Background: Olive stone (OS) has emerged as a promising by-product with potential applications in food and feed formulations, owing to its unique properties. Despite growing interest in recent years, research dedicated to the comprehensive evaluation of OS remains limited. Aim: This review aimed to elucidate the structure, physical and chemical properties of OS, provide an overview of its diverse application areas, and highlight its potential utilization in food and feed formulations through case studies and recent advancements. Methods: A systematic literature search was conducted using prominent databases, including Google Scholar, Web of Science, PubMed and Scopus, with a focus on studies published in recent years. The search strategy employed keywords such as olive, olive by-products, olive stone composition, valorization areas, use of agricultural wastes in food. Relevant publications in English or Turkish were considered, resulting in a reference list of 97 articles that were critically reviewed and cited. Results: OSs are a significant by-product generated during the olive oil extraction and pitted table olive production, constituting approximately 18-22% of the olive fruit. OS possesses a lignocellulosic composed primarily of hemicellulose, cellulose and lignin. Although its current predominant use is as fuel due to its high calorific value, OS exhibits potential for diverse applications owing to its rich composition of fat, protein, bioactive phenolic compounds and dietary fiber. Potential valorization pathways include activated carbon production, oil extraction, furfural synthesis, plastic filling material, cosmetic formulations, biosorbents, resin production, and animal nutritional supplementation. Recent studies have increasingly explored the use of OSs as a functional food ingredient, with promising results demonstrating its efficacy as an antioxidant, nutraceutical and thickening agent in food formulations. Conclusion: This review underscores the multifaceted potential of OS, particularly in food and feed applications. The valorization of OS aligns with sustainable waste management practices and offers innovative opportunities for enhancing food and feed formulations. Keywords: Olive, olive stone, waste management, waste valorization, agricultural by-product.

Extra virgin olive oils obtained from the Ayvalık, Memecik, Gemlik, Çekişte, and Sarı Ulak Turkish cultivars were evaluated to determine their chemical composition, quality classification, authenticity indicators, and sensory characteristics. Standard quality parameters, including free fatty acidity, peroxide value, and ultraviolet absorbance (K232, K270), were analyzed in accordance with International Olive Council (IOC) regulations. The majority of the samples met the criteria for extra virgin olive oil. The oleic acid content varied by variety and region, with Ayvalık and Memecik showing notably high levels. Sterol profile analyses revealed distinctive chemical markers that indicate authenticity and quality. Sensory analysis results showed that regional differences had a significant impact on aroma, taste, and overall acceptability. Oils from Ayvalık and Memecik received high scores for positive sensory attributes such as fruitiness, bitterness, and pungency. The results show that the chemical and sensory qualities of olive oil are directly influenced by both genetic diversity and growing conditions, which underscores the importance of conserving local varieties and promoting regional production methods.

This study evaluated the sustainability of removing phenolic compounds from olive mill effluents using a nanobiochar synthesized from olive pomace. Catechol, tyrosol, hydroxytyrosol, and homovanillic alcohol were chosen as model pollutants due to their presence in agro-industrial wastewater. The surface morphology, elemental composition, crystallographic structure, functional groups, porosity, and thermal stability of the nanobiochar were investigated by SEM, EDX, XRD, FTIR, BET analysis, and TGA/DTA. The developed nanobiochar exhibited a predominantly amorphous carbon structure, enriched in carbon (85.6%), with localized graphitic domains. Its mesoporous architecture (S_BET = 15.478 m² g⁻¹; Dp = 2.14 nm) promotes accessibility to active sites, while its thermal stability confirmed its suitability for adsorption applications. In this batch adsorption study, the technological aspect considered is the influence of operating parameters on adsorption efficiency, using kinetic and equilibrium models. Pseudo-first-order and pseudo-second-order kinetic models, as well as Freundlich and Langmuir isotherms, were used to analyze the experimental data. The pseudo-second-order model proved to be the most suitable for describing adsorption, suggesting that the process is primarily dominated by chemisorption. Similarly, the Langmuir model gave the least satisfactory results regarding equilibrium data, indicating monolayer adsorption on homogeneous active sites. The adsorption capacity of phenolic compounds was variable. The highest adsorption capacities were observed for catechol (250 mg g⁻¹), tyrosol (19.23 mg g⁻¹), homovanillic alcohol (15.38 mg g⁻¹), and hydroxytyrosol (13.16 mg g⁻¹). The results of this research indicate that adsorption affinity depends on molecular structure and electronic properties. Furthermore, computer modeling based on molecular simulations and electronic descriptors was performed to explain the adsorption mechanism. Linear regression, principal component analysis, and elastic regression revealed strong correlations between adsorption parameters and molecular descriptors. These results demonstrate that olive pomace-based nanobiochar is an environmentally friendly adsorbent for the treatment of phenolic effluents, with adsorption primarily controlled by surface interactions.

This study aimed to encapsulate Lactobacillus acidophilus LA-5 (LA-5) and Bifidobacterium animalis subsp. lactis BB-12 (BB-12) in alginate and pectin, and to determine the effects of acid and bile resistance. The emulsion method was used; different gel and CaCl2 concentrations and stirring rate were studied comparatively for the characterization of microcapsules. Alginate microcapsules were smaller and exhibited agglomeration behavior, while pectin microcapsules were fairly homogeneous and had a smooth shape. Encapsulation efficiency (EE) percentages of the bacteria cells encapsulated with alginate and pectin varied within a very narrow range of 83 to 85%. The size of microcapsules increased as the gel concentration increased, and decreased as the CaCl2 concentration and stirring rate increased. Microencapsulated cells had more acid and bile resistance than free cells. No significant difference was found between alginate and pectin microcapsules of the two strains in terms of acid and bile resistance. The probiotic strains encapsulated with pectin and alginate maintained higher levels of viability under acid conditions at pH 2 and 3 than at pH 1 after 24 hours of incubation.

Table olives gain their unique taste and aroma as a result of fermentation, which is applied together with debittering process. In this study, Domat green and Gemlik black olives, which are very common Turkish cultivars, were used for table olive production and debittering was carried out by sodium bicarbonate (NaHCO₃). Fermentation was monitored with pH, titratable acidity, reducing sugar, total phenol content and microbiological analyses over 120 days fermentation period. Lactic acid bacteria (LAB) were identified by API 50 CHL and the effect of NaHCO₃ on LAB profile was evaluated. It was determined that there were 3 LAB species, namely: Lactobacillus plantarum (6 isolates, 12%), Lactobacillus pentosus (27 isolate, 54%) and Lactococcus mesenteroides ssp. mesenteroides (17 isolates, 34%). Most of the isolates identified as Lactobacillus were identified as L.pentosus. L.plantarum species was isolated only from green table olives and was not found in isolates from black table olive samples.