Thermal Degradation Characteristics and Antioxidant Activity of Fructose Solution with Heating Temperature and Time

Deep eutectic solvent-based shaking-assisted extraction for determination of bioactive compounds from Norway spruce roots

Polyphenolic compounds play an essential role in plant growth, reproduction, and defense mechanisms against pathogens and environmental stresses. Extracting these compounds is the initial step in assessing phytochemical changes, where the choice of extraction method significantly influences the extracted analytes. However, due to environmental factors, analyzing numerous samples is necessary for statistically significant results, often leading to the use of harmful organic solvents for extraction. Therefore, in this study, a novel DES-based shaking-assisted extraction procedure for the separation of polyphenolic compounds from plant samples followed by LC-ESI-QTOF-MS analysis was developed. The DES was prepared from choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and fructose (Fru) as the hydrogen bond donor (HBD) at various molar ratios with the addition of 30% water to reduce viscosity. Several experimental variables affecting extraction efficiency were studied and optimized using one-variable-at-a-time (OVAT) and confirmed by response surface design (RS). Nearly the same experimental conditions were obtained using both optimization methods and were set as follows: 30 mg of sample, 300 mg of ChCl:Fru 1:2 DES containing 30% w/w of water, 500 rpm shaking speed, 30 min extraction time, 10°C extraction temperature. The results were compared with those obtained using conventional solvents, such as ethanol, methanol and water, whereby the DES-based shaking-assisted extraction method showed a higher efficiency than the classical procedures. The greenness of the developed method was compared with the greenness of existing procedures for the extraction of polyphenolic substances from solid plant samples using the complementary green analytical procedure index (ComplexGAPI) approach, while the results for the developed method were better or comparable to the existing ones. In addition, the practicability of the developed procedure was evaluated by application of the blue applicability grade index (BAGI) metric. The developed procedure was applied to the determination of spruce root samples with satisfactory results and has the potential for use in the analysis of similar plant samples.

Highly efficient fermentation of 5-keto-D-fructose with Gluconobacter oxydans at different scales

BACKGROUND

The global market for sweeteners is increasing, and the food industry is constantly looking for new low-caloric sweeteners. The natural sweetener 5-keto-D-fructose is one such candidate. 5-Keto-D-fructose has a similar sweet taste quality as fructose. Developing a highly efficient 5-keto-D-fructose production process is key to being competitive with established sweeteners. Hence, the 5-keto-D-fructose production process was optimised regarding titre, yield, and productivity.

RESULTS

For production of 5-keto-D-fructose with G. oxydans 621H ΔhsdR pBBR1-p264-fdhSCL-ST an extended-batch fermentation was conducted. During fructose feeding, a decreasing respiratory activity occurred, despite sufficient carbon supply. Oxygen and second substrate limitation could be excluded as reasons for the decreasing respiration. It was demonstrated that a short period of oxygen limitation has no significant influence on 5-keto-D-fructose production, showing the robustness of this process. Increasing the medium concentration increased initial biomass formation. Applying a fructose feeding solution with a concentration of approx. 1200 g/L, a titre of 545 g/L 5-keto-D-fructose was reached. The yield was with 0.98 g_{5-keto-d-fructose}/g_fructose close to the theoretical maximum. A 1200 g/L fructose solution has a viscosity of 450 mPa∙s at a temperature of 55 °C. Hence, the solution itself and the whole peripheral feeding system need to be heated, to apply such a highly concentrated feeding solution. Thermal treatment of highly concentrated fructose solutions led to the formation of 5-hydroxymethylfurfural, which inhibited the 5-keto-D-fructose production. Therefore, fructose solutions were only heated to about 100 °C for approx. 10 min. An alternative feeding strategy was investigated using solid fructose cubes, reaching the highest productivities above 10 g_{5-keto-d-fructose}/L/h during feeding. Moreover, the scale-up of the 5-keto-D-fructose production to a 150 L pressurised fermenter was successfully demonstrated using liquid fructose solutions (745 g/L).

CONCLUSION

We optimised the 5-keto-D-fructose production process and successfully increased titre, yield and productivity. By using solid fructose, we presented a second feeding strategy, which can be of great interest for further scale-up experiments. A first scale-up of this process was performed, showing the possibility for an industrial production of 5-keto-D-fructose.

Validation of a Rapid Ultrasound-Assisted Extraction Coupled with Anion Exchange Chromatography Method for the Determination of D-Psicose in Raisin Matrices

D-psicose is a rare sugar, used as an alternative to the natural sweetener that provides 70% of sucrose’s sweetness, with low-calorie absorption in the human body. Considering the health-beneficial effect and high availability of D-psicose in raisins (the world’s most consumed dried fruit), it is of interest to establish a reliable analytical method to determine D-psicose content in these matrices. Herein, a new method for determining D-psicose content in raisins, using ultrasound-assisted extraction in conjunction with anion exchange chromatography with pulsed amperometric detection (UAE-HPAEC-PAD) systems, has been developed and validated. The stability of D-psicose and its precursor was priorly assessed by applying a specific ultrasound power (100 W) and pulse duty cycle (0.5 s−1), with varying extraction temperatures (10, 25, 40, 55, 70, and 85 °C) and times (5, 10, 15, 20, and 25 min). The method was validated with high linearity (R2 > 0.999), accuracy (89.78–101.06%), and precision (4.8% intra-day and 4.34% inter-day). A number of raisin products were checked during the method applicability assessment. A concentration of 520 mg kg−1 was found in a specimen of commercial raisin matrix.

Effects of Sodium Alginate, Pectin and Chitosan Addition on the Physicochemical Properties, Acrylamide Formation and Hydroxymethylfurfural Generation of Air Fried Biscuits

This study evaluated the effects of sodium alginate, pectin and chitosan addition (0.5–1.5%) on the physicochemical properties including pH, water activity, moisture content, color values, hardness, diameter, thickness, spread ratio, antioxidant activities and sensory scores of biscuits in air frying processing. In addition, the formation of acrylamide and hydroxymethylfurfural (HMF) were discussed. Physicochemical properties of biscuits including water content, water activity, hardness, appearance, shape, color, flavor, texture, overall acceptability, and DPPH radical scavenging activity of biscuits were not influenced significantly by the addition (0.5–1.0%) of three food hydrocolloids. The data showed that the biscuits with hydrocolloids addition had lower acrylamide contents than that of the control biscuit without hydrocolloids addition, and the reducing power of biscuits increased after adding the hydrocolloids. The highest mitigation of acrylamide formation was obtained by the chitosan addition formulation. The formation of acrylamide showed a negative correlation with the content of sodium alginate and chitosan addition, and they were effective ingredients in terms of mitigating the formation of acrylamide in biscuit formulation.

A Novel Method for Quality Evaluation of Gardeniae fructus Praeparatus during Heat Processing Based on Sensory Characteristics and Chemical Compositions

The intrinsic chemical components and sensory characteristics of Gardeniae fructus Praeparatus (GFP) directly reflect its quality and subsequently, affect its clinical curative effect. However, there is little research on the correlation between the appearance traits and chemical compositions of GFP during heat processing. In this study, the major components of five typical processed decoction pieces of GFP were determined. With the deepening of processing, the contents of geniposidic acid and 5-HMF gradually increased, while the contents of deacetyl-asperulosidic acid methyl ester, gardenoside, and two pigments declined. Moreover, the electronic eye, electronic tongue, and electronic nose were applied to quantify GFP’s sensory properties. It was found that the chroma values showed a downward trend during the processing of GFP. The results of odor showed that ammonia, alkenes, hydrogen, and aromatic compounds were the material base for aroma characteristics. Complex bitterness in GF was more obvious than that in other GFP processed products. Furthermore, one mathematical model was established to evaluate the correlation between the sensory characteristics and chemical composition of GFP during five different stages. A cluster analysis and neural network analysis contributed to recognizing the processing stage of GFP. This study provided an alternative method for the exterior and interior correlation-based quality evaluation of herbs.

Comparative Analysis of Commercial Chinese Bean Sauce (Chunjang) from Korea and China Based on Antioxidant Activity

In this study, the antioxidant effects of seven types of commercial Chunjang from China (C1∼3) and Korea (K1∼4) were compared for their ability to protect against H₂O₂-induced DNA damage. Outputs included total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH RSA), oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant potential (TRAP), and comet assays. TPC was the highest in C3 (1,250.8 mg gallic acid equivalent/100 g). C1 exhibited a significantly higher DPPH RSA IC₅₀ (7.5 mg/mL) and ORAC concentration (8.22 μM Trolox equivalent) compared with all other samples, and C1 and K1 exhibited the highest TRAPs. H₂O₂-induced DNA damage was effectively protected by Chunjang, with a higher observed in C2, C3, and K1 (24.2∼25.3 μg/mL) compared with the other samples (28.3∼30.0 μg/mL). Our results showed that commercial Chunjang contains polyphenol and antioxidant activities. The differences between the samples might be attributed to different origins, materials, and processing methods.

Changes in the functional components and radical scavenging activity of maize under various roasting conditions

The phenolic compounds and radical scavenging activity of ethanolic extracts from maize at various roasting conditions were evaluated in this research. The free sugar contents in roasted maize significantly decreased with higher roasting temperature and longer roasting time. The total polyphenol and total flavonoid contents in roasted maize significantly increased with higher roasting temperature and longer roasting time. The predominant phenolic acid in the roasted maize was homogentisic acid. The contents of homogentisic acid and myricetin in roasted maize significantly increased with higher roasting temperature and longer roasting time. The DPPH and ABTS radical scavenging activities of roasted maize significantly increased with higher roasting temperature and longer roasting time. DPPH and ABTS radical scavenging activities were positively correlated with phenolic compounds. The activities of these components increased following heat treatments because of the low molecularization effects of the heating process, which resulted in active, low-molecular-weight components that were readily extracted.

Influence of organic acids and heat treatment on ginsenoside conversion

Background

Heat treatments are applied to ginseng products in order to improve physiological activities through the conversion of ginsenosides, which are key bioactive components. During heat treatment, organic acids can affect ginsenoside conversion. Therefore, the influence of organic acids during heat treatment should be considered.

Methods

Raw ginseng, crude saponin, and ginsenoside Rb₁ standard with different organic acids were treated at 130°C, and the chemical components, including ginsenosides and organic acids, were analyzed.

Results

The organic acid content in raw ginseng was 5.55%. Organic acids were not detected in crude saponin that was not subjected to heat treatment, whereas organic acids were found in crude saponin subjected to heat treatment. Major ginsenosides (Rb₁, Re, and Rg₁) in ginseng and crude saponin were converted to minor ginsenosides at 130°C; the ginsenoside Rb₁ standard was very stable in the absence of organic acids and was converted into minor ginsenosides in the presence of organic acids at high temperatures.

Conclusion

The major factor affecting ginsenoside conversion was organic acids in ginseng. Therefore, the organic acid content as well as ginsenoside content and processing conditions should be considered important factors affecting the quality of ginseng products.

The colorants, antioxidants, and toxicants from nonenzymatic browning reactions and the impacts of dietary polyphenols on their thermal formation

Nonenzymatic browning reactions proceed with the starting reactants of sugar and/or protein during thermal processing and storage of food.

Changes in ginsenoside compositions and antioxidant activities of hydroponic-cultured ginseng roots and leaves with heating temperature

Background

This study evaluated changes in ginsenoside compositions and antioxidant activities in hydroponic-cultured ginseng roots (HGR) and leaves (HGL) with heating temperature.

Methods

Heat treatment was performed at temperatures of 90°C, 110°C, 130°C, and 150°C for 2 hours.

Results

The ginsenoside content varied significantly with heating temperature. The levels of ginsenosides Rg1 and Re in HGR decreased with increasing heating temperature. Ginsenosides F2, F4, Rk3, Rh4, Rg3 (S form), Rg3 (R form), Rk1, and Rg5, which were absent in the raw ginseng, were formed after heat treatment. The levels of ginsenosides Rg1, Re, Rf, and Rb1 in HGL decreased with increasing heating temperature. Conversely, ginsenosides Rk3, Rh4, Rg3 (R form), Rk1, and Rg5 increased with increasing heating temperature. In addition, ginsenoside contents of heated HGL were slightly higher than those of HGR. The highest extraction yield was 14.39% at 130°C, whereas the lowest value was 10.30% at 150°C. After heating, polyphenol contents of HGR and HGL increased from 0.43 mg gallic acid equivalent/g (mg GAE eq/g) and 0.74 mg GAE eq/g to 6.16 mg GAE eq/g and 2.86 mg GAE eq/g, respectively.

Conclusion

Antioxidant activities of HGR and HGL, measured by 1,1-diphenyl-2-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging ability, increased with increasing heating temperature. These results may aid in improving the biological activity and quality of ginseng subjected to heat treatments.