Wilfried Andlauer

Rosa canina L. powders are rich in bioactive compounds; however, thermal processing and carrier addition can markedly alter their composition, affecting nutritional quality, safety and potential health effects. This study assessed the impact of juice pasteurization, followed by freeze-drying and spray drying with maltodextrin, inulin, trehalose, or palatinose, on amino acids, sugars, phenolic compounds, and Maillard reaction products. In carrier-added samples, total amino acid content ranged from 364.6 to 430.4 mg/100 g dry matter (DM). Tryptophan and γ-aminobutyric acid (GABA) were proposed as indicator compounds, with their distinct stability patterns under pasteurization and drying providing a reliable measure of processing effects while representing both essential (tryptophan) and non-essential (GABA) amino acids of nutritional relevance. Carriers reduced total sugar content ≈ 2.5-fold (from 16.7 to 6.7 g/100 g powder DM) but modified sugar profiles. Powders obtained from pasteurized juice with inulin showed the highest level of free amino groups (0.49 g N-α-acetyl-L-lysine/100 g powder DM), the lowest fructosamine content (44.8 mmol DMF/100 g powder DM), and total phenolics of 10.4 g GAE/100 g powder DM. Fructosamine, an early Maillard reaction marker, proved valuable for predicting powder quality, with lower levels linked to pasteurization and carriers with low glycation potential. Acrylamide was absent in all samples (LC–MS/MS), confirming chemical safety. Processing parameters and carrier type were key determinants of nutritional composition and safety, with inulin-based powders from pasteurized juice offering a balanced profile of free amino acids and phenolics, while minimizing fructosamine formation. The combined use of amino acid profiling, phenolic quantification, and early Maillard reaction markers provides a powerful approach for quality evaluation of fruit-based powders within glycoscience.

The solid-state fermentation (SSF) of agro-industrial by-products such as okara, pomegranate peel, and cranberry pomace presents a sustainable approach to enhance the release of bioactive compounds. This study investigated the effects of different microbial cultures—Rhizopus oligosporus, Aspergillus oryzae, Streptococcus thermophilus, and a co-culture of R. oligosporus and S. thermophilus—on the bioconversion of bioactive compounds in 100% okara, okara with 2% pomegranate peel, and okara with 1% cranberry pomace. The objective was to assess whether co-culture fermentation with molds and S. thermophilus augments the release of bioactive compounds in okara-based fermentations through synergistic enzymatic activity. Over a period of 72 h, isoflavone transformation (daidzin, daidzein, genistin, and genistein), pH evolution, and water activity were assessed. The co-culture system exhibited improved bioconversion, leading to significant (p < 0.01) increases in daidzein and genistein in pure okara compared to the starting material. The highest polyphenol content (0.908 mg/g) and antioxidant capacity (24.9 mg Trolox eq/g) were recorded in 100% okara. However, pomegranate peel inhibited β-glucosidase activity, delaying the release of isoflavone aglycones. These findings confirm that co-culture fermentation is an effective strategy for enhancing the bioactive properties of okara-based fermentations. This facilitates the release of bioactive aglycones and supports the upcycling of agro-industrial by-products into functional food ingredients. Future research should focus on optimizing fermentation parameters to further enhance the release of bioactive compounds.

Rosehip is of notable scientific interest due to its rich content of bioactives and its wide-ranging applications in nutrition, cosmetics and pharmaceuticals. The valorization of rosehip by-products, such as pomace, is highly significant for promoting sustainability. This study investigates the development of rosehip-based powders and beverage prototypes derived from both juice and pomace to evaluate the potential use of pomace in instant beverage design and compare it with juice-based formulations. Three matrices were evaluated: non-pasteurized and pasteurized juice, as well as non-pasteurized pomace preparations. Powders were produced by freeze- and spray drying using maltodextrin, inulin and unconventional carriers, i.e., palatinose and trehalose. The results demonstrated that carrier addition significantly influenced the physical and techno-functional properties of the powders, such as moisture content (below 10%), water activity (below 0.35), solubility (above 85%), and color indexes (yellowness and browning). The water absorption capacity varied with drying techniques, particularly for inulin-enriched samples, while the matrix type affected the ascorbic acid content. Non-pasteurized pomace powders exhibited a higher antioxidant capacity (67.7 mmol Trolox/100 g dry matter) than their juice counterparts (52.2 mmol Trolox/100 g dry matter), highlighting the potential of the pomace matrix for beverage production. Because of their favorable properties, spray-dried samples were also selected for reconstitution into prototype beverages, among which those obtained from pomace showed a higher antioxidant potential. An analysis of particle sizes, which ranged between 34 nm and 7363 nm, revealed potential interactions between the carrier and matrix, reflected in the distinct behavior of carrier-only samples. Both the carrier type and the matrix significantly contributed to the final properties of the beverages, providing valuable insights for the design of functional food products.

Plant biologists have long used various model organisms, such as Arabidopsis thaliana, to study biological processes. The emergence of algal model organisms in recent years greatly facilitated plant research due to their compact genomes with a very low level of functional redundancy and their physiological properties. Here, the green microalga Chlorella vulgaris has been used as a model organism to study the effect of whey hydrolysates against heat stress in vascular plants. Cell density in culture, as well as chlorophyll and carotenoid concentrations, were monitored during an initial growth phase, followed by a heat stress phase and a subsequent recovery phase. Results showed that whey hydrolysates promoted the recovery of heat-stressed C. vulgaris and showed improved growth rates and generation times after heat stress compared to cells grown in BG-11 only. Similarly, the production of chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids was improved in comparison to cells grown only in BG-11. The results may aid the development of novel biostimulants that protect crops from climate change due to higher throughput and shorter study times compared to traditional plant models.

Due to global warming, agricultural production systems are exposed to increasing abiotic stresses, which threaten an economically and environmentally sustainable food production. Innovative environmentally friendly solutions are needed to cope with climate-related risks and to reduce the use of high amounts of synthetic agrochemicals. A promising solution to foster sustainable agriculture involves the use of biostimulants. This strategy, however, is not adopted by the industry to a great degree due to the scarce number of reproducible effects observed in published studies as well as the lack of fundamental knowledge about their mode of action. Biostimulants are substances that positively impact plant physiology by enhancing growth, improving fruit quality, and increasing stress resilience. Among these, protein hydrolysates stand out as a particularly promising category. However, their precise mechanisms of action and the optimal conditions for their application are still not fully understood. This project aims to develop peptide-based biostimulants in a reproducible manner, ensuring their availability for use in plant model systems under strictly controlled conditions. To achieve this, various protein hydrolysates will be produced through the enzymatic hydrolysis of whey, a by-product of cheese production. These hydrolysates will be employed in subsequent studies within plant model systems.

The study investigated the impact of Lonicera caerulea L. juice matrix modification and drying techniques on powder characteristics. The evaluation encompassed phenolics (514.7–4388.7 mg/100 g dry matter), iridoids (up to 337.5 mg/100 g dry matter), antioxidant and antiglycation capacity, as well as anti-ageing properties of powders produced using maltodextrin, inulin, trehalose, and palatinose with a pioneering role as a carrier. Spray drying proved to be competitive with freeze drying for powder quality. Carrier application influenced the fruit powder properties. Trehalose protected the phenolics in the juice extract products, whereas maltodextrin showed protective effect in the juice powders. The concentrations of iridoids were influenced by the matrix type and drying technique. Antiglycation capacity was more affected by the carrier type in juice powders than in extract products. However, with carrier addition, the latter showed approximately 12-fold higher selectivity for acetylcholinesterase than other samples. Understanding the interplay between matrix composition, drying techniques, and powder properties provides insights for the development of plant-based products with tailored attributes, including potential health-linked properties.

Oil extracted from walnuts leaves behind large amounts of defatted press cake that still retains valuable nutrients. Solid state fermentation (SSF) is a promising method to liberate bioactive compounds from food by-products. Aspergillus oryzae, Rhizopus oligosporus, and Streptococcus thermophilus possess the necessary enzymes to utilize these nutrients from the walnut press cake (WPC) and convert walnut ellagitannins into ellagic acid and urolithins. This study conducted SSF with WPC to release ellagic acid from ellagitannins and form urolithins. The growth of the two filamentous fungi could be observed visually and the growth of Streptococcus thermophilus was confirmed by plate count technique. Extracts from fermented products were subjected to analysis using HPLC–DAD to measure the release of ellagic acid from ellagitannins. Additionally, a more sensitive UHPLC–MS method was employed to screen fermented samples for urolithin A. The ellagic acid content exhibited no perceptible change but was already present in the press cake before and after all fermentations. Urolithin A was undetectable, even with the more sensitive MS method. All studies showing urolithin A formation were conducted under anaerobic conditions. This might be a basic prerequisite for the transformation of ellagic acid to urolithins.

The essential oils of five Vietnamese Syzygium species (Syzygium levinei, S. acuminatissimum, S. vestitum, S. cumini, and S. buxifolium) were first hydro-distilled and analyzed using GC-FID/MS (gas chromatography–flame ionization detection/mass spectrometry). Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids were the main chemical classes in these oils. All these essential oils showed good–excellent antimicrobial activities against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, and the yeast Candida albicans. S. levinei leaf essential oil, rich in bicyclogermacrene (25.3%), (E)-β-elemene (12.2%), (E)-caryophyllene (8.2%), and β-selinene (7.4%), as well as S. acuminatissimum fruit essential oil containing (E)-caryophyllene (14.2%), α-pinene (12.1%), caryophyllene oxide (10.9%), β-selinene (10.8%), α-selinene (8.0%), and α-humulene (5.7%), established the same MIC value of 8 µg/mL against E. faecalis and B. cereus, which were much better than the positive control streptomycin (MIC 128–256 µg/mL). The studied essential oils showed the potential to defend against mosquitoes since they caused the 24 and 48 h LC₅₀ values of less than 50 µg/mL against the growth of Culex quinquefasciatus and Aedes aegypti larvae. Especially, S. buxifolium leaf essential oil strongly inhibited Ae. aegypti larvae with 24 and 48 h LC₅₀ values of 6.73 and 6.73 µg/mL, respectively, and 24 and 48 h LC₉₀ values of 13.37 and 10.83 µg/mL, respectively. These findings imply that Vietnamese Syzygium essential oils might have potential for use as supplemental antibacterial agents or as “green” alternatives for the control of mosquitoes.