Fungi, which are widely distributed across the Earth, have successfully managed to colonize cold environments (e.g., polar regions, alpine ecosystems, and glaciers) despite the challenging conditions for life. They are capable of living in extremely harsh environments due to their ecological versatility and morphological plasticity. It is also believed that lower eukaryotes are the most adapted to life at low temperatures among microorganisms that thrive in cold environments. They play important ecological roles, contributing to nutrient recycling and organic matter mineralization. These highly specialized microorganisms have developed adaptation strategies to overcome the direct and indirect harmful influences of low temperatures. They have evolved a wide range of complex and cooperative adaptations at various cellular levels, including modifications to the cell envelope and enzymes, the production of cryoprotectants and chaperones, and the development of new metabolic functions. Adaptation to cold environments has made fungi an exciting source for the discovery of new cold-adapted enzymes (e.g., proteinases, lipases) and secondary metabolites (e.g., pigments, osmolytes, polyunsaturated fatty acids) for widespread use in biotechnology, food technology, agriculture, pharmaceutics, molecular biology, textile industry, and environmental bioremediation in cold climates. This review aims to provide a comprehensive overview of the adaptive strategies employed by psychrophilic yeasts and fungi, highlighting their ecological roles and biotechnological potential. Understanding these adaptive mechanisms not only sheds light on microbial life in extreme environments but also paves the way for innovative applications in the food industry and agriculture.

The volume of difficult-to-process keratin waste is increasing as a result of rising global meat production. If not properly managed, this waste can contribute to environmental pollution and pose a threat to human and animal welfare. An interesting and more sustainable alternative is therefore the bioconversion of keratin using microorganisms and their enzymes. This work aimed to isolate bacteria from soil samples and zoonotic keratins and to evaluate their enzymatic capacity to degrade α- and β-keratin wastes. A total of 113 bacterial strains were isolated from environmental samples and subjected to taxonomic identification using the MALDI-TOF MS technique and to a two-step screening for proteolytic and keratinolytic activity. The ability to degrade a β-rich keratin substrate was observed in almost all of the strains isolated from soil and horsehairs. In contrast, when an α-rich keratin substrate was used, the highest levels of hydrolysis were observed only for Ker39, Ker66, Ker85, Ker100, and Ker101. Strains with the highest biodegradation potential were identified using molecular biology methods. Phylogenetic analysis of 16S rDNA gene sequences allowed the assignment of selected keratinolytic microorganisms to the genera Exiguobacterium, Priestia, Curtobacterium, Stenotrophomonas, Bacillus, Kocuria, or Pseudomonas. The results of this study are a promising precursor for the development of new, more sustainable methods of managing keratin waste to produce high-value hydrolysates.

The aim of this study was to evaluate the potential of selected agri-food by-products—apple pomace extract from Malus domestica cv. ‘Grochówka’ and Roman chamomile (Chamaemelum nobile L.) hydrolate—as functional, sustainable ingredients for cosmetic applications. The work focused on their chemical composition, biological activity, formulation performance, and in vivo effects on skin condition. Volatile compounds, phenolic acids, and triterpenoids were analyzed by GC–MS, while total phenolic content, antioxidant capacity, and enzyme inhibitory activity were evaluated in vitro. An oil-in-water emulsion containing the by-products was formulated and, in a 14-day split-face study, assessed for its effects on skin hydration, elasticity, inflammation, sensitivity, pore visibility, and melanin index. Biochemical analyses have shown that chamomile hydrolate is characterized by very low antioxidant activity (DPPH 5.0 ± 1.25%, FRAP 0%) and weak protease inhibition (9.70 ± 1.84%). In contrast, apple extract contained a significant amount of polyphenols (23.94 ± 0.3 mg GAE/g) and showed strong antioxidant properties (DPPH 79.4 ± 2.12%, FRAP 70.56 ± 2.23%; IC₅₀ = 21.5 ± 0.196 mg/mL), which confirms the dominant role of phenolic compounds in its biological activity. This extract also demonstrated significant protease inhibition (60.88 ± 2.35%; IC₅₀ = 15.02 ± 0.47 mg/mL), while its lipase inhibition activity was moderate (10%), which may be beneficial from a cosmetic perspective. The obtained results indicate that apple extract is a valuable raw material with multifaceted biological potential. Overall, the results demonstrate that apple pomace extract and chamomile hydrolate can be effectively valorized as bioactive cosmetic ingredients, supporting both skin health benefits and circular economy principles in sustainable cosmetic formulation.

Apples are among the most consumed fruits worldwide. They serve as an excellent source of compounds that have a positive impact on human health. While new varieties of apples are being developed, numerous varieties have been forgotten. In this article, we present the results of research on 30 old apple cultivars, focusing on both qualitative and quantitative determination of antioxidant properties, and content of total phenolics, phenolic acids, triterpenoids and polyphenols. Our analyses show significant differences in the total content of each group of compounds between apple cultivars, as well as the phytochemical profile. The richest source of antioxidants was revealed to be ‘Reneta Blenheimska’ and ‘Książę Albrecht Pruski’ varieties, but the highest amount of phenolics had ‘James Grieve’ and ‘Kantówka Gdańska’ (KG). Among studied apples KG, ‘Krótkonóżka Królewska’ and ‘Grochówka’ (G) were the richest source of phenolic acids and polyphenols, whereas G, ‘James Grieve’ and ‘Krótkonóżka Królewska’ had the highest level of triterpenoids. Based on these findings, we selected two cultivars, G and KG, for further in vitro cell line-based studies. Based on biological activity analyses, we demonstrated not only antioxidant potential but also proapoptotic and cytoprotective properties within human-originated Caco-2 and HepG2 cell lines. In the era of a dynamically growing number of lifestyle diseases, it is particularly important to draw the attention of producers and consumers to the need to choose fruit varieties with the highest possible content of health-promoting compounds and, therefore, with the strongest health-promoting properties.

Agricultural residues are increasingly used as feedstocks for renewable heat and power generation, but their thermochemical conversion also produces secondary fractions that are often treated as problematic wastes. Condensates, tars, aqueous phases, bio-oil-derived liquids, chars, and ash-rich residues may cause corrosion, fouling, toxicity, microbial inhibition, or additional treatment costs. However, these streams may also contain recoverable chemicals, catalytic feedstocks, biodegradable carbon sources, or functional carbonaceous materials. This narrative review examines secondary fractions generated during the torrefaction, pyrolysis, gasification, and hydrothermal processing of agricultural waste as streams that can be analytically characterized and potentially valorized, rather than simply treated as unavoidable residues. Particular attention is given to the role of chromatographic, spectroscopic, elemental, thermal, and bulk physicochemical analyses in determining whether a fraction is suitable for separation, purification, catalytic upgrading, biological transformation, energy recovery, or controlled disposal. The review also highlights key research gaps, including inconsistent terminology, feedstock variability, excessive reliance on model compounds, insufficient quantitative chromatographic data, limited integration of chemical analysis with biological testing, and the scarcity of techno-economic and life-cycle assessments. An analytical-to-valorization decision framework is proposed to support more complete circular waste-to-energy systems.