Panagiotis Kandylis

Nowadays, there is an increasing demand for high-protein sustainable and functional foods, driven by the shifting of consumers’ dietary preferences and environmental concerns. All these have accelerated the development of hybrid dairy products. This review provides a unique comprehensive overview of hybrid dairy products, formulated through partial substitution of dairy with plant proteins from legumes, cereals, seeds, and microalgae. Therefore, it evaluates multiple dairy products and plant protein sources simultaneously, and provides broader and deeper insight on key formulation approaches, major challenges, and future opportunities for the development of more sustainable hybrid dairy products. Emphasis is placed on the effects on formulation, physicochemical properties, rheological behavior, texture, microstructure, fermentation dynamics, microbial quality, nutritional attributes, sensory characteristics, and sustainability. The functional and technological properties of dairy matrices are influenced and strongly depend on plant protein source, substitution level, and processing conditions. Hybridization enhances protein content, dietary fiber, and maintains microbial viability and probiotic potential. However, challenges remain related to gel stability, off-flavor development, color changes, antinutritional factors, and regulatory issues. Fermentation and advanced processing technologies emerge as key tools to mitigate some of these limitations. Hybrid dairy products represent a promising and flexible strategy to reduce the environmental footprint of dairy products while preserving their nutritional and sensory strengths, contributing to more sustainable food production systems. Future research should prioritize optimized protein combinations, comprehensive life cycle assessments, and consumer-centered studies to support successful product development and commercialization.

Grape pomace, a key winemaking by-product, is rich in bioactive compounds but largely underutilized. When not discarded, it is mainly used for low-value applications, though its potential for adsorption or immobilization has been shown. This study explores its dual application by evaluating the efficiency of simultaneous fining and malolactic fermentation of wine using lactic acid bacteria immobilized on grape pomace. Grape pomace powder was used to immobilize Oenococcus oeni and Lactiplantibacillus plantarum cells, evaluating the effect of grape pomace type (red/white) and freeze-drying of the immobilized bacteria on both applications. Efficiency was assessed by measuring pH, malic acid consumption rate, anthocyanin and tannin removal rate, total polyphenol index, and color parameters. Immobilization efficiency of lactic acid bacteria reached values of up to 93.5% for O. oeni and 95.1% for L. plantarum , while the former showed higher pH increase during malolactic fermentation despite the higher residual malic acid levels. Fining with grape pomace reduced anthocyanin and tannin content by up to 47% and 46.7%, respectively, whereas freeze-drying enhanced fining efficiency, particularly for tannin removal, and significantly influenced wine color. To the best of our knowledge, this is the firststudy to demonstrate the use of grape pomace as a dual-function bioresource that simultaneouslyserves as a fining agent and as an immobilization carrier for lactic acid bacteria during wine malolacticfermentation. The findings provide valuable insights into the potential applications of grape pomace, contributing to the advancement of biotechnological processes in winemaking and offering new approaches for improving wine quality by adapting sustainable and chemical-free technologies. Graphical Abstract

Nowadays, there is interest in yogurts and fermented milks with incorporated fruits to fulfill the growing demand for healthier, nutritional, and functional foods. In the present study, the potential of apple pulp incorporation into yogurts was evaluated. Apple pulps from five cultivars (Gala, Starking, Jonagold, Golden, and Granny Smith) were characterized for their antioxidant activity and total phenolic content, with Granny Smith pulp selected for further application due to its superior functional properties. Apple pulp (0–15% w/w) significantly influenced the acidification kinetics by lowering the initial pH and reducing fermentation time. The viability of yogurt starters remained above 10⁸ CFU/g throughout 28 days, fulfilling FAO/WHO criteria, although in yogurts with apple pulp, it was found to significantly decrease in a concentration-dependent manner compared to the control. Quality analyses revealed that apple pulp improved water-holding capacity and reduced syneresis. The antioxidant activity and total phenolic content of yogurts increased proportionally with apple pulp concentration, showing strong positive correlations. Yogurts containing 10–15% w/w apple pulp exhibited the most pronounced functional enhancements. These findings suggest that apple pulp serves as a promising sustainable natural ingredient for producing functional yogurts with improved health-promoting properties due to the antioxidant potential of apple-derived phenolics.

Fresh apple pulp from the Granny Smith variety was used at different levels (5–15% w/w) for yogurt production. Color, texture, microstructure, aroma, and sensory analyses were used to evaluate the effect of the apple pulp on the main characteristics of yogurt. Yogurts with apple pulp presented a lower brightness (L*) and an increased redness (a*) and yellowness (b*), which were significantly affected by the apple pulp concentration. The texture analysis revealed an improved consistency and reduced syneresis, leading to a creamier and more stable product. The aroma profile of yogurts was enriched, presenting higher ester contents. Confocal laser scanning microscopy showed that the incorporation of modest quantities of apple pulp resulted in the formation of initially denser networks, while at elevated levels, an enhanced microscopic phase separation occurred. A 5% apple pulp addition achieved a balance between enhancing flavor and texture retention while maintaining high overall acceptability, as was also confirmed by the sensory evaluation.

Winemaking generates significant amounts of byproducts, mainly grape pomace, which is composed of skins, seeds, and stems. Rich in phenolic compounds with antioxidant properties, grape pomace is often underutilized in low-value applications such as compost or animal feed. Recent research highlights its potential as a sustainable alternative to conventional fining agents, such as bentonite, commonly used to improve wine clarity, stability, and sensory attributes. However, previous studies have been limited in scope, focusing on selected wine parameters or narrow experimental conditions. This study explored the use of red and white grape pomace as fining agents for Mavrodaphne red wine, evaluating their effects on anthocyanin level, tannin content, total polyphenol index, chromatic properties, and aromatic profile across varied dosages and contact times. The results indicated that grape pomace, either from red or white grapes, achieved comparable or superior tannin and anthocyanin removal and chromatic enhancement relative to commercial fining agents, without significantly altering aromatic complexity. The findings underscore grape pomace’s suitability as a natural, vegan-friendly, and sustainable fining option, aligning with consumer preferences for cleaner-label wines. This study promotes the adoption of grape pomace in winemaking, supporting waste valorization and advancing sustainable practices within the industry.

Probiotics are widely recognized for their health benefits, but their viability during food processing and digestion poses significant challenges. The present study evaluated the impact of incorporating apple fibers into yogurt on the viability of the probiotic strain Lacticaseibacillus casei ATCC 393 during production, storage, and simulated gastrointestinal digestion. Apple fibers, a by-product of apple processing, were used as a prebiotic ingredient due to their functional and technological benefits. The incorporation of apple fibers increased probiotic viability during 28 days of refrigerated storage, improving it from 90.4% in the control yogurt to 93.9%. Under simulated gastrointestinal conditions, yogurt alone acted as a protective matrix, preserving probiotic viability, during gastric (71.0% at pH 2 after 3 h) and intestinal digestion (73.3% at 0.3% bile salts after 6 h). The inclusion of apple fibers further enhanced this protection, reducing probiotic viability loss in both gastric (81.9% at pH 2 after 3 h) and intestinal (79.0% at 0.3% bile salts after 6 h) environments. Similar results were obtained using the INFOGEST 2.0 static protocol. After the completion of the protocol (oral, gastric and intestinal phase) a viability of 71.1% (6.61 logCFU/g) was observed in the yogurt with apple fibers compared to 64.5% (6.10 logCFU/g) in the control yogurt. This enhanced protection could be attributed to the potential prebiotic properties of apple fibers, including their pectin and cellulose content, which may shield probiotics from acidic and enzymatic degradation. These findings highlight the potential of apple fiber-enriched yogurt as a functional food that supports probiotic viability during storage and throughout gastrointestinal transit. These insights may open the way for developing new food products with enhanced health benefits, aligning with growing consumer demand for functional foods.

Wine lees, the residue left behind after racking or bottling of wine, are predominantly composed of dead yeast cells, ethanol, phenolic compounds, and tartrates. Yeast extract (i.e., commercial yeast extract), a highly nutritious powder derived from commercially cultivated yeast biomass, is commonly used in nutrient media as a nitrogen source. In the context of by-product valorization, wine lees could potentially be used to produce a substitute for commercial yeast extract (CYE). In our study we investigated the growth and fermentative ability of two major winemaking microorganisms, Lactiplantibacillus plantarum and Saccharomyces cerevisiae, in culture media containing a wine lees yeast extract (WLYE) and a CYE. The effects of yeast extract type, concentration, and initial cell concentration (y₀) on key kinetic parameters—maximum specific growth rate (μ_max), lag phase duration (λ), and maximum cell concentration (y_max)—were evaluated. For L. plantarum, the results showed that using a WLYE led to similar kinetic parameters to those obtained with a CYE, with λ being unaffected by y₀ in samples containing a WLYE. For S. cerevisiae, simultaneous addition of both yeast extracts led to increased μ_max values (up to 0.136 h⁻¹) compared to individually added yeast extracts, although this negatively affected λ and y_max. Current research on wine lees is mainly focused on using them as a substrate to produce valuable metabolites through fermentation, overlooking the potential industrial applications of the nutrient-rich autolysate. The findings of this study appear promising for the holistic valorization of wine lees, contributing towards the concepts of sustainability and circular economy.

Research background. Nitrite salts are among the most used preservatives in meat products as they ensure their safe consumption. Despite their positive effects on food safety and stability, many side effects on human health have been reported, leading to the need to reduce their use. Therefore, the aim of this study is to produce veal products with low nitrite content through low diffusion of potassium nitrite and to study their microbiological characteristics. Experimental approach. Edible tubular cellulose from leaf celery was produced and KNO2 was encapsulated in this material. This was achieved in two ways: by impregnation of tubular cellulose in a KNO2 solution under stirring and using starch gel as a stabilizer. Two samples of impregnated cellulose were applied on the surface of two veal samples of which one was stored at room temperature and the other at 3 °C. Similarly, two samples of cellulose with starch gel were applied on the surface of two veal samples of which one was stored at room temperature and the other at 3 °C. The KNO2 diffusion in different depths of the meat was measured and its effect on the microbiological characteristics of the meat was evaluated. Τhe experiment was carried out in duplicate. Results and conclusions. A satisfactory percentage of about 70 % of the initially encapsulated amount of KNO2 was diffused in the meat, while the rest remained in the pores of the delignified leaf celery. The migrating amount of KNO2 proved to be effective in preserving meat, as the microbiological load decreased significantly (especially within the first 12 h, from a decrease of 0.6 log CFU/g up to 2.4 log CFU/g). Novelty and scientific contribution. The demand for meat products with low nitrite content is constantly increasing and the results of the present study are promising for the development of this technology in scale-up systems and on an industrial scale. This innovative approach could lead to products with controlled diffusion of the preservatives.

Functional foods are gaining the attention of consumers, who demand foods that can fulfil nutritional needs, help maintain a balanced diet and also possess a beneficial impact on human health. Beer is a carbonated alcoholic beverage with worldwide acceptance and its moderate consumption has been associated with anti-inflammatory and antioxidant properties, benefits for bone density, and the prevention of coronary heart disease. Beer also presents better nutritional composition compared to the majority of alcoholic beverages, containing sufficient amount of nutrients like carbohydrates, protein and amino acids, minerals, vitamins, and polyphenols, without the addition of artificial additives or preservatives. Polyphenols, originated from malt and hops are the major natural antioxidants in beer that contribute to its functional properties. In order, to further increase these beer characteristics, nowadays, special beers, like low-alcohol or even non-alcoholic beers, gluten-free beers, craft beers, unpasteurized, unfiltered, with the addition of fruits, juices, plant extracts etc., are available in the market or under research. Another important feature of functional foods is their association with the presence of probiotics. However, one of the main challenges of exerting probiotics' health effects, is the maintenance of high viability (> 106 CFU/g) during food processing and storage. However, as beer typically contains hop ISO-a-acids, ethanol, and low pH, which prevent the growth and survival of probiotic lactic acid bacteria, the use of new strategies, like encapsulation, is crucial to retain their survival. Therefore, in the present study the main nutritional features and functional characteristics of beers (both regular and special beers) are highlighted, in combination with the recent research activities in the field. Taking into account the beer production in Greece some recent experimental works are presented focusing on the addition of fruit juices in beer production, the use of microencapsulation to enhance beer probiotication, and evaluating the potential superiority of craft and nonalcoholic beers compared to regular beers. The present work highlights the great potential of beer (especially non-alcoholic) to serve as functional food and vehicle of probiotic delivery.