Fruit and Vegetable Peel-Enriched Functional Foods: Potential Avenues and Health Perspectives

Unexplored Opportunities of Utilizing Food Waste in Food Product Development for Cardiovascular Health

PURPOSE OF REVIEW

Global food production leads to substantial amounts of agricultural and food waste that contribute to climate change and hinder international efforts to end food insecurity and poverty. Food waste is a rich source of vitamins, minerals, fibers, phenolic compounds, lipids, and bioactive peptides. These compounds can be used to create food products that help reduce heart disease risk and promote sustainability. This review examines the potential cardiovascular benefits of nutrients found in different food waste categories (such as fruits and vegetables, cereal, dairy, meat and poultry, and seafood), focusing on animal and clinical evidence, and giving examples of functional food products in each category.

RECENT FINDINGS

Current evidence suggests that consuming fruit and vegetable pomace, cereal bran, and whey protein may lower the risk of cardiovascular disease, particularly in individuals who are at risk. This is due to improved lipid profile, reduced blood pressure and increased flow-mediated dilation, enhanced glucose and insulin regulation, decreased inflammation, as well as reduced platelet aggregation and improved endothelial function. However, the intervention studies are limited, including a low number of participants and of short duration. Food waste has great potential to be utilized as cardioprotective products. Longer-term intervention studies are necessary to substantiate the health claims of food by-products. Technological advances are needed to improve the stability and bioavailability of bioactive compounds. Implementing safety assessments and regulatory frameworks for functional food derived from food waste is crucial. This is essential for maximizing the potential of food waste, reducing carbon footprint, and improving human health.

Phytochemistry, nutritional composition, health benefits and future prospects of Mespilus germanica L. (Medlar): A review

Mespilus germanica L., commonly known as medlar, is one of two species of the Rosaceae family. The medlar plant has a long history of use in gastronomy and healthcare. Medlar waste is used to extract hazardous heavy metals from contaminated water. The nutritional value of M. germanica fruits comes from their composition of carbohydrates, carotenoids, amino acids, organic acids, proteins, vitamins, fatty acids, and vital components. M. germanica fruit contains a high concentration of important phenolic components, which contribute to its anti-diabetic and antioxidant properties. Additionally, several studies have identified diverse biological properties of the M. germanica plant, including the cytotoxic, neurodegenerative, and antibacterial properties of its fruits and leaves. Scientists are investigating underutilized plant species to address sustainability issues in food production. This review study will provide a comprehensive examination of its chemical composition, medical applications, plant waste utilization, and potential biological activities.

LC-QTOF/MS-Based Profiling of the Phytochemicals in Ice Plant (Mesembryanthemum crystallinum) and Their Bioactivities

Recent assessments of the correlations between food and medicine underscore the importance of functional foods in disease prevention and management. Functional foods offer health benefits beyond basic nutrition, with fresh fruits and vegetables being particularly prominent because of their rich polyphenol content. In this study, we elucidated the phytochemicals in ice plant (Mesembryanthemum crystallinum), a globally consumed vegetable, using an LC-QTOF/MS-based untargeted detection method. The phytochemicals were clustered based on their structural similarity using molecular networking and annotated using the in silico tool for network annotation propagation. To identify the bioactive compounds, eight compounds were isolated from ice plant extracts. These compounds were identified using extensive spectroscopic methods, including 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Additionally, we evaluated the antioxidant and anti-inflammatory activities of all the isolates. Among the tested compounds, three showed antioxidant activity and all eight showed anti-inflammatory activity, demonstrating the potential of ice plant as a functional food.

Physicochemical Properties of Dried and Powdered Pear Pomace

Pear pomace, a byproduct of juice production, represents a valuable reservoir of bioactive compounds with potential health benefits for humans. This study aimed to evaluate the influence of drying method and temperature on pear pomace, specifically focusing on the drying kinetics, grinding characteristics, color, phenolic profile (LC-MS/MS), and antioxidant activities of the powder. Drying using the contact method at 40 °C with microwave assistance demonstrated the shortest duration, whereas freeze-drying was briefer compared to contact-drying without microwave assistance. Freeze-drying resulted in brighter and more easily comminuted pomace. Lyophilized samples also exhibited higher total phenolic compound levels compared to contact-dried ones, correlating with enhanced antioxidant activity. Twenty-one phenolic compounds were identified, with dominant acids being quinic, chlorogenic, and protocatechuic. Flavonoids, primarily isoquercitrin, and rutin, were also presented. Pear pomace dried via contact at 60 °C contained more quinic and protocatechuic acids, while freeze-dried pomace at the same temperature exhibited higher levels of chlorogenic acid, epicatechin, and catechin. The content of certain phenolic components, such as gallic acid and epicatechin, also varied depending on the applied drying temperature.

Comparison of different drying technologies for walnut (Juglans regia L.) pellicles: Changes from phenolic composition, antioxidant activity to potential application

The analysis of the phenolic profile in the walnut pellicle (WP) and its exploitability can help to promote the valorization of the industrial waste from walnut production. Three forms of 33 monomeric phenols in WPs were quantified based on our previously established LC-MS/MS method. The levels of protocatechuic acid and 4-hydroxybenzoic acid in the WPs were the highest, exceeding 400 μg/g. Antioxidant tests revealed that all three phenolic forms of WPs were effective antioxidants (IC50: 2.12-35.05 µg/mL). The findings also revealed that drying temperature had a substantial type-dependent effect on phenolics and their antioxidant ability in WPs. KEGG enrichment analysis found that drying method has the greatest impact on WPs phenols in six metabolic pathways. Besides, 11 active substances in WPs were identified by a compound-targeted activity screening approach, indicating that WPs could be used as a natural antioxidant source in the development of medical and nutraceutical products.

Food Application of Orange Seed Powder through Incorporation in Wheat Flour to Boost Vitamin and Mineral Profiles of Formulated Biscuits

The significance of conducting research for its application has been noted as a result of the rising global food production and waste generation. As a result, there is increasing interest in fruits and vegetable seeds that contain bioactive chemicals, such as those that are obtained from orange seeds. In the current work, orange seed powder replaced wheat flour at 0, 2.5, 5, 7.5, and 10% levels, to observe changes in physicochemical features of developed biscuits. Proximate analysis of orange seed powder and wheat flour revealed that orange seed powder has high fat, fiber, protein, and ash contents as compared to wheat flour, whereas moisture contents in wheat flour were high. In developed biscuits, the highest values (percentage) of ash (9.68 ± 0.04), fiber (6.79 ± 0.12), protein (10.42 ± 0.25), and fat (36.90 ± 0.55) were found in biscuits developed with 10% orange seed powder. Orange seed powder was a comparatively good source of both macro and micro minerals, as compared to wheat flour. High contents of selenium (5.32 ± 0.03), iron (2.12 ± 0.05), zinc (3.88 ± 0.12), and manganese (2.25 ± 0.04) mg/100 g, present in orange seed powder, were the prominent findings of this research work, as wheat flours were observed to be deficient in these trace minerals. Contents of calcium, magnesium, potassium, zinc, manganese, zinc, and selenium in control biscuits were found 20.51 ± 0.08, 17.29 ± 0.04, 46.12 ± 0.05, 1.06 ± 0.01, 1.97 ± 0.01, 0.12 ± 0.01, and 0.11 ± 0.01 mg/100 g, respectively, and replacement of wheat flour with 10% orange seed powder increased values of these minerals to 103.90 ± 0.35, 44.35 ± 0.50, 71.29 ± 0.32, 2.59 ± 0.4, 2.75 ± 0.02, 1.31 ± 0.01, and 2.02 ± 0.05 mg/100 g, respectively. Vitamins E and K, which were not detected in wheat flour, were present in orange powder in high amount, whereas B group vitamins, which were also present in wheat flour, were observed in significantly high quantities in orange seed powder. Increment in vitamin A, D, E, K, and B complexes was significant as a result of orange seed powder supplementation, except for vitamins B1 and B2, which were slightly decreased. Sensory evaluation revealed that a 5% replacement of orange seed powder provided good quality biscuits with acceptable colour, flavor, taste, texture, and overall acceptability. Orange seed powder could prove an important ingredient in the baking industry with the potential of promoting the nutritional value of foods.

Fruit waste: a current perspective for the sustainable production of pharmacological, nutraceutical, and bioactive resources

Fruits are crucial components of a balanced diet and a good source of natural antioxidants, that have proven efficacy in various chronic illnesses. Various kinds of waste generated from fruit industries are considered a global concern. By utilizing this fruit waste, the international goal of "zero waste" can be achieved by sustainable utilization of these waste materials as a rich source of secondary metabolites. Moreover, to overcome this waste burden, research have focused on recovering the bioactive compounds from fruit industries and obtaining a new strategy to combat certain chronic diseases. The separation of high-value substances from fruit waste, including phytochemicals, dietary fibers, and polysaccharides which can then be used as functional ingredients for long-term health benefits. Several novel extraction technologies like ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) could provide an alternative approach for successful extraction of the valuable bioactives from the fruit waste for their utilization as nutraceuticals, therapeutics, and value-added products. Most of these waste-derived secondary metabolites comprise polyphenols, which have been reported to have anti-inflammatory, insulin resistance-treating, cardiovascular disease-maintaining, probiotics-enhancing, or even anti-microbial and anti-viral capabilities. This review summarizes the current knowledge of fruit waste by-products in pharmacological, biological, and probiotic applications and highlights several methods for identifying efficacious bioactive compounds from fruit wastes.

Oscillatoria sancta Cultivation Using Fruit and Vegetable Waste Formulated Media and Its Potential as a Functional Food: Assessment of Cultivation Optimization

The most cost-effective technique to cultivate microalgae is with low-cost resources, like fruit and vegetable peels. This study examined the viability of culturing microalgae (Oscillatoria sancta PCC 7515) isolated from a waterlogged region of Punjab, India, in a low-cost medium (fruit and vegetable waste peels) for pharmaceutical use. 16S rRNA sequencing discovered O. sancta PCC 7515. Fruit and vegetable peels were mineralized and chemically analyzed. At a 5% Bacillus flexus concentration, fruit and vegetable peels were liquefied at room temperature for 24 h. Response Surface Methodology (RSM) was used to assess and improve important cultural variables. The RSM predicted the best results at 10 pH, 30 days of incubation, 5% inoculum concentration, and 5% fruit and vegetable waste liquid leachate. The optimum conditions yielded more biomass than the basal conditions (0.8001 g/L). O. sancta PCC 7515 produced more lipids, proteins, Chl a, and Chl b in a formulated alternate medium than standard media. This study shows that O. sancta PCC 7515 may thrive on fruit and vegetable peel media. Fruit and vegetable waste (FVW) media assure low-cost microalgae-based functional foods.

Valorization of fruit and vegetable processing by-products/wastes

Fruit and vegetable processing by-products and wastes are of great importance due to their high production volumes and their composition containing different functional compounds. Particularly, apple, grape, citrus, and tomato pomaces, potato peel, olive mill wastewater, olive pomace and olive leaves are the main by-products that are produced during processing. Besides conventional techniques, ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction (sub-critical water extraction), supercritical fluid extraction, enzyme-assisted extraction, and fermentation are emerging tools for the recovery of target compounds. On the other hand, in the view of valorization, it is possible to use them in active packaging applications, as a source of bioactive compound (oil, phenolics, carotenoids), as functional ingredients and as biofertilizer and biogas sources. This chapter explains the production of fruit and vegetable processing by-products/wastes. Moreover, the valorization of functional compounds recovered from the fruit and vegetable by-products and wastes is evaluated in detail by emphasizing the type of the by-products/wastes, functional compounds obtained from these by-products/wastes, their extraction conditions and application areas.

Exploring the Potential of Pomegranate Peel Extract as a Natural Food Additive: A Review

PURPOSE OF THE REVIEW

Pomegranate is one of the super fruit and a storehouse of several antioxidants and health-promoting compounds which can act as a natural food additive. The pomegranate processing industry generates huge quantities of by-products, particularly peels (50% of fresh fruit weight), that cause environmental pollution due to improper disposal. In this perspective, the present review article focuses on the chemical composition of pomegranate peel and its application as a natural food additive in different food products such as bakery, dairy, meat/meat products, fish/fish products, edible oils, and packaging materials.

RECENT FINDINGS

There is a continuous demand for processed foods exhibiting natural food additives over foods containing synthetic additives/colorants, which can cause serious health implications such as cancer with regular consumption. The food industry is looking for an alternative to synthetic/artificial food additives. To overcome these problems, pomegranate peel or its extract can be used as a natural biopreservative in food products that are prone to fat oxidation and microbial growth. Pomegranate peel contains bioactive compounds, especially tannins, phenolic acids, and flavonoids, which have nutraceutical value and possess higher antioxidant activity and antimicrobial properties. Due to these properties, pomegranate peel prevents lipid oxidation in fatty foods and can also retard the microbial growth.

Experimental Investigation and Modeling for the Influence of Adding Date Press Cake on Drinkable Yogurt Quality

The extraction of date syrup produces a large quantity of by-product known as date press cake (DPC). This study aimed to utilize valuable ingredients of the DPC by adding 0 (Control), 2, 4, and 6% (g/100 g) of its powder to drinkable yogurt before fermentation. The physicochemical properties, texture profile, and sensory evaluation of the treated DPC-based drinkable yogurt (DPC drinkable yogurt) were measured after fermentation and 5, 10, and 15 days of storage at 4 °C. The modeling of the most critical quality attributes, i.e., pH, acidity, syneresis, water holding capacity (WHC), viscosity, and color difference (ΔE), was conducted to predict their values based on the DPC percentage and storage period. The DPC drinkable yogurt’s total solids, protein, and fat ranged between 11.19–11.83, 3.10–3.42, and 2.26–2.34%, respectively. Adding 2–6% DPC slightly increased the pH of DPC drinkable yogurt and decreased its acidity (p > 0.05) during storage. Increasing the DPC percent in DPC drinkable yogurt decreased the syneresis value, and WHC increased during storage. The color parameters and viscosity of DPC drinkable yogurt recorded the highest value at the end of the storage period for all treatments and increased steadily with the increase in DPC. The evaluation of the prediction models indicated that the predicted values were close to the actual experimental values for pH (R2 = 0.779), acidity (R2 = 0.973), syneresis (R2 = 0.961), WHC (R2 = 0.989), viscosity (R2 = 0.99), L* (R2 = 0.919), a* (R2 = 0.995), b* (R2 = 0.922), and ΔE (R2 = 0.921). The textural analysis indicated that increasing the concentration of DPC in the DPC drinkable yogurt increased hardness (g), springiness, cohesiveness, and gumminess and decreased adhesiveness and resilience during cold storage. The evaluation of sensory acceptance during the cold storage of the DPC drinkable yogurt was conducted by 30 expert panelists. Each panelist received four cups of 10 mL drinkable yogurt treatments at 5–10 °C. The evaluation results indicated that adding 2% of DPC was closest in overall sensory acceptability to the control sample (p < 0.05). This study revealed the potential use of DPC in drinkable yogurt as a natural, functional, and low-cost ingredient to improve the fiber content, physicochemical properties, and overall acceptability. Therefore, the fermented DPC-based yogurt drink has the potency to be a practical, value-added, and novel alternative to dairy-based yogurt.

Effects of Pomegranate Peel Extract and/or Lactic Acid as Natural Preservatives on Physicochemical, Microbiological Properties, Antioxidant Activity, and Storage Stability of Khalal Barhi Date Fruits

The use of natural preservatives in the storage of fresh fruits is a promising approach to healthier and more sustainable food processing. The current study was conducted to evaluate the effect of pomegranate peel extract (PPE) and lactic acid (LA) as natural preservatives on the shelf life of Khalal Barhi date fruits. Physicochemical properties, antioxidant activity, color parameters, texture profile, sensory characteristics, and microbiological quality of date fruits were evaluated during six weeks of cold storage (4 ± 1 °C). The bioactive compounds in PPE were determined by HPLC analysis, which showed that PPE is a rich source of bioactive compounds, particularly phenolics and flavonoids. The results exhibited decreased moisture content (from 68.36–68.43 to 62.13–63.11%) and an increased soluble solids content (from 27.16–27.24 to 31.45–33.91%) in all samples with prolonged storage. Likewise, a slight decrease in the pH (from 6.00–6.28 to 4.89–5.29) with an increase in acidity (from 0.12–0.14 to 0.23–0.27%) during storage was observed. Generally, treated samples showed lower changes in moisture content, soluble solids content, pH, and acidity than the control. A decrease in total phenolic content (TPC) (from 8.22–12.36 to 3.19–5.17 mg GAE/g) and antioxidant activity (from 44.11–68.26 to 23.84–38.52%) of all samples was observed with progressed storage, meanwhile, the treatment with PPE significantly (p < 0.05) increased TPC with a concomitant increase in antioxidant activity and maintained higher values of both throughout storage. The results exhibited a decrease in L* (from 54.87–55.92 to 41.68–45.68) and b* (from 36.25–37.09 to 23.59–25.42) values of all samples, while the a* value of all samples increased (from 1.29–1.40 to 2.22–2.43) with storage. Dipping treatment in PPE solution improved the color, exhibited the lowest change in color parameters, and maintained better texture properties during storage. Similarly, sensory properties decreased (from 8.21–8.66 to 6.71–7.21) during storage with insignificant (p > 0.05) differences among samples. Dipping treatments inhibited the growth of yeasts and molds over time, with the lowest microbial count recorded in the PPE-treated samples. It can be concluded that PPE was found to have protective effects on Khalal Barhi date fruit quality by controlling post-harvest changes and lowering the microbial load.

Phenolic Compounds from New Natural Sources-Plant Genotype and Ontogenetic Variation

Phenolic compounds (PCs) are widespread secondary metabolites with potent biological activity. Their sources are mainly plants from cultivated and natural states, providing valuable protective and health-promoting extracts. The wide biological activity of PCs (antioxidant, anti-inflammatory, antimicrobial, antiatherosclerotic, antidiabetic, antiallergic, prebiotic, antimutagenic) means that new sources of PCs are constantly being sought, as exemplified by extracting these compounds from tissue culture or agricultural by-products. Plant phenols show marked qualitative and quantitative variation not only at different genetic levels (between and within species and clones) but also between different physiological and developmental stages. Assessing genetic and seasonal variations in phenolic content and activity allows for selecting the best time to harvest the plant. Learning about the causes of PCs' variability and putting this knowledge into practice can significantly increase PCs' yields and extract the most valuable compounds. The health-promoting properties resulting from consuming products rich in plant PCs are undeniable, so it is worth promoting high-phenolic products as a regular diet. This paper presents an overview of different sources of PCs for use as potential therapeutic alternatives. Additionally, factors of variation in the phenolic complex at the genome and ontogeny levels, relevant in practical terms and as a basis for further scientific research, are presented.

Valorization of Peels of Eight Peach Varieties: GC-MS Profile, Free and Bound Phenolics and Corresponding Biological Activities

Sustainability, becoming essential for food processing and technology, sets goals for the characterization of resources considered as food waste. In this work, information about the GC-MS metabolites of peach peels was provided as a tool that can shed more light on the studied biological activities. In addition, distribution patterns and contribution of the chemical profile and free and bound phenolic compounds as antioxidant, antimicrobial, and enzymatic clusters in peach peels of different varieties of Bulgarian origin were studied. The two applied techniques (alkaline and acid hydrolysis) for releasing the bound phenolics reveal that alkaline hydrolysis is a better extraction approach. Still, the results indicate the prevalence of the free phenolics in the studied peach peel varieties. Total phenolics of peach wastes were positively correlated with their antioxidant activity. The antioxidant activity results certainly defined the need of an individual interpretation for each variety, but the free phenolics fractions could be outlined with the strongest potential. The limited ability of the peels' extracts to inhibit α-amylase and acetylcholinesterase, and the moderate antimicrobial activity, on the other hand, indicate that the potential of peach peels is still sufficient to seek ways to valorize this waste. Indeed, this new information about peach peels can be used to characterize peach fruits from different countries and/or different food processes, as well as to promote the use of this fruit waste in food preparation.