Protein Oxidation in Foods: Mechanisms, Consequences, and Antioxidant Solutions

Unlocking the potential of fishery waste: exploring diverse applications of fish protein hydrolysates in food and nonfood sectors

Fish and their byproducts play a pivotal role as protein sources. With the global population increasing, urbanization on the rise and increased affluence, efficient utilization of available protein resources is becoming increasingly critical. Additionally, the need for sustainable protein sources is gaining recognition. By 2050, the world's protein demand is expected to double, driven not only by population growth but also by heightened awareness of protein's role in maintaining health. The fishery industry has experienced continuous growth over the last decade. However, this growth comes with a significant challenge: inadequate waste management. The fisheries industry discards 35% to 70% of their production as waste, including fillet remains, skin, fins, bones, heads, viscera and scales. Despite the importance of these byproducts as protein sources, their effective utilization remains a hurdle. Various strategies have been proposed to address this issue. Among them, the production of protein hydrolysates stands out as an efficient method for value addition. Protein hydrolysis breaks down proteins into smaller peptides with diverse functional and bioactive properties. Therefore, fish protein hydrolysates have applications in both the food and nonfood sectors. Utilizing fishery byproducts and waste represents a sustainable approach toward waste valorization and resource optimization in the fishery industry. This approach offers promising opportunities for innovation and economic growth across multiple sectors. This comprehensive review explores fish protein hydrolysates derived from fishery byproducts and wastes, focusing on their applications in both the food and nonfood sectors.

Goat Milk Exhibits a Higher Degree of Protein Oxidation and Aggregation than Cow Milk During Cold Storage

Due to their markedly distinct protein compositions and structures, goat milk and cow milk display substantially different characteristics. In this study, the quality and composition of goat milk and cow milk were studied after being refrigerated at 4 °C for 7 days, with a particular focus on protein oxidation and aggregation states. The results revealed that alongside increases in acidity, microbial colony count, and hydrolysis, there was a significant change in the protein aggregation state beginning on the second day. This change was characterized by increased turbidity, an elevated centrifugal sedimentation rate, and a right-shifted particle size distribution. After seven days of refrigeration, the centrifugal sedimentation rate of goat milk increased from 0.53% to 0.97%, whereas that of cow milk rose from 0.41% to 0.58%. The degree of aggregation was significantly greater in goat milk compared to cow milk. Additionally, both protein and lipids exhibited substantial oxidation, with the degree of oxidation more pronounced in goat milk than in cow milk. The malondialdehyde (MDA) content increased from 0.047 μg/mL to 0.241 μg/mL in goat milk and from 0.058 μg/mL to 0.178 μg/mL in cow milk. The results suggest that goat milk was more prone to oxidation, which further reduced its stability. Therefore, in the storage and transportation of dairy products before processing, it is essential not only to monitor sanitary conditions but also to effectively control protein oxidation to enhance the quality of milk processing.

Inhibitory effect of L-arginine on the oxidative aggregation behavior of myofibrillar proteins in the Antarctic krill (Euphausia superba): pH and antioxidation

In this study, the effect of L-arginine (L-Arg) on the oxidative aggregation of myofibrillar proteins (MPs) in Antarctic krill was evaluated. The results showed that the oxidized aggregation of MPs was significantly inhibited after the addition of 20 mM L-Arg compared to the oxidized group, the solubility of MPs significantly increased by 25.74 %, the turbidity reduced from 0.56 to 0.18. These effects were primarily attributed to the addition of L-Arg, which prevented the unfolding of the spatial structure of MPs after oxidation, inhibited the formation of disulfide bonds and dityrosine, and improved the stability of MPs structure. Analysis of carbonyl content and hydroxyl radical (•OH) inhibitory capacity showed that carbonyl formation and hydroxyl radicals were effectively reduced by the pH and guanidinium group of L-Arg. The pH of L-Arg exhibited a significantly higher effect than the guanidinium group in inhibiting the oxidative aggregation of MPs.

Advancements in Biosensors for Lipid Peroxidation and Antioxidant Protection in Food: A Critical Review

This review highlights the progress made in recent years on biosensors aimed at detecting relevant analytes/markers of food peroxidation. Starting from the basic definition of biosensors and the chemical features of peroxidation, here we describe the different approaches that can be used to obtain information about the progress of peroxidation and the efficacy of antioxidants. Aptamers, metal-organic frameworks, nanomaterials, and supported enzymes, in conjunction with electrochemical methods, can provide fast and cost-effective detection of analytes related to peroxidation, like peroxides, aldehydes, and metals. The determination of (poly)phenols concentrations by biosensors, which can be easily obtained by using immobilized enzymes (like laccase), provides an indirect measure of peroxidation. The rationale for developing new biosensors, with a special focus on food applications, is also discussed.

Ultra-processed plant-based analogs: Addressing the challenging journey toward health and safety

Currently, plant-based analogs are presented as healthier alternatives to the products they are intended to replace. However, the processing to which ultra-processed plant-based analogs are subjected to acquire the characteristics of animal-derived products might result in the opposite effect, producing unhealthy ultra-processed foods. In the present review, a list of strategies widely known and already employed in animal-derived products is suggested to achieve healthier, safer, and tastier ultra-processed plant-based analogs: fermentation, employment of probiotics and postbiotics, NaCl replacement or substitution, addition of antioxidants, and fatty profile enhancement. In general, these strategies are not yet applied to the plant-based products available on the market; thus, this research paper might induce new investigation pathways for researchers and producers to develop actually healthier alternatives.

Hydroxyl radical-induced oxidation boosts the gelation of ginkgo seed protein in the presence of hyaluronic acid

Hydroxyl radical-induced oxidation can modify gelling properties of food proteins. In this study, a hydroxyl radical generating system (HRGS), consisting of 0.1 mM Fe3+, 0.1 mM ascorbic acid, and 1, 10, or 20 mM H2O2, was used to oxidize ginkgo seed protein isolate (GSPI) for 4 h at ambient temperature in the presence of 0.3 % (w/v) hyaluronic acid (HA) to enhance its gelation properties. HRGS treatment led to increased protein hydrophobicity, reduced sulfhydryl content, and disulfide bond-mediated protein crosslinking. Moreover, the secondary structure of GSPI varied with H2O2 concentrations. Moderate oxidation (approximately 10 mM H2O2) promoted GSPI aggregation and improved mechanical strength, rheological properties, water holding capacity, and whiteness of GSPI gels. However, excessive oxidation disrupted hydrogen bonding, generated excessive disulfide bonds, hindered active group interaction, inhibited gel network formation, and reduced gel strength. Hence, hydroxyl radical-induced oxidation holds potential for enhancing GSPI gelation within specific concentration ranges. This study suggests that controlled oxidation could be a novel approach for developing protein-based gel products.

Anthocyanin-Loaded Polymers as Promising Nature-Based, Responsive, and Bioactive Materials

Anthocyanins are a specific group of molecules found in nature that have recently received increasing attention due to their interesting biological and colorimetric properties that have been successfully applied in several fields such as food preservation and biomedicine. Consequently, reviews devoted to a general overview of these flavonoids have proliferated in recent years. Meanwhile, the incorporation of anthocyanins into polymeric systems has become an interesting strategy to widen the applicability of these molecules and develop new smart and functional polymers in the above cited areas. However, anthocyanin-based polymers have been scarcely reviewed in the literature. Accordingly, this review aims to be a systematic summary of the most recent approaches for the incorporation of anthocyanins into macro-, micro-, or nanostructured polymers. Moreover, this work describes the fundamentals of the applicability of smart anthocyanin-based polymers and offers an updated review of their most interesting applications as sensors, biological regulators, and active materials.

Protein Hydrolysates from Fishery Processing By-Products: Production, Characteristics, Food Applications, and Challenges

Fish processing by-products such as frames, trimmings, and viscera of commercial fish species are rich in proteins. Thus, they could potentially be an economical source of proteins that may be used to obtain bioactive peptides and functional protein hydrolysates for the food and nutraceutical industries. The structure, composition, and biological activities of peptides and hydrolysates depend on the freshness and the actual composition of the material. Peptides isolated from fishery by-products showed antioxidant activity. Changes in hydrolysis parameters changed the sequence and properties of the peptides and determined their physiological functions. The optimization of the value of such peptides and the production costs must be considered for each particular source of marine by-products and for their specific food applications. This review will discuss the functional properties of fishery by-products prepared using hydrolysis and their potential food applications. It also reviews the structure-activity relationships of the antioxidant activity of peptides as well as challenges to the use of fishery by-products for protein hydrolysate production.

Ultrasonication and microwave pre-treated locust protein hydrolysates enhanced the storage stability of meat emulsion

Locust protein hydrolysates (LoProHs) pre-processed with microwave and ultrasonication were developed and evaluated for their potential for enhancing the quality of the stored meat emulsion (MEmul). Locust protein (LoPro) samples pre-processed with ultrasonication (Ult) or microwave (Mic) or with no treatment (Not) were hydrolysed with alcalase enzyme (3%). The microwave pre-processed (Mic-LoProHs) and ultrasonicated (Ult-LoProHs) hydrolysates showed significantly (P < 0.05) higher antioxidant [FRAP (ferric reducing antioxidant power) and ABTS and DPPH radical scavenging activities] and antimicrobial [minimum inhibitory concentration (MIC) and inhibitory halos (mm)] potential. The MEmul samples incorporated with Mic-LoProHs and Ult-LoProHs at the maximum level of 1.5% exhibited significantly (P < 0.05) improved results for all the quality parameters such as antioxidant potential (FRAP, ABTS and DPPH), protein oxidation (total carbonyl content), lipid stability, and microbial quality during refrigerated storage (4 ± 1 °C) of two-weeks compared to the control MEmul without any LoProHs. A positive (P < 0.05) impact of the LoProHs was found on the sensory quality of MEmul samples after one week of storage. The digestion simulation improved (P < 0.05) the antioxidant potential of the MEmul samples.

Using plant-based compounds as preservatives for meat products: A review

The susceptibility of meat and meat products (MP) to oxidation and microbial deterioration poses a risk to the nutritional quality, safety, and shelf life of the product. This analysis provides a brief overview of how bioactive compounds (BC) impact meat and MP preservation, and how they can be utilized for preservation purposes. The use of BC, particularly plant-based antioxidants, can reduce the rate of auto-oxidation and microbial growth, thereby extending the shelf life of MP. These BC include polyphenols, flavonoids, tannins, terpenes, alkaloids, saponins, and coumarins, which have antioxidant and antimicrobial properties. Bioactive compounds can act as preservatives and improve the sensory and physicochemical properties of MP when added under appropriate conditions and concentrations. However, the inappropriate extraction, concentration, or addition of BC can also lead to undesired effects. Nonetheless, BC have not been associated with chronic-degenerative diseases and are considered safe for human consumption. MP auto-oxidation leads to the generation of reactive oxygen species, biogenic amines, malonaldehyde (MDA), and metmyoglobin oxidation products, which are detrimental to human health. The addition of BC at a concentration ranging from 0.025 to 2.5% (w/w in powdered or v/w in oil or liquid extracts) can act as a preservative, improving color, texture, and shelf life. The combination of BC with other techniques, such as encapsulation and the use of intelligent films, can further extend the shelf life of MP. In the future, it will be necessary to examine the phytochemical profile of plants that have been used in traditional medicine and cooking for generations to determine their feasibility in MP preservation.

Fatty acid and oxidative shelf-life profiles of meat from lambs fed finisher diets containing Acacia mearnsii leaf-meal

Five diets containing Acacia mearnsii leaf-meal (AMLM; 0, 50, 100, 150 and 200 g/kg DM) substituted for Triticum aestivum bran were fed to lambs for 42 days. The effect of diet and retail display period on meat fatty acid (FA) composition (day 1); colour, antioxidant activity, myoglobin and lipid oxidation (day 1, 3, 5, 7 and 9); protein oxidation (1, 3 and 7 d) and instrumental tenderness (day 1, 5 and 10) were evaluated. Dietary AMLM linearly decreased (P ≤ 0.05) individual (14:0, 16:0, 18:0) and total saturated FA and increased (P ≤ 0.05) trans(t)-monounsaturated FA (MUFA) mainly t10/t11-18:1, individual and total conjugated linoleic acids, n-3 and n-6 polyunsaturated FA (PUFA) contents. The contents of cis(c)-MUFA, mainly c9-18:1, exhibited a quadratic response reaching a minimum at 50 g/kg AMLM (P ≤ 0.05). Meat antioxidant on day 9 was higher (P ≤ 0.05) for diets containing ≥100 g/kg DM AMLM compared to the other diet × retail display period interactions. Relative to the other interactions, meat redness values were lowest on day 7 and 9 for AMLM diets containing ≥150 g/kg DM (P ≤ 0.05). Dietary addition of AMLM increased (P ≤ 0.05) meat lightness and oxymyoglobin, and reduced (P ≤ 0.05) TBARS and instrumental tenderness values. However, oxymyoglobin values declined (P ≤ 0.05) over the retail display period, while lightness, metmyoglobin, TBARS and carbonyls increased (P ≤ 0.05). Results indicate that AMLM up to 200 g/kg DM in lamb finisher diets, improves meat fatty acid composition, tenderness, and lipid shelf-life.

Formation of Oxidative Compounds during Enzymatic Hydrolysis of Byproducts of the Seafood Industry

There is a significant potential to increase the sustainability of the fishing and aquaculture industries through the maximization of the processing of byproducts. Enzymatic hydrolysis provides an opportunity to valorize downstream fish industry byproducts for the production of protein hydrolysates (FPH) as a source of bioactive peptides (BAP) with health benefits. Deteriorative oxidative reactions may occur during the enzymatic hydrolysis of byproducts, influencing the safety or bioactivities of the end product. Lipid oxidation, autolysis mediated by endogenous enzymes in viscera, protein degradation, and formation of low-molecular-weight metabolites are the main reactions that are expected to occur during hydrolysis and need to be controlled. These depend on the freshness, proper handling, and the type of byproducts used. Viscera, frames, trimmings, and heads are the byproducts most available for enzymatic hydrolysis. They differ in their composition, and, thus, require standardization of both the hydrolysis procedures and the testing methods for each source. Hydrolysis conditions (e.g., enzyme type and concentration, temperature, and time) also have a significant role in producing FPH with specific structures, stability, and bioactivity. Protein hydrolysates with good safety and quality should have many applications in foods, nutraceuticals, and pharmaceuticals. This review discusses the oxidative reactions during the enzymatic hydrolysis of byproducts from different fish industry sectors and possible ways to reduce oxidation.

Advances in the control of lipid peroxidation in oil-in-water emulsions: kinetic approaches†

Large efforts have been, and still are, devoted to minimize the harmful effects of lipid peroxidation. Much of the early work focused in understanding both the lipid oxidation mechanisms and the action of antioxidants in bulk solution. However, food-grade oils are mostly present in the form of oil-in-water emulsions, bringing up an increasing complexity because of the three-dimensional interfacial region. This review presents an overview of the kinetic approaches employed in controlling the oxidative stability of edible oil-in-water emulsions and of the main outcomes, with particular emphasis on the role of antioxidants and on the kinetics of the inhibition reaction. Application of physical-organic chemistry methods, such as the pseudophase models to investigate antioxidant partitioning, constitute a remarkable example on how kinetic methodologies contribute to model chemical reactivity in multiphasic systems and to rationalize the role of interfaces, opening new opportunities for designing novel antioxidants with tailored properties and new prospects for modulating environmental conditions in attempting to optimize their efficiency. Here we will summarize the main kinetic features of the inhibition reaction and will discuss on the main factors affecting its rate, including the determination of antioxidant efficiencies from kinetic profiles, structure-reactivity relationships, partitioning of antioxidants and concentration effects.