Antioxidant and antibrowning properties of Maillard reaction products in food and biological systems.

Oxidative damage refers to the harm caused to biological systems by reactive oxygen species such as free radicals. This damage can contribute to a range of diseases and aging processes in organisms. Moreover, oxidative deterioration of lipids is a serious problem because it reduces the shelf life of food products, degrades their nutritional value, and produces reaction products that could be toxic. Antioxidants are effective compounds for preventing lipid oxidation, and synthetic antioxidants are frequently added to foods due to their high effectiveness and low cost. However, the safety of these antioxidants is a subject that is being discussed in the public more and more. Synthetic antioxidants have been found to have potential negative effects on health due to their ability to accumulate in tissues and disrupt natural antioxidant systems. During thermal processing and storage, foods containing reducing sugars and amino compounds frequently produce Maillard reaction products (MRPs). Through the chelation of metal ions, scavenging of reactive oxygen species, destruction of hydrogen peroxide, and suppression of radical chain reaction, MRPs exhibit excellent antioxidant properties in a variety of food products and biological systems. Also, the capacity of MRPs to chelate metals makes them as a potential inhibitor of the enzymatic browning in fruits and vegetables. In this book chapter, the methods used for the evaluation of antioxidant activity of MRPs are provided. Moreover, the antioxidant and antibrowning activities of MRPs in food and biological systems is discussed. MRPs can generally be isolated and used as commercial preparations of natural antioxidants.

Bioactive foamulsion gels: a unique structure prepared with gellan gum and Acanthophyllum glandulosum extract.

BACKGROUND: Foamulsions have become increasingly popular in the food industry due to their ability to enhance the textural, sensory and health-promoting properties of food products. This study was therefore aimed to design and prepare a novel gelled structure, foamulsion gel containing 0-600 g L-1 oil, with gellan gum (GG; 7, 10 and 13 g L-1) and saponin-rich antioxidant Acanthophyllum glandulosum extract (AGE; 2, 6 and 10 g L-1). RESULTS: The interaction between components was confirmed by infrared spectroscopy. The overrun and porosity of the foamulsion gels increased with antioxidant AGE (1.30 times) and reduced with oil (up to ca 70% and 30%, respectively) and GG levels. The systems were highly stable, and no water or oil was released during the physical stability experiments. Microscopic images showed that the size of air cells was significantly larger than that of oil droplets. The foamulsion gels based on 13 g L-1 GG and 10 g L-1 AGE had markedly higher elastic (G') and viscous (G'') moduli than other samples, and exhibited an elastic and solid-like behavior (G' > G''). The highest gel firmness was found in oil-free sample, and the presence of oil resulted in a lower firmness induced by the larger size and lubrication effect of oil droplets. CONCLUSION: As a result, the interactions between AGE, GG and oil could lead to the creation of new aerated structures known as bioactive foamulsion gels. These gels exhibit excellent foamability, stability and viscoelasticity and may find applications in the development of novel, healthy and low-calorie aerated foods. © 2024 Society of Chemical Industry.

Hydro- and aerogels from quince seed gum and gelatin solutions.

The composite hydro/aerogels were designed using gelatin and quince seed gum (QSG) at total polymer concentration (TPC) of 1, 1.5 and 2% and gelatin/QSG ratio of 1:0, 1:0.5 and 1:1. The gel syneresis decreased significantly with increase in TPC and QSG. Although, hydrogels with 2% TPC had remarkably higher gel strength and elasticity than 1% TPC ones, the addition of high levels of QSG to the gelatin (i.e., gelatin/QSG 1:1) led to a decrease in its gel strength (∼0.97-fold) and elasticity (∼3,463-fold). The temperature-sweep test showed higher melting points in gelatin/QSG hydrogels (>60 °C) compared to the gelatin ones (∼58 °C). Additionally, QSG addition to the gelatin led to more porous networks with higher gel strength, thermal stability, and crystallinity, as observed by scanning electron microscopy, differential scanning calorimetry, and X-ray diffractometer. Therefore, QSG could be used as a natural hydrocolloid to modify gelatin functionality.

Green leaf proteins: a sustainable source of edible plant-based proteins.

The rise in the global population, which is projected to reach 9.7 billion by 2050, has resulted in an increased demand for proteins in the human diet. The green leaves of many plants are an affordable, abundant, and sustainable source of proteins suitable for human consumption. This article reviews the various sources of green leaf proteins that may play an important role in alleviating global malnutrition, including those from alfalfa, amaranth, cabbage, cassava, duckweed, moringa, olive, radish, spinach, sugar beet, and tea. The structure of green leaves and the location of the proteins within these leaves are described, as well as methods for extracting and purifying these proteins. The composition, nutritional profile, and functional attributes of green leaf proteins are then discussed. The potential advantages and disadvantages of using green leaf proteins as functional food ingredients are highlighted. The importance of obtaining a better understanding of the composition and structure of different green leaves and the proteins extracted from them is highlighted. This includes an assessment of non-protein nitrogen and anti-nutritional compounds that may be present. Furthermore, the impact of isolation and purification techniques on the functionality of the plant protein ingredients obtained must be carefully evaluated.

Behavior of protein-polysaccharide conjugate-stabilized food emulsions under various destabilization conditions.

The sensitivity of protein-stabilized emulsions to flocculation, coalescence, and phase separation under destabilization conditions (i.e., heating, aging, pH, ionic strength, and freeze-thawing) may limit the widespread use of proteins as effective emulsifiers. Therefore, there is a great interest in modulating and improving the technological functionality of food proteins by conjugating them with polysaccharides, through the Maillard reaction. The present review article highlights the current approaches of protein-polysaccharide conjugate formation, their interfacial properties, and the behavior of protein-polysaccharide conjugate stabilized emulsions under various destabilization conditions, including long-term storage, heating and freeze-thawing treatments, acidic conditions, high ionic strength, and oxidation. Protein-polysaccharide conjugates are capable of forming a thick and cohesive macromolecular layer around oil droplets in food emulsions and stabilizing them against flocculation and coalescence under unfavorable conditions, through steric and electrostatic repulsion. The protein-polysaccharide conjugates could be therefore industrially used to design emulsion-based functional foods with high physicochemical stability.

Recent advances in qualitative and quantitative characterization of nanocellulose-reinforced nanocomposites: A review.

Nanocellulose has received immense consideration owing to its valuable inherent traits and impressive physicochemical properties such as biocompatibility, thermal stability, non-toxicity, and tunable surface chemistry. These features have inspired researchers to deploy nanocellulose as nanoscale reinforcement materials for bio-based polymers. A simple yet efficient characterization method is often required to gain insights into the effectiveness of various types of nanocellulose. Despite a decade of continuous research and booming growth in scientific publications, nanocellulose research lacks a measuring tool that can characterize its features with acceptable speed and reliability. Implementing reliable characterization techniques is critical to monitor the specifications of nanocellulose alone or in the final product. Many techniques have been developed aiming to measure the nano-reinforcement mechanisms of nanocellulose in polymer composites. This review gives a full account of the scientific underpinnings of techniques that can characterize the shape and arrangement of nanocellulose. This review aims to deliver consolidated details on the properties and characteristics of nanocellulose in biopolymer composite materials to improve various structural, mechanical, barrier and thermal properties. We also present a comprehensive description of the safety features of nanocellulose before and after being loaded within biopolymeric matrices.

Changes in fat uptake, color, texture, and sensory properties of Aloe vera gel-coated eggplant rings during deep-fat frying process.

There is a widespread use of deep-fat frying in both domestic and industrial sections, and deep-fat fried foods are extremely popular due to their taste, color, and crispy texture. Human health can be, however, seriously compromised by the excessive consumption of oil, especially saturated fats and trans fatty acids. The use of hydrocolloids in inhibiting oil absorption has garnered considerable attention. This study was therefore aimed to lower the oil absorption in eggplant rings during the deep-fat frying process with the aid of Aloe vera gel coating. The effects of gel concentration (0%, 50%, and 100%), frying time (2, 5, and 8 min), and frying temperature (160°C and 180°C) on the oil uptake, moisture content, texture, color, and sensory properties of the eggplant rings were evaluated. The gel coating led to a decrease in oil uptake (up to 50%), hardness (up to 0.98-fold), ΔE (up to 0.89-fold), and overall acceptance (up to 0.85-fold), and an increase in moisture content (up to 1.47-fold) and lightness (up to 1.14-fold) of the samples. The frying time and temperature also influenced the physiochemical and sensory properties of the eggplant rings. The sample coated with 50% gel and fried at 180°C for 8 min had lower oil content and water loss with the highest acceptance rate in terms of taste, color, odor, texture, and appearance. The Aloe vera gel could be, therefore, a good candidate with high nutritional and economic value to reduce oil uptake in fried food products.

Gellan gum conjugation with soy protein via Maillard-driven molecular interactions and subsequent clustering lead to conjugates with tuned technological functionality.

Soy proteins are frequently used in the food industry; however, they have rigid and compact structure with relatively poor interfacial properties and solubility. This study was therefore aimed to modify techno-functional characteristics of soy protein isolate (SPI; 0.1% w/v) by conjugating to low acyl gellan gum (LAGG; 0.1, 0.2, and 0.3% w/v), through the Maillard reaction (at 90 °C for 90 min). The SPI-LAGG conjugates were confirmed by changes in pH, glycation degree (DG; up to 48%), Fourier transform infrared spectroscopy, and sodium dodecyl sulphate polyacrylamide electrophoresis. The conjugates were then classified into three clusters of low, medium, and high DG, via K-means clustering method. The low DG conjugate had lower surface hydrophobicity and foaming capacity, and higher thermal stability, solubility, emulsifying properties, foam stability, and antioxidant activity compared to the other clusters. This indicated that a low DG is required to enhance the functional properties of proteins.

Quinoa flour as a skim milk powder replacer in concentrated yogurts: Effect on their physicochemical, technological, and sensory properties.

Milk standardization with solids (i.e., nonfat milk solids, MSNF) for yogurt manufacture is traditionally achieved by the addition of skim milk powder (SMP). However, the addition of SMP to milk-based yogurt increases lactose content and decreases both protein content and gel firmness. Thus, in this work, quinoa flour (QF; 0%, 25%, 50%, 75%, and 100% w/w) was used to replace SMP in concentrated yogurt. The physicochemical, textural, and sensory properties and microstructure of the yogurt were evaluated during cold storage. Generally, protein content, water-holding capacity, and L* value decreased, while syneresis, textural attributes, and viscosity increased with increasing QF content. The substitution of high levels of QF (>25%, w/w) for SMP led to significantly shorter fermentation times, as compared to the control sample. The scanning electron microscopy observations showed significant changes in the yogurt microstructure as a consequence of QF replacement. Samples with 25% (w/w) substitution of QF and control had the highest scores in overall acceptance. According to the results, QF could be applied as an interesting raw material for concentrating the milk-based yogurt at substitution level of 25% (w/w).

Physicochemical stability and gastrointestinal fate of ß-carotene-loaded oil-in-water emulsions stabilized by whey protein isolate-low acyl gellan gum conjugates.

This study aimed to examine the effect of whey protein isolate-low acyl gellan gum (WPI-GG) conjugate on the physicochemical properties and digestibility of ß-carotene-loaded oil-in-water emulsions. The WPI-GG conjugate-stabilized emulsions had lower droplet sizes with more homogenous distribution, more negative surface charge, and higher interfacial protein concentration and viscosity, compared to those stabilized by WPI-GG mixture and WPI. The emulsion droplets coated by the conjugate were also generally more stable to environmental stresses (i.e., storage, pH changes, ionic strength, freeze-thaw cycles, and thermal treatment) along with higher ß-carotene retention than other systems. The stability to droplet aggregation during in vitro digestion was remarkably increased for the conjugate-stabilized emulsion. However, the ß-carotene bioaccessibility was significantly affected when the conjugate was used to stabilize the emulsions, likely due to the thick interfacial layer, high viscosity, and negative charge of the corresponding emulsions that could inhibit droplet digestion and mixed micelle formation.

Functional and biological properties of Maillard conjugates and their potential application in medical and food: A review.

Protein and peptides are usually sensitive to environmental stresses, such as pH changes, high temperature, ionic strength, and digestive enzymes amongst other, which limit their food and medicinal applications. Maillard reaction (also called Maillard conjugation or glycation) occurs naturally without the addition of chemical agents and has been vastly applied to boost protein/peptide/amino acid functionalities and biological properties. Protein/peptide-saccharide conjugates are currently used as emulsifiers, antioxidants, antimicrobials, gelling agents, and anti-browning compounds in food model systems and products. The conjugates also possess the excellent stabilizing ability as a potent delivery system to enhance the stability and bioaccessibility of many bioactive compounds. Carbonyl scavengers such as polyphenols are able to significantly inhibit the formation of advanced glycation end products without a significant effect on early Maillard reaction products (MRPs) and melanoidins, which are currently applied as functional ingredients. This review paper highlights the technological functionality and biological properties of glycoconjugates in food model systems and products. Recent applications of MRPs in medical sciences are also presented.

Antioxidant potential and antimicrobial activity of chitosan-inulin conjugates obtained through the Maillard reaction.

Chitosan (1%) was glycated with inulin (0.5, 1, and 2%) via the Maillard reaction at various initial pH values (5, 5.5, and 6). Higher pHs led to a greater pH drop and increase in the intermediate products and browning intensity (BI). The chitosan-inulin conjugates were then classified into three levels of low, medium, and high BI through K-means clustering in order to investigate the effect of BI development on the antioxidant and antimicrobial attributes of the conjugates. Covalent linkage between chitosan and inulin was confirmed by fourier transform infrared spectroscopy. High BI chitosan-inulin conjugate had significantly higher antioxidant property compared to chitosan and other conjugate fractions. In addition, the conjugates obtained at low pH values mainly presented greater antimicrobial activities than those prepared at high pHs. It can be concluded that chitosan-inulin Maillard-born conjugates can be used as novel antioxidant and antimicrobial prebiotic-based ingredients for food applications.

The Maillard reaction products as food-born antioxidant and antibrowning agents in model and real food systems.

Food products containing lipids, especially unsaturated fatty acids, are prone to oxidation reactions, which lead to the formation of off-flavor, due to side-reaction products that potentially have toxic effects and reduce shelf-life. The Maillard reaction products (MRPs) are widely produced in foods containing reducing sugars and amino-bearing compounds during thermal processing and storage. MRPs possess excellent antioxidant ability in many food products, through chelation of metal ions, breakdown of radical chains and hydrogen peroxide, and scavenging of reactive oxygen species. This review presents an overview of the antioxidant activity of MRPs in model and real food systems. It also provides the pros and cons of the Maillard reaction, some available antioxidant assays to evaluate the antioxidative ability of MRPs, and parameters influencing their functional properties. In addition, metal chelation-based antibrowning ability of MRPs to inhibit the enzymatic browning reaction in fruits and vegetables is discussed.

Microwave-assisted isomerisation of lactose to lactulose and Maillard conjugation of lactulose and lactose with whey proteins and peptides.

Lactose was isomerised to lactulose by microwave heating and purified by a methanolic procedure to a product with approximately 72% lactulose content. Afterwards, lactose and the lactulose-rich product (PLu) were conjugated with either whey protein isolate (WPI) or its antioxidant hydrolysate (WPH) through microwaving. Lactose had a higher Maillard reactivity than PLu, and WPH was more reactive than WPI. The browning intensity of WPI-sugar systems was however higher than that of WPH-sugar pairs. Atomic force microscopy showed larger (up to ≈103 nm) particles for WPI-PLu conjugates compared to WPH-PLu counterparts (up to ≈39 nm). The Maillard conjugation progressively increased the radical-scavenging activity of WPI/WPH-sugar pairs with increasing conjugation time and improved the foaming properties of WPI and WPH. The WPI/WPH-sugar conjugates showed higher solubility and emulsification index than unreacted counterpart pairs. For native WPI, ß-lactoglobulin was not degraded by in vitro gastric digestion, whereas for WPH-PLu conjugates degraded completely.

Maillard conjugation of lactulose with potentially bioactive peptides.

Milk ultrafiltration permeate was heated at 97 °C in the presence of eggshell for 60 min. This decreased the ash content of permeate and converted ≈ 17% of lactose to lactulose. The isomerized permeate was subsequently purified to a lactulose-rich product (LRP; ≈ 70% lactulose content to total sugar) through crystallizing lactose out by methanol. The LRP and lactose were then conjugated with either whey protein isolate (WPI) or its antioxidant hydrolysate (WPH) through Maillard reaction at 90 °C. The amount of the Maillard reaction advanced products was higher for WPI-lactose system than WPH-lactose counterpart; whilst, the DPPH scavenging activities of WPH-sugar conjugates were significantly higher than those of WPI-sugar counterparts. Based on free amino groups content measurement, it was found that lactose is more reactive than LRP for Maillard conjugation with both WPI and WPH. Fourier transform infrared spectroscopy confirmed the bonding of the anomeric region of saccharide configuration of lactulose with WPH.