopene for color values L*, a*, a*/b* and the tomato color index of 0.94, 0.90, 0.90 and 0.91, respectively. Color value b* was not a suitable predictor for lycopene content, whereas the (a*/b*)² value had the best linear fit of 0.87. In comparison to color measurements, the cross-validated prediction models developed for all three food-scanners had coefficients of determination (r²CV) ranging from 0.92 to 0.96. Food-scanners also can be used for additional measurements of internal fruit quality, and therefore have great potential for fruit quality assessment by measuring a multitude of important fruit traits in one single scan.

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Food-Scanners as a Radical Innovation in German Fresh Produce Supply Chains

Goisser, S.; Mempel, H.; Bitsch, V. (2020)

International Journal on Food System Dynamics 11 (2), S. 101-116.
DOI: 10.18461/ijfsd.v11i2.43


Open Access
 

Originally advertised as tools for end-consumers, portable food-scanners have recently reached a high level of awareness and show potential as instruments for quality assessment along fruit and vegetable supply c hains. The current study explores preferences and concerns of chain actors regarding the implementation of this technology through semi-structured interviews. Results indicate that food-scanners could facilitate quality control at different levels of the fresh produce supply chain by providing fast, non-destructive and objective measurements. Concerns about the application of food-scanners could be identified with respect to potential additional requirements of fruit wholesaler resulting in more pressure on producers. To further a goal-oriented and user-directed development of this new technology, future research should be directed at its impacts on perception of fruit quality along the chain as well as end-consumers’ readiness to use these devices in everyday life.

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Sustainability Challenges and Innovations in the Value Chain of Flowering Potted Plants for the German Market

Havardi-Burger, N.; Mempel, H.; Bitsch, V. (2020)

Sustainability 12, 1905 (5).
DOI: 10.3390/su12051905


Open Access
 

This study investigated the sustainability challenges and the adoption of sustainability innovations along the value chain of flowering potted plants supplying the German market. Data was collected through eighteen in-depths interviews with chain actors from different stages of the value chain and analyzed through qualitative content analysis. The material flow of the value chain begins at the breeding level followed by the propagation level. Cuttings are produced mostly in African countries, rooted cuttings and potted plants are cultivated in Europe. The main environmental challenges include water scarcity, pesticide use and carbon footprint. Social challenges in Africa include low wages and difficult working conditions. In Germany, social challenges include recruitment and retention of employees and product transparency. Economic challenges include profitability and the need to comply with standards. Sustainability driven innovations can address some sustainability challenges. However, their implementation often leads to increased costs, financial risk and complexity of implementation. Furthermore, the lack of product transparency prevents the transfer of sustainability costs to the consumer by offering a sustainable product for a premium price. Business-to-business standards have generally had a positive influence on the adoption of sustainability innovations. But by setting certification as an entry barrier for suppliers, retailers have become more powerful chain actors.

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Potential and use of artificial lighting in horticulture

Mempel, H.; Wittmann, S. (2019)

Light and Engineering 27, S. 31-41.

 

The use of supplemental lighting in horticulture is continuously increasing. Compared to HPS luminaires LED have significant advantages like the possibility of a targeted compilation of the spectrum, the use of dimmable and dynamic adaptable luminaires, the insensitivity to the switching frequency, less heat radiation and the and the high energy efficiency. Experiments with monochromatic lighting show potentials for influencing various quality factors with specialized light spectra in order to reach the targeted plant quality. However, many questions are still open, resulting in a rather low transfer rate of specific lighting strategies in the applied horticulture. Beneficial effects of interlighting were shown in greenhouse experiments and their potentials discussed. In the future higher requirements on plant and fruit quality and a sustainable use of resources will result in a greater importance for specialized lighting strategies and advanced technological solutions.


Die Senkrechtpflanzer

Wolf, J.; Mempel, H. (2019)

Zeitungsartikel: Die Zeit, von Justin Wolff 2019 (45).

 

Ackerfläche wird knapp, doch Salat lässt sich gestapelt in Schränken und Regalen züchten. Ist die Technologie schon reif für die Produktion in großen Mengen? 

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Mobile Nahinfrarottechnik im Post-Harvest-Management

Goisser, S.; Mempel, H. (2019)

Vortrag im Forum "Auf einer Wellenlänge" des Forschungsprojekts "Food-Scanner" am 26.10.2019 in Freising.


Potential Application of Food-Scanners in Fruit and Vegetable Supply Chains and Possible Consequences for the German Market

Goisser, S.; Mempel, H.; Bitsch, V. (2019)

Proceedings in System Dynamics and Innovation in Food Networks 2019, S. 173-181.
DOI: 10.18461/pfsd.2019.1917


Open Access
 

Originally advertised as tools for end-consumers, food-scanners have recently gained publicity and show potential as instruments for quality assessment along the fruit and vegetable supply chain. The current study explores preferences and concerns of chain actors regarding the implementation of this technology through semi-structured interviews. Results indicate that food-scanners could facilitate quality control at different levels of the fresh produce supply chain by providing fast, non-destructive and objective measurements. Concerns about the application of food-scanners could be identified with respect to potential additional requirements of trading companies resulting in more pressure on producers. The use of food-scanners by end-consumers is discussed critically. To further a goal-oriented and user-directed development of this new technology, future research should be directed at its impacts on perception of fruit quality along the chain as well as end-consumers’ readiness to use these devices in everyday life.

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Prof. Dr. Heike Susanne Mempel


Hochschule Weihenstephan-Triesdorf

Institut für Gartenbau

T +49 8161 71-5853
heike.mempel[at]hswt.de