Inhibition of enzymatic browning in actual food systems by the Maillard reaction products

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.

Stability of polyphenols in food processing

In recent years, polyphenols have attracted considerable attention due to their diverse potential health-beneficial effects on humans. Polyphenols are widely distributed in natural plants, and therefore play an important role in human food. Thermal processing, irradiation, fermentation, high pressure, microwave, and drying are several popular food processing methods. However, polyphenols are instable in food processing, which easily degrade and react with other components because of their polyhydroxy characteristic. Traditional and advanced technologies have been used to characterize the stability of polyphenols. The main influence factors of stability of polyphenols such as pH, temperature, light, oxygen, enzymes, metal ions, as well as macromolecules, are summarized. Besides, thermal processing greatly promoted the degradation of polyphenols. Thermal degradation mechanisms and products of some polyphenols, such as quercetin and rutin, have been intensively demonstrated. Nevertheless, the structural changes of polyphenols caused by food processing, may lead to different bioactivities from the obtained results based on unprocessed polyphenols. Therefore, to maximize the beneficial effects of polyphenols ingested by human from processed food, the stability of polyphenols in food processing must be thoroughly investigated to assess their real bioactivities. In addition, some available technologies for improving the stability of polyphenols in food processing have been proposed.

Impact of Drying Processes on the Nutritional Composition, Volatile Profile, Phytochemical Content and Bioactivity of Salicornia ramosissima J. Woods

Salicornia ramosissima J. Woods is a halophyte plant recognized as a promising natural ingredient and will eventually be recognized a salt substitute (NaCl). However, its shelf-life and applicability in several food matrices requires the use of drying processes, which may have an impact on its nutritional and functional value. The objective of this study was to evaluate the effect of oven and freeze-drying processes on the nutritional composition, volatile profile, phytochemical content, and bioactivity of S. ramosissima using several analytical tools (LC-DAD-ESI-MS/MS and SPME-GC-MS) and bioactivity assays (ORAC, HOSC, and ACE inhibition and antiproliferative effect on HT29 cells). Overall, results show that the drying process changes the chemical composition of the plant. When compared to freeze-drying, the oven-drying process had a lower impact on the nutritional composition but the phytochemical content and antioxidant capacity were significantly reduced. Despite this, oven-dried and freeze-dried samples demonstrated similar antiproliferative (17.56 mg/mL and 17.24 mg/mL, respectively) and antihypertensive (24.56 mg/mL and 18.96 mg/mL, respectively) activities. The volatile composition was also affected when comparing fresh and dried plants and between both drying processes: while for the freeze-dried sample, terpenes corresponded to 57% of the total peak area, a decrease to 17% was observed for the oven-dried sample. The oven-dried S. ramosissima was selected to formulate a ketchup and the product formulated with 2.2% (w/w) of the oven-dried plant showed a good consumer acceptance score. These findings support the use of dried S. ramosissima as a promising functional ingredient that can eventually replace the use of salt.

Preliminary Investigation on the Physicochemical and Functional Properties of Commercial Salmorejo Found in Spanish Supermarkets

Salmorejo is a traditional Spanish food made of raw tomatoes, bread, garlic, and virgin olive oil. The food industry aims to satisfy consumer demand for ready-to-eat salmorejo while trying to maintain characteristics of the homemade product. In this work, we have assessed physical-chemical and color parameters, radical scavenging activity, and total polyphenol, lycopene, and β-carotene contents of raw and pasteurized commercial salmorejo, as well as homemade (raw) salmorejo samples. Our results showed that heat treatment had a significant influence on color parameters of salmorejo, with pasteurized samples being less red and exhibiting an increase in the degree of browning. Pasteurized samples also showed the highest radical scavenging activity when expressing the results per dry weight. However, when water content was considered, radical scavenging activity was superior in homemade samples when analyzing non-polar molecules extracted with acetone. Results were similar for polyphenol content. It was also observed that heat treatment affected lycopene but not β-carotene content. When acquiring commercial salmorejo at the supermarket, consumers have the option to choose between already prepared pasteurized or raw salmorejo. According to the results obtained in this work, physicochemical and functional properties of commercial raw salmorejo were comparable to a larger extent than pasteurized salmorejo compared to those exhibited by homemade salmorejo samples.

A model system based on glucose-arginine to monitor the properties of Maillard reaction products

An arginine-glucose mixture (1:2 mol ratio) with pH 9 was heated at 53-100 °C for 10-350 min, and the effects of process parameters were determined during the Maillard reaction (MR). The heating temperature and time were selected as process conditions and were studied with central composite design. The model system was tested based on the values obtained from antioxidant capacity, browning intensity, pH, acrylamide (AC), and hydroxymethylfurfural (HMF) concentrations. Higher temperatures and longer time resulted in higher antioxidant capacity and browning intensity while lowering the pH values. HMF concentration of MR products was found higher in lower temperatures with longer processing time, whereas AC concentration was found higher in high temperatures.

Heated plant extracts as natural inhibitors of enzymatic browning: A case of the Maillard reaction

Enzymatic browning is the second largest cause of quality loss in fruits, vegetables, and seafood. Methods to prevent browning are the subject of great research interest in the field of Food Science and Technology. Numerous strategies for inhibiting enzymatic browning have been proposed in literature. Recent research is focused on finding alternative anti-browning agents to synthetics such as sulfites. Amongst natural antioxidants, Maillard reaction products (MRPs) have proven to be effective. Although reviews have been published on the antioxidant and anti-browning activity of MRPs, none of these focused solely on enzymatic browning inhibition mechanism of MRPs generated via heated plant extracts. Therefore, this review explores the common factors associated with the Maillard reaction (temperature, time, and concentration) and enzymatic browning inhibition (enzyme, substrate and reaction time) in order to confirm the activity and presence of MRPs in heated plant extracts. PRACTICAL APPLICATIONS: Chemical food additives applied in prevention of enzymatic browning are subjected to scrutiny. Therefore, alternative natural compounds are sought after. Plant extracts have been applied, however, they tend to impart their characteristic natural flavor into the product. Heating of these plant extracts have been proven to reduce the "planty, herby" flavors, whilst producing Maillard reaction. Maillard reaction products are known to exhibit anti-browning activity, and they are a cheap alternative to these chemical inhibitors. Therefore, these can be applied as potential anti-browning agents in food products.

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.

Production and stability study of a hospital parenteral nutrition solution for neonates

Standard parenteral nutrition solutions are mixtures comprising interacting components that may degrade themselves over time. The objective of this study was to investigate the physicochemical and microbiological stability of a hospital preparation for parenteral nutrition in neonatology. The analyses were performed throughout the storage of the preparations at 2-8 °C (up to 4 months). The extent of stability was based on the determination of amino acids dosage, visual and physicochemical properties (glucose and electrolytes concentrations, pH and osmolality measurements, particle counting) and microbiological analysis (sterility test). A thermal degradation of ascorbic acid was conducted to evaluate the antioxidant properties of the parenteral mixture. Physicochemical and microbiological controls were found to comply with the specifications. Amino acids showed a good stability throughout the 4months storage except for cysteine, which was progressively degraded to cystine, conferring a yellow coloration to parenteral solutions. Parenteral nutrition standards solutions remain stable for 4 months at 2-8 °C, ensuring safe administration in preterm infants.

Changes in pericarp metabolite profiling of four litchi cultivars during browning

The pericarp browning is an important physiological index during the postharvest storage, which seriously shortens the shelf-life of litchi fruit. In this study, the browning index of four litchi cultivars were compared, and the shelf-life, from longer to shorter, was 'Feizixiao (FXZ)', 'Jingganghongnuo (JGHN)', 'Huaizhi (HZ)' and 'Nuomici (NMC)', respectively. Then, comparative metabolomics were performed in the pericarp of four litchi cultivars during browning. Finding results showed that a total of 119 kinds of metabolites were detected in litchi pericarp, including 30 kinds of primary metabolites, 44 kinds of volatile compounds, 29 kinds of free amino acids and 16 kinds of hydrolytic amino acids. After ANOVA and OPLS-DA, 52 kinds of metabolites were important with predictive VIP > 1 and p < 0.05. In FZX pericarp, the contents of many amino acids increased significantly, which might be related to the yellow-green pericarp and play an important role in delaying browning. In the pericarp of JGHN, NMC and HZ, a great number of soluble sugars and some free amino acids were induced during browning, which was negatively correlated with the browning speed of three red pericarp cultivars. The browning induced a large number of sesquiterpenes in the pericarp of FZX, NMC and HZ, which was positively correlated with the browning index. In addition, the correlation analysis showed that the amino acids were negatively correlated with the volatile compounds, suggesting that pericarp browning could induce the conversion of metabolic products from amino acids to terpenes.

Correlating enzymatic browning inhibition and antioxidant ability of Maillard reaction products derived from different amino acids

BACKGROUND

Up to now, only limited research on enzymatic browning inhibition capacity (BIC) of Maillard reaction products (MRPs) has been reported and there are still no overall and systematic researches on MRPs derived from different amino acids. In the present study, BIC and antioxidant capacity, including 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and Fe²⁺ reducing power activity, of the MRPs derived from 12 different amino acids and three reducing sugars were investigated.

RESULTS

The MRPs of cysteine (Cys), cystine, arginine (Arg) and histidine (His) showed higher BIC compared to other amino acids. Lysine (Lys)-MRPs showed the highest absorbance value at 420 nm (A₄₂₀ ) but very limited BIC, whereas Cys-MRPs, showed the highest BIC and the lowest A₄₂₀ . The A₄₂₀ can roughly reflect the trend of BIC of MRPs from different amino acids, except Cys and Lys. MRPs from tyrosine (Tyr) showed the most potent antioxidant capacity but very limited BIC, whereas Cys-MRPs showed both higher antioxidant capacity and BIC compared to other amino acids. Partial least squares regression analysis showed positive and significant correlation between BIC and Fe²⁺ reducing power of MRPs from 12 amino acids with glucose or fructose, except Lys, Cys and Tyr. The suitable pH for generating efficient browning inhibition compounds varies depending on different amino acids: acidic pH was favorable for Cys, whereas neutral and alkaline pH were suitable for His and Arg, respectively. Increasing both heating temperature and time over a certain range could improve the BIC of MRPs of Cys, His and Arg, whereas any further increase deteriorates their browning inhibition efficiencies.

CONCLUSION

The types of amino acid, initial pH, temperature and time of the Maillard reaction were found to greatly influence the BIC and antioxidant capacity of the resulting MRPs. There is no clear relationship between BIC and the antioxidant capacity of MRPs when reactant type and processing parameters of the Maillard reaction are considered as variables. © 2017 Society of Chemical Industry.

State of polyphenols in the drying process of fruits and vegetables

This review presents an overview of drying technologies and its impact on the polyphenol content of vegetables and fruits. Polyphenols contribute to many health benefits and can act as antioxidants. Specifically an increased intake of polyphenols has been shown to decrease the incidence of cardiovascular disease; furthermore, it has been shown to help reduce the risk of neurodegenerative diseases in humans. Many researchers have reported on the effect of different drying techniques on the polyphenol content in fruits and vegetables. Polyphenol degradation mechanisms proposed in literature and pretreatments that potentially lead to higher retention of polyphenols during drying are also discussed.

Inhibition effects of Maillard reaction products derived from l-cysteine and glucose on enzymatic browning catalyzed by mushroom tyrosinase and characterization of active compounds by partial least squares regression analysis

Inhibition of tyrosinase activity by Maillard reaction products derived from cysteine and glucose (Cys-MRPs) was studied.

The Maillard reaction and pet food processing: effects on nutritive value and pet health

The Maillard reaction, which can occur during heat processing of pet foods or ingredients, is known to reduce the bioavailability of essential amino acids such as lysine due to the formation of early and advanced Maillard reaction products (MRP) that are unavailable for utilisation by the body. Determination of the difference between total and reactive lysine by chemical methods provides an indication of the amount of early MRP present in foods, feeds and ingredients. Previous research reported that the difference between total and reactive lysine in pet foods can be up to 61.8%, and foods for growing dogs may be at risk of supplying less lysine than the animal may require. The endogenous analogues of advanced MRP, advanced glycation endproducts, have been associated with age-related diseases in humans, such as diabetes and impaired renal function. It is unknown to what extent advanced MRP are present in pet foods, and if dietary MRP can be associated with the development of diseases such as diabetes and impaired renal function in pet animals. Avoidance of ingredients with high levels of MRP and processing conditions known to favour the Maillard reaction may be useful strategies to prevent the formation of MRP in manufactured pet food. Future work should further focus on understanding the effects of ingredient choice and processing conditions on the formation of early and advanced MRP, and possible effects on animal health.