Non-enzymatic Browning Index Research Articles

Effects of roasting temperature and duration on fatty acid composition, phenolic composition, Maillard reaction degree and antioxidant attribute of almond (Prunus dulcis) kernel

Roasting treatment increased levels of unsaturated fatty acids (linoleic, oleic and elaidic acids) as well as saturated fatty acids (palmitic and stearic acids) in almond (Prunus dulcis) kernel oils with temperature (150 or 180°C) and duration (5, 10 or 20min). Nonetheless, higher temperature (200°C) and longer duration (10 or 20min) roasting might result in breakdown of fatty acids especially for unsaturated fatty acids. Phenolic components (total phenols, flavonoids, condensed tannins and phenolic acids) of almond kernels substantially lost in the initial phase; afterward these components gradually increased with roasting temperature and duration. Similar results also observed for their antioxidant activities (scavenging DPPH and ABTS+ radicals and ferric reducing power). The changes of phenolic acid and flavonoid compositions were also determined by HPLC. Maillard reaction products (estimated with non-enzymatic browning index) also increased with roasting temperature and duration; they might also contribute to enhancing the antioxidant attributes.

Process integration for purification and concentration of red cabbage (Brassica oleracea L.) anthocyanins

Multistage aqueous two phase extraction was carried out using polyethylene glycol (PEG) 4000/magnesium sulfate (14.8/10.3%, w/w) system. The phase forming polymer (PEG 4000) was successfully separated from anthocyanins employing organic–aqueous extraction. Different processes employed for the purification and concentration of anthocyanins were compared with one another. The highest concentration of anthocyanins (3123.45mg/L and 43°Brix) was obtained in case of integration of aqueous two phase extraction with forward osmosis. Non-enzymatic browning index (0.11) and degradation constant (0.21) were found to be lowest in case of the integrated process involving aqueous two phase extraction followed by forward osmosis when compared to other processes. Color density was found to increase from 0.6 to 14.56 and stability of anthocyanins (with respect to pH and temperature) was found to be more in case of integrated process (aqueous two phase extraction followed by forward osmosis).

Purification of anthocyanins from jamun (Syzygium cumini L.) employing adsorption

The present study deals with the downstream processing of anthocyanins from jamun (Syzygium cumini L.) in order to obtain anthocyanins in a purified form. Adsorption was carried out employing six different adsorbents and among these, Amberlite XAD7HP showed the highest adsorption capacity (1.07mg/mL of adsorbent) and desorption ratio (87.62%). Aqueous acidified ethanol (above 40%, v/v) could effectively elute the anthocyanins. Adsorption results were found to correlate best using the Langmuir equation at all the temperatures studied. Second order kinetics model was found to be more appropriate to describe the adsorption of anthocyanins. The dynamic adsorption process parameters for the purification of anthocyanins using Amberlite XAD7HP arrived at were as follows; for adsorption: processing volume, flow rate and temperature were 6.5BV, 1mL/min and 25±1°C, respectively and for desorption: eluent volume and flow rate were 4 BV of acidified aqueous ethanol (40%, v/v) and 1mL/min, respectively. Anthocyanins extract after purification was found to be free of sugars, which are the major cause for degradation of anthocyanins. After the purification by adsorption, the degradation constant and non-enzymatic browning index of anthocyanins were found to decrease from 0.93 to 0.19 and 0.45 to 0.29, respectively. The qualitative determination of anthocyanins after adsorption was evaluated by the physio-chemical characteristics and the structural stability was confirmed by HPLC–MS/MS.

Optimization of spray drying process in cheese powder production

In this study, white cheese powder was produced using a pilot scale spray drier and response surface methodology was used to optimize the operating conditions of spray drying. The independent variables were inlet drying temperature, atomization pressure and outlet drying temperature, while drying experiments were carried out with an inlet drying air temperature range of 160–230°C, an outlet drying air temperature range of 60–100°C and an atomization pressure range of 294–588kPa. The responses were nonenzymatic browning index, free fat content, solubility index, bulk density of cheese powder and exergy efficiency of the spray drying process. Optimum operating conditions were found to be an inlet drying temperature of 174°C, atomization pressure of 354kPa, and an outlet drying temperature of 68°C. At this optimum condition, nonenzymatic browning index, free fat content, solubility index, bulk density and exergy efficiency were found to be 0.123OD/gdm, 40.7%, 82.7%, 252kg/m3 and 4.81%, respectively.

Catalytic Infrared Drying Effect on Tomato Slices Properties

In this study, the effect of distance between Far-Infrared Radiation (FIR) emitter and the surface of tomato slices and sample thickness on drying time, non-enzymatic browning, brightness, the ratio of redness to yellowness, ascorbic acid content, and lycopene content of the dried tomato slices was investigated. Three levels of distance (38 to 50 cm), sample thickness (7 to 11 mm) were used for the experiment. The desirability index technique was used to determine the ideal drying conditions that yield minimum drying time and non-enzymatic browning and maximum brightness color, redness to yellowness ratio, lycopene content, and ascorbic acid of drying of tomato slices. At the best conditions of 40.29 cm distance and 9.04 mm sample thickness, the drying time was 108 ± 4 minutes; the non-enzymatic browning index was 0.338 ± 0.12 Abs unit; the brightness was 40.43 ± 2.29; the ratio of redness to yellowness was 0.92 ± 0.13; the ascorbic acid content was 3.76 ± 0.27 mg/g dry matter; and the lycopene content was 72.34 ± 19.87 mg/100 g dry matter. These results demonstrate that FIR should be considered as an efficient drying method for tomato with respect to colour and ascorbic acid preservation, minimization of brown pigment formation and increment in lycopene content.

Process Optimization for Foam Mat-Tray Drying of Passiflora edulis Flavicarpa Pulp and Characterization of the Dried Powder

Abstract Passion fruit (Passiflora edulis flavicarpa) is a seasonal, tropical, pulpy fruit, known for a rich source of Vitamin C, antioxidants, and delicate flavor. Presently, freezing technique has been used to preserve the pulp. This article reports alternate method of preservation by foam mat convective air drying of fruit pulp under moderate temperatures. The optimization of process parameters, particularly air temperature, was done with subsequent mathematical modeling of the process and assessment of quality parameters by retention of physicochemical properties and antioxidant capacity of the fruit powder. Sixty degree Celsius was found to be the optimum temperature, and Henderson and Pabis model showed best fit to the drying characteristics data (R2 = 0.99). Diffusivity characteristics of moisture during drying were also studied. As drying temperature was increased, total color difference and rehydration ratio decreased, whereas non-enzymatic browning index, total phenolic content, and total antioxidant activity showed increase that was attributed to inhibition of oxidative enzymes and biochemical changes. Dried passion fruit powder showed overall acceptability in terms of organoleptic properties and total antioxidant activity.

Impact of Nonthermal Pulsed Electric Field on Bioactive Compounds and Browning Activity in Emblica officinalis Juice

The effect of nonthermal pulsed electric field (PEF) and thermal treatment (90⁰C for 60s) was studied on quality parameters of Emblica officinalis juice for the period of 6 weeks at 4⁰C using monopolar rectangular pulse of 1µs width. The PEF treatment was given using static chamber at 24kV/cm for 500µs. The quality of Emblica officinalis juice was investigated in terms of non enzymatic browning index (NEBI), 5-hydroxymethyl-2-furfural (HMF), total polyphenol content and antioxidant capacity. ⁰Brix, pH and conductivity were evaluated as physical parameters. The aim of the work was to investigate the effect of PEF on the retention of bioactive compounds and retardation of browning activity. The results showed that conventional thermal treatment had led to a significant (p<0.05) decrease of 48.15% in polyphenol content (129.56 mg of GAE L-1), with higher NEBI and HMF formation (p < 0.05) whilst PEF suppressed NEBI and retained higher polyphenol compounds (168.59mg GAE L-1) with limiting the loss to 32.56% along maximum free radical scavenging activity (92.07%). However, pH, ⁰brix and electrical conductivity of treated juice samples remain unaffected. Therefore, PEF can be considered as an effective nonthermal treatment for retaining bioactive compounds along suppressing browning of emblica juice.

Cookie making behavior of wheat–barley flour blends and effects on antioxidant properties

Refined wheat flour was replaced with whole barley flour at varying levels and the blends were evaluated for their cookie making behavior. The spread factor of cookies decreased as the proportion of barley flour increased while snap force and water activity increased significantly upto 114.7 N and 0.397 in only barley flour cookies. Increasing levels of barley flour lead to a significant decrease in L∗ and b∗ values of cookie dough. Peak viscosity (PV) and final viscosity (FV) increased significantly as the levels of barley flour increased. A significant increase in antioxidant activity (AOA), total phenolic content (TPC), metal chelating activity (MCA), reducing power (RP) and total flavonoid content (TFC) was observed as the proportion of barley flour increased. Baking lead to a significant decrease in TPC and TFC whereas AOA, MCA and RP increased. Baking lead to a significant increase in the non-enzymatic browning index of cookies.

Changes in Extractive Components during Spontaneous Fermentation of Fish Sauce Using Eel Intestines

To reuse the waste of fishery resources in a preliminary study, we have described changes in extractive components during spontaneous fermentation of fish sauce using eel intestines. This study was aimed at investigating the chemical analysis of extractive components from fermented eel intestines with a view to using it as a food condiment. Fish sauce was produced via fermentation of by-products (intestinal) of processed eel with 35% (w/w) of salt for 180 days. During 180 days of fermentation, the pH decreased to approximately 4.8, and the overall trend of total nitrogen, amino acid nitrogen, non-enzymatic browning index and total volatile basic nitrogen were increasing. The changes and the trend mentioned above indicated that it was a practical method to produce fish sauce using eel intestines, but the spontaneous fermentation cycle was long (more than 6 months).

Variation in ultrasonic frequency and time as pre-treatments to air-drying of carrot

Vegetable drying is an alternative method to curb post harvest decay of vegetables and a process to produce dried vegetables, which can be directly consumed or used as ingredients for the preparation of soups, stews, baby foods, cakes, puddings, and many other foods. In this study, the effect of ultrasound frequency and sonication time as pre-treatment prior to air drying at 70°C at an air velocity of 0.5 m/s, on carrot drying kinetics, flavour, colour, and non-enzymatic browning was investigated using a 3-level factorial response surface method. The result showed that an increase in sonication frequency and time did not significantly increase moisture diffusivity but in comparison with the control, water diffusivity increased after ultrasound application and the overall drying time was reduced. Application of the ultrasound pre-treatment in distilled water resulted in water gain and sugar loss, indicating that the ultrasonic pre-treatment can be an important step to produce low sugar content dried products. The brightness and redness to yellowness values of the ultrasonically pre-treated dried carrots were better than those without ultrasound application. In comparison with the flavour of the control, the ultrasound pre-treated samples recorded higher flavour response signals, indicating that the application of ultrasound improved the flavour of the dried carrot. The variation in sonication frequency and time did not significantly affect the non-enzymatic browning index of the dried products but were better than the control.

Variation in ultrasonic frequency and time as pre-treatments to air-drying of carrot

Vegetable drying is an alternative method to curb post harvest decay of vegetables and a process to produce dried vegetables, which can be directly consumed or used as ingredients for the preparation of soups, stews, baby foods, cakes, puddings, and many other foods. In this study, the effect of ultrasound frequency and sonication time as pre-treatment prior to air drying at 70°C at an air velocity of 0.5 m/s, on carrot drying kinetics, flavour, colour, and non-enzymatic browning was investigated using a 3-level factorial response surface method. The result showed that an increase in sonication frequency and time did not significantly increase moisture diffusivity but in comparison with the control, water diffusivity increased after ultrasound application and the overall drying time was reduced. Application of the ultrasound pre-treatment in distilled water resulted in water gain and sugar loss, indicating that the ultrasonic pre-treatment can be an important step to produce low sugar content dried products. The brightness and redness to yellowness values of the ultrasonically pre-treated dried carrots were better than those without ultrasound application. In comparison with the flavour of the control, the ultrasound pre-treated samples recorded higher flavour response signals, indicating that the application of ultrasound improved the flavour of the dried carrot. The variation in sonication frequency and time did not significantly affect the non-enzymatic browning index of the dried products but were better than the control.

Optimization of Drying Conditions for Quality Dried Tomato Slices Using Response Surface Methodology

The response surface method was used to investigate the results of experiment designed with the Box-Behken approach to make known the effects of air temperature, air velocity and sample thickness, on drying time, lycopene content, ascorbic acid content, non-enzymatic browning and color of dried tomato slices. Three levels of temperature (40 to 60C), air velocity (1.0 to 2.0 m/s) and sample thickness (7 to 11 mm) were used for the experiment. The desirability index technique was used to predict the ideal drying condition. At the best conditions of 44C air temperature, 2.0 m/s air velocity and 7.72 mm sample thickness, drying time was 527 ± 76 min, lycopene content was 62.7 ± 4.3 mg/100 g dry matter, ascorbic acid content was 3.07 ± 0.14 mg/g dry matter, brightness value was 62.92 ± 2.18, ratio of redness to yellowness was, 0.78 ± 0.05 and the non-enzymatic browning index was 0.55 ± 0.06 absorbance unit. Practical Applications The research took practical desires of minimum drying time and non-enzymatic browning and maximum values of lycopene content, ascorbic acid, color brightness and redness to yellowness ratio into consideration. These quality indicators are of topmost importance to the food industries involved in tomato drying. The quality of dried products obtained using response surface methodology provides industries with optimized conditions for improving the quality of dried tomatoes. The dried product is a valuable ingredient in the preparation ready to enjoy soups, sauces and pizzas.

Effect of incorporating hydrothermal, kilned and defatted oats on antioxidant and chapatti making properties of wheat flour

Oats were subjected to treatments like defatting, hydrothermal cooking and kilning, milled into flour and then the control and treated flours were incorporated into wheat flour at 25% and 50% levels and chapatti making behaviour and antioxidant properties were studied. The treatments significantly affected the antioxidant properties of oats. Incorporating oat flours to wheat increased total phenolic content but lowered the antioxidant activity however both were decreased significantly upon baking. The reducing power of the oat blended flour was higher than the wheat flours and ranged from 8.0 to 15.5μmol AAE/g and was further increased upon baking. The metal chelating activity of flour blends varied from 62.0% to 73.8% and further increased upon baking. After baking the total flavonoid content was lowered and ranged from 308 to 389μg CE/g. The non-enzymatic browning index significantly increased up to 27.6% upon baking.

Apricot Nectar Processing by Pulsed Electric Fields

Application of pulsed electric fields to process apricot nectar by determining the pH, °Brix, total acidity, conductivity, color, non-enzymatic browning index, concentration of mineral ions, and retention of ascorbic acid and beta carotene as well as inactivation of Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Pseudomonas syringae subs. syringae, Erwinia carotowora, Penicillum expansum, and Botrytis cinerea was explored in this study. Processing of apricot nectar did not cause a significant difference in measured attributes (p > 0.05). However, inactivation of all microorganisms was significantly increased with increased electric field strength and treatment time (p ≤ 0.05). Microbial inactivation data fit both the Weibull distribution and log-logistic model.

INFLUENCE OF COMBINED MICROWAVE‐VACUUM DRYING ON DRYING KINETICS AND QUALITY OF DRIED TOMATO SLICES

ABSTRACTThe study investigated the influence of four microwave powers on the drying kinetics and quality of tomato slices in a microwave‐vacuum dryer at vacuum pressures of 0.04, 0.05 and 0.06 MPa. The results showed that increase in microwave‐vacuum drying conditions increased drying rates and resulted in decreased drying time from 84 to 14 min. The nonenzymatic browning index increased with microwave power whereas the overall flavor degradation was between 18.99 and 20.80%. The brightness and the yellowness of the dried tomatoes generally increased but there was a slight reduction in redness when compared with the fresh. The effective moisture diffusivity increased with microwave power and was 7.22 × 10−9, 9.10 × 10−9, 14.99 × 10−9 and 25.19 × 10−9 m2/s at respective microwave powers of 200, 300, 500 and 700 W.PRACTICAL APPLICATIONSMicrowave‐vacuum drying is one of the advanced methods with numerous advantages including high thermal efficiency, shorter drying time and improved product quality. Tomato is the second most important vegetable with enormous health benefits, which include reduction of cholesterol, improvement of vision, maintenance of gut, lowering of hypertension, alleviation of diabetes, and prevention of urinary tract infections and gallstones. The quality of dried products obtained using the microwave‐vacuum dryer provides industries with method that can be used to enhance the quality of dried tomatoes. The dried product is a valuable ingredient in the preparation of soups and sauces, as well as in cosmetics and pharmaceutical formulations.

Effect of water activity on anthocyanin degradation and browning kinetics at high temperatures (100–140 °C)

The effect of water activity on anthocyanin degradation and non-enzymatic browning (NEB) indices was determined in a blackberry juice system heated to high temperature. Blackberry juice samples mixed with quartz sand at three different water activities (aw of 0.34, 0.76 and 0.95) and having the same concentration of anthocyanins (51±4mg100g−1 WB) were heated in a hermetically sealed reactor under non-isothermal conditions (100 to 140°C). Reaction kinetics were well-represented by first-order reaction models. A non-isothermal method was used for the identification of kinetic parameters, and the confidence interval for each parameter was determined via Monte-Carlo simulations. The estimated parameters revealed an increase in the anthocyanin degradation reaction rate constant (kref) from 0.9 to 3.5×10−3s−1 as the water activity decreased from 0.99 to 0.34. The corresponding activation energies (Ea) for anthocyanins and NEB index were modified to a lesser extent by variations in water activity. Hence, the reduction of water activity had a negative effect on anthocyanin stability at high temperatures.

Antioxidant activity of barley as affected by extrusion cooking

Grit from different hulled barley cultivars was subjected to extrusion cooking and the effect of extrusion moisture and temperature on the antioxidant properties was studied. A significant decrease in the total phenolic content (TPC) and total flavonoid content (TFC) was observed upon extrusion and a further decrease of 8–29% in TPC and 13–27% in TFC was observed when both the feed moisture and extrusion temperature were increased. The antioxidant activity (AOA) increased significantly upon extrusion and this increase was the highest (36–69%) at 150°C and 20% feed moisture. The increase in feed moisture and temperature significantly increased the metal chelating activity. The reducing power decreased significantly upon extrusion as compared to their corresponding control samples. Extrusion lead to a greater increase in non-enzymatic browning (NEB) index however, increasing the moisture content of feed decreased the NEB index by 3–29% (at 180°C) and 1–17% (150°C), while increasing the temperature increased the NEB significantly.

PROCESSING OF PEACH NECTAR BY PULSED ELECTRIC FIELDS WITH RESPECT TO PHYSICAL AND CHEMICAL PROPERTIES AND MICROBIAL INACTIVATION

ABSTRACTApplicability of pulsed electric fields (PEFs) to process peach nectar as a function of electric field strength and treatment time with respect to microbial inactivation and measurement of physical and chemical properties of peach nectar was evaluated. No significant difference was detected in terms of pH, °Brix, titration acidity (TA), conductivity, color (L*, a* and b*), nonenzymatic browning index (NBI), metal ion concentration, ascorbic acid content and beta carotene concentration between control and PEF‐treated peach nectar samples (P &gt; 0.05). On the other hand, Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes, Erwinia carotowora, Pseudomonas syringae, Botrytis cinerea and Penicillum expansum were significantly inactivated (P ≤ 0.05). PEF can successfully be applied to peach nectar with significant amount of microbial inactivation without a significant adverse effect on physical and chemical properties.PRACTICAL APPLICATIONSPulsed electric field (PEF) processing, considered a novel technology, posses a significant potential to achieve nonthermal (cold) pasteurization and/or sterilization of liquid materials, especially fruit juices. This study was performed to determine potential use of PEF to process peach nectar based on the measurement of changes in physical and chemical properties as well as in microbial inactivation. PEF processing significantly inactivated inoculated microorganisms without adverse effects on both physical and chemical properties. Based on the results, it can be concluded that PEF technology can successfully be applied pasteurization of peach nectar.

Effect of sand roasting on beta glucan extractability, physicochemical and antioxidant properties of oats

The antioxidant properties, damaged starch, beta glucan extractability and physicochemical properties of ten different oat cultivars were studied after sand roasting at 280 °C for 15 s. The groat content within the cultivars varied from 6.59 to 7.76 g/10 g oats. Roasting lowered the length/breadth ratio and bulk density and resulted in puffing of the groats. Color characteristics a∗ indicating redness and b∗ indicating yellowness and nonenzymatic browning index significantly (p < 0.05) increased upon roasting. The total phenolic (μg FAE/g) and flavonoid content (μg/g) decreased significantly by 11.4–50.2% and 22.7–49.9%, respectively. An increase in reducing power (μmol AAE/g) ranging from 1.1 to 37.6% and metal chelating activity ranging from 13.2 to 180.2% was observed in the roasted groats. The DPPH radical scavenging activity in the roasted groats increased by 4.6–73.0%. The peak viscosity of the roasted groat flour decreased by 9.1–51.1% while the final viscosity decreased by 15.4–57.5%. The damaged starch content in the groats increased after roasting and the increase ranged from 72 to 82%. Roasting significantly increased the extractable beta glucan content in the groats by 9.8–61.1%. It was concluded that roasting significantly affects the physicochemical and pasting behavior of groats and increases the availability of phytochemicals like beta glucan and the total antioxidant activity.

Effect of sand roasting and microwave cooking on antioxidant activity of barley

Eight different barley cultivars were roasted in sand and cooked in a microwave oven and evaluated for antioxidant activity (AOA), total phenolic content (TPC), non-enzymatic browning, polyphenol oxidase activity (PPO), total flavonoid content (TFC), reducing power and metal chelating activity. Sand roasting resulted in higher puffing index. Greater increase in yellowness of the roasted flour was brought about by microwave cooking. A significant decrease in TPC (8.5 to 49.6%) and TFC (24.5 to 53.2%) was observed after roasting. The AOA significantly increased (16.8 to 108.2%) after roasting with sand roasted barley exhibiting higher AOA. The reducing power and metal chelating activity significantly increased by up to 77.5% and 78.9%, respectively after roasting with sand roasted samples showing greater effect. The non-enzymatic browning index increased (315 to 774%) and was higher for sand roasted barley. The microwave cooking brought about a greater reduction (45.1 to 76.8%) in PPO activity.