Effect of Cereal α-Amylase/Trypsin Inhibitors on Developmental Characteristics and Abundance of Digestive Enzymes of Mealworm Larvae (Tenebrio molitor L.)

The objective of this work was to investigate the potential effect of cereal α-amylase/trypsin inhibitors (ATIs) on growth parameters and selective digestive enzymes of Tenebrio molitor L. larvae. The approach consisted of feeding the larvae with wheat, sorghum and rice meals containing different levels and composition of α-amylase/trypsin inhibitors. The developmental and biochemical characteristics of the larvae were assessed over feeding periods of 5 h, 5 days and 10 days, and the relative abundance of α-amylase and selected proteases in larvae were determined using liquid chromatography tandem mass spectrometry. Overall, weight gains ranged from 21% to 42% after five days of feeding. The larval death rate significantly increased in all groups after 10 days of feeding (p < 0.05), whereas the pupation rate was about 25% among larvae fed with rice (Oryza sativa L.) and Siyazan/Esperya wheat meals, and only 8% and 14% among those fed with Damougari and S35 sorghum meals. As determined using the Lowry method, the protein contents of the sodium phosphate extracts ranged from 7.80 ± 0.09 to 9.42 ± 0.19 mg/mL and those of the ammonium bicarbonate/urea reached 19.78 ± 0.16 to 37.47 ± 1.38 mg/mL. The total protein contents of the larvae according to the Kjeldahl method ranged from 44.0 and 49.9 g/100 g. The relative abundance of α-amylase, CLIP domain-containing serine protease, modular serine protease zymogen and C1 family cathepsin significantly decreased in the larvae, whereas dipeptidylpeptidase I and chymotrypsin increased within the first hours after feeding (p < 0.05). Trypsin content was found to be constant independently of time or feed material. Finally, based on the results we obtained, it was difficult to substantively draw conclusions on the likely effects of meal ATI composition on larval developmental characteristics, but their effects on the digestive enzyme expression remain relevant

Plasma applications for the treatment of bean sprouts : safety, quality and nutritional assessments under aqueous and gaseous set-ups

Sprouts are particularly prone to microbial contamination due to their high nutrient content and the warm temperatures and humid conditions needed for their production. Therefore, disinfection is a crucial step in food processing as a means of preventing the transmission of bacterial, parasitic and viral pathogens. In this study, a dielectric coplanar surface barrier discharge (DCSBD) system was used for the application of cold atmospheric plasma (CAP), plasma activated water (PAW) and their combination on mung bean seeds. Overall, it was found that the combined seed treatment with direct air CAP (350 W) and air PAW had no negative impact on mung bean seed germination and growth, nor the concentration of secondary metabolites within the sprouts. These treatments also reduced the total microbial population in sprouts by 2.5 log CFU/g. This research reports for first time that aside from the stimulatory effect of plasma discharge on seed surface disinfection, sustained plasma treatment through irrigation of treated seeds with PAW can significantly enhance seedling growth. The positive outcome and further applications of different forms, of plasma i.e., gaseous and aqueous, in the agro-food industry is further supported by this research.peer-reviewe

Aqueous and gaseous plasma applications for the treatment of mung bean seeds

Sprouts are particularly prone to microbial contamination due to their high nutrient content and the warm temperatures and humid conditions needed for their production. Therefore, disinfection is a crucial step in food processing as a means of preventing the transmission of bacterial, parasitic and viral pathogens. In this study, a dielectric coplanar surface barrier discharge (DCSBD) system was used for the application of cold atmospheric plasma (CAP), plasma activated water (PAW) and their combination on mung bean seeds. Germination assessments were performed in a test tube set-up flled with glass beads and the produced irrigation water. Overall, it was found that the combined seed treatment with direct air CAP (350W) and air PAW had no negative impact on mung bean seed germination and growth, nor the concentration of secondary metabolites within the sprouts. These treatments also reduced the total microbial population in sprouts by 2.5 log CFU/g. This research reports for frst time that aside from the stimulatory efect of plasma discharge on seed surface disinfection, sustained plasma treatment through irrigation of treated seeds with PAW can signifcantly enhance seedling growth. The positive outcome and further applications of diferent forms, of plasma i.e., gaseous and aqueous, in the agro-food industry is further supported by this research.peer-reviewe

Plasma applications for the treatment of bean sprouts : safety, quality and nutritional assessments under aqueous and gaseous set-ups

Sprouts are particularly prone to microbial contamination due to their high nutrient content and the warm temperatures and humid conditions needed for their production. Therefore, disinfection is a crucial step in food processing as a means of preventing the transmission of bacterial, parasitic and viral pathogens. In this study, a dielectric coplanar surface barrier discharge (DCSBD) system was used for the application of cold atmospheric plasma (CAP), plasma activated water (PAW) and their combination on mung bean seeds. Overall, it was found that the combined seed treatment with direct air CAP (350 W) and air PAW had no negative impact on mung bean seed germination and growth, nor the concentration of secondary metabolites within the sprouts. These treatments also reduced the total microbial population in sprouts by 2.5 log CFU/g. This research reports for first time that aside from the stimulatory effect of plasma discharge on seed surface disinfection, sustained plasma treatment through irrigation of treated seeds with PAW can significantly enhance seedling growth. The positive outcome and further applications of different forms, of plasma i.e., gaseous and aqueous, in the agro-food industry is further supported by this research.peer-reviewe

Behandlung von Lebensmittelmatricen mit kaltem Atmosphärendruckplasma : gezielte Modifikation von Produkteigenschaften entlang der Wertschöpfungskette pflanzlicher und tierischer Produkte

The application of cold atmospheric pressure plasma (CAPP) was suggested as an innovative nonthermal technology for inactivating undesirable microorganisms on the surface of heat-sensitive food products. Moreover, CAPP may offer a promising approach for the tailored modification of product properties along value-added chains of plant and animal related products. Therefore, this thesis puts emphasis on providing evidence for the possible utilization of plasma-induced surface and ingredient interactions as a tool for the selective modification of secondary metabolite profiles in plants and techno-functionality of flours and proteins from peas. Further, the knowledge gained on plasma assisted modification of plant-based materials was transferred to animal-based materials from edible insects taking additionally into account microbial decontamination as another key issue in insect processing. The thesis imparts the detailed characterization of selected raw materials, the identification of proper CAPP setups and corresponding product-specific process parameters by performing process accompanying monitoring of plasma characteristics required to achieve desired modifications. Detailed investigations of the plasma-induced effects were conducted following a top-down approach by using suitable analytical methods providing insights into possible underlying mechanisms from macroscopic to molecular level. The macroscopic level of analysis included quality (color/texture), compositional (protein/fat/dry matter contents) and microbial (surface/overall total viable counts) methods, followed by determining techno-functional (water/fat binding/emulsification) and protein (solubility/water/fat binding/emulsification) properties, as well as protein structure (surface hydrophobicity/fluorescence properties/CD spectroscopy) on the microscopic and structural level, down to analysis of the protein composition (SDS-PAGE/tryptophan content/amino acid composition) on the molecular level. The results provide a scientific basis regarding the targeted use of the CAPP technology for functionalization and modification of high-protein food components and could therefore contribute to the bio-economic and resource efficient production of dry high-value protein products, as protein functionality plays a key role in improving existing products, developing new products, and utilizing alternative protein sources as new ingredients. Consequently, feedback on the applicability of CAPP for tested raw materials was derived by evaluating the effectiveness of the treatment regarding the desired process goal, and by identifying product-specific characteristics allowing transferability of the CAPP process with the long-term goal of combining plasma treatments with existing unit operations in established product-specific process lines. Initial approaches regarding the CAPP treatment of complex food matrices by using a plasma device, which is promising for the application in industrial scale, aimed at the development of innovative process combinations with focus on “plasma-drying” as a prospective future unit operation, which may contribute to reducing the expected costs of CAPP treatments. The potential of CAPP processing to become a routine tool for the food industry in the coming years is also reflected throughout all parts of this work, and thus, it provides a substantial contribution to promoting the successful admission of the CAPP technology in the food sector.Kalte Atmosphärendruckplasmen (KADP) gelten als innovative nichtthermische Technologien zur Inaktivierung unerwünschter Mikroorganismen auf Oberflächen hitzeempfindlicher Lebensmittel. Darüber hinaus bietet die KADP-Technologie ein vielversprechendes Konzept zur gezielten Modifikation von Produkteigenschaften entlang Wertschöpfungsketten pflanzlicher und tierischer Produkte. Die vorliegende Arbeit untersucht schwerpunktmäßig den möglichen Einsatz plasma-induzierter Oberflächen- und Inhaltsstoffinteraktionen zur selektiven und gezielten Modifikation von Sekundärmetabolitprofilen in Erbsenpflanzen und technofunktionellen Eigenschaften von Erbsenmehlen und –proteinen. Weiterhin wurden die über die plasma-gestützte Modifikation pflanzlichen Materials gewonnenen Erkenntnisse übertragen auf tierische Rohstoffe aus essbaren Insekten und zusätzlich die mikrobielle Dekontamination, als ein weiterer Schwerpunkt bei der Insektenverarbeitung, mit einbezogen. Die Arbeiten zur Erzeugung gewünschter Modifikationen umfassen die detaillierte Charakterisierung ausgewählter Rohstoffe, die Auswahl geeigneter KADP-Anlagen und korrespondierender produktspezifischer Prozessparameter, sowie die prozessbegleitende Erfassung notwendiger Plasmaeigenschaften. Die hierzu notwendigen detaillierten Untersuchungen der plasma-induzierten Effekte wurden nach einem Top-down- Ansatz unter der Nutzung geeigneter analytischer Methoden, die Einblicke in mögliche zugrundeliegende Mechanismen liefern, von der makroskopischen zum molekularen Ebene durchgeführt. Das makroskopische Untersuchungslevel beinhaltete Methoden zur Erfassung der Qualität (Farbe/Textur), Zusammensetzung (Protein-/Fett-/Trockensubstanzgehalt) und Mikrobiologie (Oberflächen-/Gesamtkeimzahl), begleitet von Untersuchungen technofunktioneller (Wasser-/Fettbinde-/ Emulgiereigenschaften) und Proteineigenschaften (Löslichkeit, Wasser-/Fettbinde-/Emulgiereigenschaften) als auch der Proteinstruktur (Öberflächenhydrophobizität/Fluoreszenzeigenschaften/CD-Spektroskopie) auf der mikroskopischen und struktureller Ebene, bis hin zur Proteinzusammensetzung (SDSPAGE/ Tryptophangehalt/Aminosäurezusammensetzung) auf der molekularen Ebene. Die Ergebnisse liefern eine wissenschaftliche Grundlage zur gezielten Nutzung der KADP-Technologie zur Funktionalisierung und Modifizierung proteinreicher Lebensmittelkomponenten und könnten folglich zur bioökonomischen und ressourceneffizienten Produktion hochwertiger trockener Proteinprodukte beitragen, da Proteinfunktionalität eine wesentliche Rolle in Produktverbesserung und -entwicklung und der Nutzung alternativer Proteinquellen spielt. Aus der Identifizierung produktspezifischer Eigenschaften und der Beurteilung der Behandlungseffektivität hinsichtlich des gewünschten Prozessziels wurden wichtige Erkenntnisse zum langfristigen Ziel der Kombination von KADP mit Prozessschritten etablierter Verarbeitungsketten gewonnen. Erste Versuche zur Behandlung komplexer Lebensmittelmatrices unter Nutzung einer Plasmaanlage, die sich zum Einsatz im industriellen Maßstab eignen würde, zielten auf die Entwicklung innovativer kosteneffizienter Kombinationen aus Plasma- und Trocknungsverfahren ab. Das Potential des KADP-Verfahrens in Zukunft zu einem Routineprozess der Lebensmittelindustrie zu werden zeigt sich in allen Teilen der Arbeit, die folglich einen wesentlichen Beitrag zur erfolgreichen Zulassung der KADP-Technologie im Lebensmittelsektor beiträgt

Thermal Impact on the Culturable Microbial Diversity Along the Processing Chain of Flour From Crickets (Acheta domesticus)

The role of insects for human consumption has lately increased in interest and in order to deliver safe and high-quality raw materials and ingredients for food and feed applications, processing of insects is a major pre-requisite. For edible insects a thermal treatment and appropriate storage conditions are recommended to minimize the microbiological risk and the impact of processing methods on the microbial contamination needs to be considered and determined. Based on standard process conditions for the production of Acheta domesticus flour, different heating treatments were used to reduce the microbial load of A. domesticus. In addition, the drying temperature and drying time were varied to determine whether the required residual moisture of <5% can be achieved more quickly with consistent microbial quality. The influence of the process conditions on the microbial community of A. domesticus along the processing chain was finally investigated under optimized process conditions. The total viable count was reduced from 9.24 log10 CFU/gDM to 1.98 log10 CFU/gDM along the entire processing chain. While Bacillaceae, Enterobacteriaceae, Enterococcaceae, and yeast and molds were no longer detectable in the A. domesticus flour, Staphylococcaceae and mesophilic spore forming bacteria were still found in the flour. The results indicate that the steaming process is essential for effectively increasing microbial safety since this processing step showed the highest inactivation. It is recommended to not only evaluate the total viable count but also to monitor changes in microbial diversity during processing to ensure microbial safety of the final product. © Copyright © 2020 Fröhling, Bußler, Durek and Schlüter

Recovery and techno-functionality of flours and proteins from two edible insect species: Meal worm (Tenebrio molitor) and black soldier fly (Hermetia illucens) larvae

Depending on the species, edible insects are highly nutritious and thus represent a noteworthy alternative food and feed source. The current work investigates the protein extractability and techno-functionality of insect flour fractions recovered from Tenebrio molitor and Hermetia illucens. T. molitor and H. illucens flours contained about 20% crude fat and 60% and 36 % crude protein, respectively. Defatting reduced the crude fat content to 2.8% (T. molitor) and 8.8% (H. illucens) and increased the crude protein content to 68% and 47%, respectively. To isolate proteins from the flours, protein solubility was optimized by varying the pH, the ionic strength, and the extraction temperature of the solvent. All products and by-products accumulated in the protein production process were characterized by composition, selected techno-functional properties, protein solubility, composition and structure as well as their microbial load

Recovery and techno-functionality of flours and proteins from two edible insect species: Meal worm (Tenebrio molitor) and black soldier fly (Hermetia illucens) larvae

Depending on the species, edible insects are highly nutritious and thus represent a noteworthy alternative food and feed source. The current work investigates the protein extractability and techno-functionality of insect flour fractions recovered from Tenebrio molitor and Hermetia illucens. T. molitor and H. illucens flours contained about 20% crude fat and 60% and 36 % crude protein, respectively. Defatting reduced the crude fat content to 2.8% (T. molitor) and 8.8% (H. illucens) and increased the crude protein content to 68% and 47%, respectively. To isolate proteins from the flours, protein solubility was optimized by varying the pH, the ionic strength, and the extraction temperature of the solvent. All products and by-products accumulated in the protein production process were characterized by composition, selected techno-functional properties, protein solubility, composition and structure as well as their microbial load

Effect of blanching plus fermentation on selected functional properties of mealworm (Tenebrio molitor) powders

The aim of this study was to determine the effect of blanching followed by fermentation of mealworms (Tenebrio molitor) with commercial meat starter cultures on the functional properties of powders produced from the larvae. Full fat and defatted powder samples were prepared from non-fermented and fermented mealworm pastes. Then the crude protein, crude fat, and dry matter contents, pH, bulk density, colour, water and oil binding capacity, foaming capacity and stability, emulsion capacity and stability, protein solubility, quantity of free amino groups, and protein composition of the powders were evaluated. Regardless of the starter culture used, the blanching plus fermentation process reduced the crude and soluble protein contents of the full fat powders and in general impaired their water and oil binding, foaming, and emulsifying properties. Defatting of the powders improved most functional properties studied. The o-phthaldialdehyde assay revealed that the amount of free amino groups was higher in the fermented powders while sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the soluble proteins of the fermented powders were composed of molecules of lower molecular mass compared to non-fermented powders. As molecular sizes of the soluble proteins decreased, it was clear that the protein structure was also modified by the fermentation process, which in turn led to changes in functional properties. In general, it was concluded that fermentation of mealworms with blanching as a pre-treatment does not contribute to the functional properties studied in this work. Nevertheless, the results confirmed that the properties of non-fermented powders are comparable to other food protein sources. © 2020 by the authors

Sustainable food protein supply reconciling human and ecosystem health: A Leibniz Position

Many global health risks are related to what and how much we eat. At the same time, the production of food, especially from animal origin, contributes to environmental change at a scale that threatens boundaries of a safe operating space for humanity. Here we outline viable solutions how to reconcile healthy protein consumption and sustainable protein production which requires a solid, interdisciplinary evidence base. We review the role of proteins for human and ecosystem health, including physiological effects of dietary proteins, production potentials from agricultural and aquaculture systems, environmental impacts of protein production, and mitigation potentials of transforming current production systems. Various protein sources from plant and animal origin, including insects and fish, are discussed in the light of their health and environmental implications. Integration of available knowledge is essential to move from a dual problem description (“healthy diets versus environment”) towards approaches that frame the food challenge of reconciling human and ecosystem health in the context of planetary health. This endeavor requires a shifting focus from metrics at the level of macronutrients to whole diets and a better understanding of the full cascade of health effects caused by dietary proteins, including health risks from food-related environmental degradation