Non-enzymatic Browning Reactions Research Articles

Antimicrobial and antioxidant capacity of glucosamine-zinc(II) complex via non-enzymatic browning reaction.

Coordination compounds play an important role in the life process, and have been widely used in food, cosmetics and pharmaceutical industry. Herein, we have developed a novel kind of glucosamine-zinc(II) complex (GlcN-ZC) for food additive using non-enzymatic browning reaction. The GlcN-ZC was characterized by FTIR and XRD. Moreover, UV absorbance changes, browning intensity, fluorescence changes, antioxidant activity and antimicrobial assessment of GlcN-ZC were also evaluated. Results showed the GlcN-ZC intermediate compounds were accumulated in non-enzymatic browning while prolonging heating time and melanoidins were produced in the final stage. The fluorescence changes confirmed that fluorophores were formed during the non-enzymatic reaction and fluorescence intensity reached a maximun at 60 min. The highest radical scavenging activity of GlcN-ZC formed after 180min of heating was 79.2%. Furthermore, GlcN-ZC exhibited excellent antibacterial activity against E. coli and S. aureus. Therefore, GlcN-ZC can be used as a novel promising additive in the food industry.

The browning kinetics of the non-enzymatic browning reaction in L-ascorbic acid/basic amino acid systems

Abstract Under the conditions of weak basis and the reaction temperature range of 110-150 °C, lysine, arginine and histidine were reacted with L-ascorbic acid at equal amount for 30-150 min, respectively and the formation of browning products was monitored with UV–vis spectrometry. The kinetic characteristics of their non-enzymatic browning reaction were investigated. The study results indicated that the non-enzymatic browning reaction of these three amino acids with L-ascorbic acid to form browning products was zero-order reaction. The apparent activation energies for the formation of browning products from L-ascorbic acid/lysine, L-ascorbic acid/arginine and L-ascorbic acid/histidine systems were 54.94, 50.08 and 35.31kJ/mol. The activation energy data indicated the degree of effects of reaction temperature on non-enzymatic browning reaction. Within the temperature range of 110-150 °C, the reaction rate of L-ascorbic acid/lysine system was the fastest one, followed by that of the L-ascorbic acid/arginine system. The reaction rate of L-ascorbic acid/histidine system was the slowest one. Based on the observed kinetic data, the formation mechanisms of browning products were proposed.

Possible consequences of the sucrose replacement by a fructose-glucose syrup

The fructose-glucose syrup is currently used instead of sucrose in bakery products for economic and technological reasons. The authors investigated the extent to which this change affects the formation of non-enzymatic browning products (Advanced Glycation End - AGE-Products and melanoidins). Formation of these products in model systems - mixtures of various sugars (sucrose, fructose, glucose - concentration 6%) with glycine (concentration 0.7%) or/and lysine (concentration 0.3%), heat-treated 60 - 100 °C for 15, 30, 45 and 60 min, was studied. The formation of AGE products and melanoidins was determined on the basis of absorption at 294 nm (AGE-products) and 420 nm (melanoidins), respectively. The results pointed out notable difference in the AGE-products and also melanoidins formation for a variety of sugars. The reactivity of sucrose was low even at 100 °C/60 min. Fructose and glucose originated a significantly increasing of the non-enzymatic browning products formation. The reactivity of fructose was in the caramelisation and also in Maillard reactions the highest in any combination of composition. Lysine is the most reactive amino acid which takes part in Maillard reactions even if it is bound to protein. The non-enzymatic browning reactions result in the formation of non-digestible cross-linked proteins. Lysine is also the limiting essential amino acid of most cereals. Due to the lysine properties, reduction in protein quality is the most important nutritional effect of Maillard reactions in food. The sucrose replacement by fructose-glucose syrup in bakery products leads to more extensive non-enzymatic browning reactions, i.e. caramelisation and also Maillard reactions, while changes are in the Maillard reaction more pronounced.

Research on the nonenzymatic browning reactions in model systems based on apple slices dried by instant controlled pressure drop drying

ABSTRACTIn this study, the influences of reducing sugar, amino acids, ascorbic acids, and phenolic compounds on the nonenzymatic browning reactions in model systems based on apple slices were studied. The browning components in apple slices were removed using water and ethanol sequently, and then infiltrated with different solutions. The browning ratio (BR) of apple slice model measured by a computer vision-based image analysis system was used to evaluate the nonenzymatic browning reactions. Compared to the solution containing reducing sugar and amino acids alone, the results showed that the reducing sugar and amino acid solution with the addition of (+)-catechin, L-epicatechin, and phlorizin resulted in a remarkable increment of BR in the apple slices. L-lysine, L-arginine, and L-cysteine showed higher positive effects on the formation of BR in models based on apple slices. This study was contributed to better understand the chemical reaction in real dehydrated apple slices.

Influence of l-pyroglutamic acid on the color formation process of non-enzymatic browning reactions

Heating aqueous d-glucose model reactions with l-glutamine and l-alanine yielded similar colored solutions. However, size-exclusion chromatography (SEC) revealed that both non-enzymatic browning reactions proceeded differently. Due to a fast occurring cyclization of l-glutamine to pyroglutamic acid, the typical amino-carbonyl reaction was slowed down. However, l-glutamine and l-alanine model reactions showed the same browning index. Closer investigations could prove that l-pyroglutamic acid was able to influence non-enzymatic browning reactions. SEC analyses of d-glucose model reactions with and without l-pyroglutamic acid revealed an increase of low molecular colored compounds in the presence of l-pyroglutamic acid. Polarimetric measurements showed a doubling of d-glucose mutarotation velocity and HPLC analyses of d-fructose formation during thermal treatment indicated a tripling of aldose-ketose transformation in the presence of l-pyroglutamic acid, which are signs of a faster proceeding non-enzymatic browning process. 2-Pyrrolidone showed no such behavior, thus the additional carboxylic group should be responsible for the observed effects.

Effects of different drying methods on the physicochemical properties of pomegranate leather (pestil)

The present study examines the effects of various formulations (traditional and hydrocolloid) and drying techniques [hot air drying at 50, 60 or 70 °C, microwave-assisted hot air drying (90 or 180 W) at 50, 60 or 70 °C and refractance window drying 90, 95 and 98 °C), in order to develop new methods for pomegranate pestil production. Water activity, pH, color, textural properties, total phenolic content, total flavonoids, total proantocyanidins, total monomeric anthocyanin, ascorbic acid, HMF content, antioxidant activity, phenolic and anthocyanin profiles and volatile compounds of the pestils were determined. Hydrocolloid formulation resulted in superior physicochemical properties of the pestils compared to traditional formulation. While microwave-assisted drying (MWD) provided higher phenolic content, refractance window (RW) drying provided higher ascorbic acid and anthocyanin content, and lower content of 5-hydroxymethylfurfural. Volatile compounds in the pestils showed that MWD promoted non-enzymatic browning reactions. Overall, the hydrocolloid formulation and the RW drying technique are the most promising processing methods for high-quality pestil production with high content of bioactive compounds.

열처리 조리방법이 마늘의 항산화 활성과 이화학적 특성에 미치는 영향

한국인이 마늘을 섭취할 때 주로 사용하는 조리방법으로 8종의 마늘을 준비하여 조리 조건이 마늘의 항산화 활성과 이화학적 특성에 미치는 영향을 살펴보았다. 열처리 강도가 높은 조리법일수록 마늘의 수분 손실이 컸으며, 명도는 낮아지고 황색도는 높아지는 전형적 갈변 현상을 나타내었다. 특히 명도가 가장 낮았던 프라잉과 팬 프라잉으로 조리된 마늘에서는 수용성 고형분 함량 역시 유의적으로 낮아 조리온도가 높을수록 수용성 저분자 물질로부터 불용성 고분자 중합물질을 형성하는 비효소적 갈변반응이 더 가속화되었음을 시사해주었다. 한편 조리된 마늘은 생마늘보다 thiosulfinates 함량이 낮았으며, 이는 열처리에 의해 thiosulfinates가 polysulfides로 분해되었거나, 열전달 매체를 사용한 삶기, 프라잉, 팬 프라잉으로 조리된 마늘에서는 이들 물질이 열전달 매체로 용출되었을 가능성을 시사해주었다. 전자레인지로 조리된 마늘은 다른 마늘보다 유기산과 thiosulfinates, 플라보노이드 성분들이 상대적으로 많이 보유되어 있었으며, 이는 에너지가 낮고 조리시간이 짧은 전자레인지 가열방식에 의해 마늘 속 열에 약한 성분들이 상대적으로 덜 분해된 결과로 볼 수 있다. 높은 온도에서 조리된 마늘들은 총 환원력과 금속 소거능이 높은 경향을 나타내었으며, 이는 색도 결과에 의해 시사된 것과 같이 환원력을 지닌 갈변반응의 중간물질과 최종물질들이 고온 조리 시 더 활발히 생성된 결과로 해석되었다. 물과 기름을 열전달 매체로 하여 조리된 마늘에서는 총 환원력과 플라보노이드 함량이 상대적으로 낮은 경향을 나타내었다. 그러나 생마늘과 조리된 마늘에서 측정된 총 환원력과 플라보노이드 정량 결과는 DPPH 라디칼 소거능 결과와는 다소 일치하지 않았다. 이는 환원성 물질들의 총량이 증가하였음에도 불구하고 우수한 항산화 활성을 지닌 일부 열에 불안정한 플라보노이드와 페놀 화합물들이 조리 중 감소하였을 가능성을 말해준다. 따라서 조리 중 마늘 내부에서 분해 혹은 새로이 생성될 수 있는 개별 환원성 물질들의 조성과 항산화 활성 비교에 대한 후속연구가 필요할 것으로 생각한다.

Kinetics of non-enzymatic browning reaction from the l-ascorbic acid/l-cysteine model system

The kinetics of the non-enzymatic browning reaction from l-ascorbic acid/l-cysteine model systems was investigated at 125–155°C for 10–120 min by measuring the loss of reactants and monitoring the brown colour development. The result showed that the browning products were produced at the first order reaction kinetics requirement, with the E<sub>a</sub> being 114.33 kJ/mol. The mechanism for the browning development was proposed. The correlation coefficient between browning products and uncoloured intermediate products increased with the rising temperature. At temperatures below 110°C, the non-enzymatic browning reaction did not occur at all or the reaction was slow. Browning products could not be produced solely by self-degradation of l-cysteine. The amount of browning products negatively correlated with the l-ascorbic acid concentration.

Relationship between HMF intake and SMF formation in vivo: An animal and human study.

5-Hydroxymethylfurfural (HMF) is a furanic compound produced in heat-processed foods by nonenzymatic browning reactions. HMF has been demonstrated to be hepato- and nephrotoxic in animals with a link to its metabolite 5-sulfooxymethylfurfural (SMF). To date little is known about either the formation of SMF from ingested HMF or the formation of DNA adducts in animals or human beings. To assess SMF in vivo formation, we first performed a study in mice treated with high/low doses of oral HMF. We found increased concentrations of SMF in plasma and DNA SMF-adducts in leukocytes, hepatic tissue, and kidneys by means of LC-MS/MS, but no spatial formation in such tissues was observed by MALDI-MS imaging technology due to low sensitivity. In a second experiment, we measured the exposure to HMF in a Spanish preadolescent population. We analyzed the concentration of HMF metabolites (plasma, urine) and measured, for the first time, the presence of SMF in plasma and DNA SMF-adducts in leukocytes. This study provides the first evidence that oral HMF is readily transformed into SMF in vivo, giving rise to the formation of DNA adducts in a direct relation with HMF intake, both in animals and human beings.

Interactions of Bio-macromolecules During Processing of Instant Asian Noodles: A Review

The review focuses on how the protein, fats, carbohydrates and water interact and form the complexes during different stages of processing of instant noodles. Moisture is needed for dough formation and chemical interactions therein. Appropriate moisture content is required for proper gelatinization of noodle strand during steaming and eventually moisture is evaporatedoff by drying and frying to increase its shelf life. Frying oil may undergo degradation process invited by high frying time and temperature, high moisture in oil and polyvalent metals. Various intermediate products like dimers and polymers accelerate the oil degradation finally changing the physiochemical properties of oil rendering it unacceptable for processing. Gliadinand glutenin gives noodle its viscoelastic character. The polymeric glutenin network develops throughout the process of mixing, resting and subsequent stages of sheeting. Protein content and amylose content in noodle are inversely proportional to the oil uptake ratio. Another possibility is the non-enzymatic browning reaction during frying of instant noodles.

Quality assessment of dried okara as a source of production of gluten-free flour.

Okara is a by-product of soymilk and of tofu elaboration that is rich in protein, fiber and vegetable oils as a source of gluten-free flour. In order to take advantage of the nutritional characteristics of okara and to be able to determine an appropriate drying methodology, microwave, rotary dryer and freeze-drying were assessed. Furthermore, flour with an enzymatic treatment was characterized as well as its functional, physicochemical, and textural properties. The results showed that the physiochemical characteristics of the flour were affected by the drying process, reaching adequate water content, and high protein and fiber content. The freeze-drying process produced clearer flours with porous structure and high water absorption capacity, and with a higher protein denaturation. Okara dried by microwave and rotary dryer exhibited a denser structure with similar functional properties and improved textural characteristics such as firmness and consistency. The microwave-produced flour was darker due to the non-enzymatic browning reactions. The enzymatic treatment employed improved the consistency of the flour. It was possible to choose the drying process to be applied according to the feasible use of the flour, intended to preserve the favorable nutritional aspects of the okara flour. Based on the results, it can be affirmed that the physicochemical properties and attributes of okara are influenced by the drying process employed. Okara dried by freeze-drying resulted in a better product because it had a low final moisture content and the highest whiteness index. The flour presented a porous structure with high solubility, which is an indicator of potential applications in foods developments. © 2016 Society of Chemical Industry.

Conditions for producing long shelf life fruit salads processed using mild pasteurization

The development of a fruit salad using mild processing conditions is demand to fulfill consumers’ requirements for convenience, long-lasting and healthy foods ensuring safety but preserving the properties of a fresh product. This work intended to investigate the effect of mild-pasteurization and storage temperature on two distinct fruit salads, with different pH (Orange-based fruit salad pH 4.2 and Pear-based fruit salad pH 3.9), to identify the conditions favorable to develop a long shelf life fruit salad. The fruit salads were pasteurized at mild-temperature (70 or 80 °C) and stored at 4 or 25 °C over a period of 98 days. These pasteurization treatments ensured enzymatic inactivation and food safety. However, fruit combination influences fruit salads stability during storage, being colour the most affected parameter due to non-enzymatic browning reactions. Acidity of the fruit salad is important to inhibit oxidation reactions and extend shelf life, as well as the total soluble solids that seem to diminish oxidation process and loss of ascorbic acid. Thus, using mild-pasteurization it is possible to develop fruit salads with shelf life up 2 months stored at room temperature, reducing costs, by simply controlling fruit combination (i.e. type of fruits, acidity and sugar content).

Biocompatible caramelized carbonaceous nanospheres supported paramagnetic ultrathin manganese oxide nanosheets via self-sacrificing reduction as a MRI contrast agent for liver imaging

The elimination of nanoparticles remains the major roadblock to clinical translation. Caramelization reaction is a general type of non-enzymatic browning reactions to food caramels, the products of carbonaceous nanospheres can be considered safe for biological applications. Here, we report a biocompatible caramelized carbonaceous nanospheres supported paramagnetic ultrathin manganese oxide nanosheets via self-sacrificing reduction as a liver MRI contrast agent and for T1-weighted MR imaging, which are taken up by Kupffer cells resulting in a high relaxivity rate. Mn3O4-caramelized nanoparticles (Mn3O4-CNPs) were synthesized and their characteristics as MR contrast agents were investigated. The relaxation rate (r1) of Mn3O4-CNPs is calculated to 11.6 mM−1 s−1 by Mn concentrations and is nearly three times commercial GdIII-based complex agents at a 3.0 T clinical MR scanner, and the in vivo experiment shows that the signals of mouse liver increase by 50.1% under T1-weighted imaging in 4 h post-injection of Mn3O4-CNPs. The in vivo bio-distribution reveals that the concentrations of Mn are equal to the pre-injection after post-injection of Mn3O4-CNPs 48 h. Therefore, the Mn3O4-CNPs can be used as biocompatible liver MR contrast agents.

Optimum condition of producing crisp osmotic banana using superheated steam puffing.

Puffing can improve textural property of snacks. Nevertheless, high temperature puffing accelerates non-enzymatic browning reactions. The osmotic treatment using sucrose solution potentially retards the browning, but the high amount of sucrose gain causes hard texture. The objective of this work was therefore to study the effects of osmotic time, puffing time and puffing temperature on banana qualities such as colour, shrinkage and textural property. The experimental results showed that puffing temperature, puffing time and osmotic time significantly affected colour, shrinkage and textual properties. The optimisation using response surface methodology was used for a trade-off between colour and textural properties. To obtain a good quality product, the puffed osmotic banana should be operated at the osmotic time of 43 min and puffing temperature of 220 °C and puffing time of 2 min. © 2016 Society of Chemical Industry.

Anthraquinones isolated from the browned Chinese chestnut kernels (Castanea mollissima blume)

Anthraquinones (AQS) represent a group of secondary metallic products in plants. AQS are often naturally occurring in plants and microorganisms. In a previous study, we found that AQS were produced by enzymatic browning reaction in Chinese chestnut kernels. To find out whether non-enzymatic browning reaction in the kernels could produce AQS too, AQS were extracted from three groups of chestnut kernels: fresh kernels, non-enzymatic browned kernels, and browned kernels, and the contents of AQS were determined. High performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) methods were used to identify two compounds of AQS, rehein(1) and emodin(2). AQS were barely exists in the fresh kernels, while both browned kernel groups sample contained a high amount of AQS. Thus, we comfirmed that AQS could be produced during both enzymatic and non-enzymatic browning process. Rhein and emodin were the main components of AQS in the browned kernels.

Ultrasonic accelerates asparagine-glucose non-enzymatic browning reaction without acrylamide formation

Ultrasonic accelerated the asparagine-glucose non-enzymatic browning reaction with significant decrease of glucose and asparagine concentrations, and marked increase of intermediate products (UV-absorbance value at 294nm, Abs294), melanoidins (UV-absorbance value at 420nm, Abs420) and in vitro antioxidant activity (DPPH free radical scavenging activity). As the ultrasonic intensity was 17.83W/cm2, the asparagine-glucose solution’s Abs294, Abs420 and antioxidant activity increased from 0 to 1.26, 0.88 and 21.56%, respectively, and the glucose and asparagine concentrations of the asparagine-glucose solution reduced 58.97 and 12.57%, respectively. The high performance liquid chromatography (HPLC)-Diode Array Detector (DAD) analyses showed that no acrylamide was detected after 50-min ultrasonic reaction. This study suggested that ultrasonic at higher intensity was a potential method to accelerate the non-enzymatic browning reaction in the asparagine-glucose solution without acrylamide production.

Non-enzymatic browning reaction of glucosamine at mild conditions: Relationship between colour formation, radical scavenging activity and α-dicarbonyl compounds production

Glucosamine (GlcN, 5% w/v) was incubated in either phosphate buffer or ammonium hydroxide solutions at 40 and 60°C for up to 48h in order to yield caramel solutions. Non-enzymatic browning was monitored via changes in absorption at 280, 320 and 420nm and the physico-chemical properties as well as the generation of short chain α-dicarbonyl compounds were evaluated. Accumulation of GlcN autocondensation products (280nm) proceeded in parallel with the development of pre-melanoidins (320nm) and melanoidins (420nm). The reactive α-dicarbonyls were detected at temperature as low as 40°C within 3h with a maximum level of diacetyl recorded at 6h. The caramel solutions showed a high efficacy in scavenging DPPH and ABTS radicals in accordance with the increasing browning intensity. The results suggest that GlcN browning can be modulated according to the specific desired properties to produce a multi-functional food ingredient that has health-promoting effects.

Effects of Glycated Whey Protein Concentrate on Pro-inflammatory Cytokine Expression and Phagocytic Activity in RAW264.7 Macrophages

The aim of this study was to determine the stimulatory effects of Maillard reaction, a non-enzymatic browning reaction on the expression of pro-inflammatory cytokines and phagocytic activity induced by whey protein concentrate (WPC). Glycated WPC (G-WPC) was prepared by a reaction between WPC and the lactose it contained. The fluorescence intensity of G-WPC dramatically increased after one day, and high molecular weight complexes formed via the Maillard reaction were also observed in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles. G-WPC demonstrated immunomodulatory effects, including stimulation of increased nitric oxide production and cytokine expressions (i.e., tumor necrosis factor-α, interleukin (IL)-1β, and IL-6), compared to WPC. Furthermore, the phagocytic activity of RAW264.7 cells was significantly increased upon treatment with G-WPC, compared to WPC. Therefore, we suggest that G-WPC can be utilized as an improved dietary source for providing immune modulating activity.

Marine phospholipids: The current understanding of their oxidation mechanisms and potential uses for food fortification

ABSTRACTThere is a growing interest in using marine phospholipids (PL) as ingredient for food fortification due to their numerous health benefits. However, the use of marine PL for food fortification is a challenge due to the complex nature of the degradation products that are formed during the handling and storage of marine PL. For example, nonenzymatic browning reactions may occur between lipid oxidation products and primary amine group from phosphatidylethanolamine or amino acid residues that are present in marine PL. Therefore, marine PL contain products from nonenzymatic browning and lipid oxidation reactions, namely, Strecker aldehydes, pyrroles, oxypolymers, and other impurities that may positively or negatively affect the oxidative stability and quality of marine PL. This review was undertaken to provide the industry and academia with an overview of the current understanding of the quality changes taking place in PL during their production and their storage as well as with regards to their utilization for food fortification.

D-Galacturonic Acid: A Highly Reactive Compound in Nonenzymatic Browning. 2. Formation of Amino-Specific Degradation Products.

Thermal treatment of aqueous solutions of D-galacturonic acid and L-alanine at pH 3, 5, and 8 led to rapid and more intensive nonenzymatic browning reactions compared to similar solutions of other uronic acids and to Maillard reactions of reducing sugars. The hemiacetal ring structures of uronic acids had a high impact on browning behavior and reaction pathways. Besides reductic acid (1,2-dihydroxy-2-cyclopenten-1-one), 4,5-dihydroxy-2-cyclopenten-1-one (DHCP), furan-2-carboxaldehyde, and norfuraneol (4-hydroxy-5-methyl-3-(2H)-furanone) could be detected as typical products of nonenzymatic uronic acid browning reactions. 2-(2-Formyl-1H-pyrrole-1-yl)propanoic acid (FPA) and 1-(1-carboxyethyl)-3-hydroxypyridin-1-ium (HPA) were identified as specific reaction products of uronic acids with amine participation like l-alanine. In contrast, the structurally related D-galacturonic acid methyl ester showed less browning activity and degradation under equal reaction conditions. Pectin-specific degradation products such as 5-formyl-2-furanoic acid and 2-furanoic acid were found but could not be verified for d-galacturonic acid monomers alone.