Loss Of Total Phenolics Research Articles

A Sustainable Approach for Enhancing Stability and Bioactivity of Allium ursinum Extract for Food Additive Applications

Utilizing natural plant extracts as food additives represents a promising strategy for enhancing the quality, nutritional value, and safety of food products, benefiting both consumers and the environment. Therefore, the primary objective of this study was to develop an environmentally sustainable process for the production of solid powder derived from Allium ursinum liquid extract, with the intent of utilizing it as a natural food additive. To address the challenge of instability and enhance the solubility of bioactive compounds in A. ursinum extracts obtained through subcritical water extraction, this study employed the spray drying process. Notably, the results demonstrated the remarkable efficiency of the spray drying process, with maltodextrin as a carrier, yielding uniformly encapsulated particles with an average size of approximately 4 µm, spherical shape with smooth, intact surfaces. The most optimal conditions for achieving the highest content of total phenolics (23.10 mg GAE/g) and total flavonoids (4.92 mg CE/g) in the A. ursinum extract were identified, involving an inlet temperature of 120 °C and an 80% maltodextrin concentration. The encapsulated powders showed excellent stability, with minimal loss of total phenolics (12.64%) and total flavonoids (10.52%) after three months of storage. Physicochemical analysis confirmed the successful preservation of bioactive compounds through microencapsulation using maltodextrin, suggesting its potential for application in innovative food or pharmaceutical products.

Ethanol pretreatment and infrared drying of melon: Kinetics, quality parameters, and NIR spectra

AbstractThere is a growing interest in drying methods focusing on the reduction of drying time, and improvement of product quality. This work aimed to study the use of ethanol as a pretreatment to melon infrared drying (IRD), evaluating its effect on the drying kinetics and quality parameters. The pretreatment step included the melon immersion in different ethanol concentrations (50% and 100%) and immersion times (10, 20, and 30 min). IRD was performed at 60°C with control (untreated) and pretreated samples. Melon pretreated in 100% ethanol for 30 min had the shortest drying time and highest diffusivity value. The Page model obtained the best fit for the experimental data. All dried melons showed water activity below .60, and a reduction in the bioactive compounds. Samples immersed in 50% ethanol, in general, showed lower losses of total phenolics and carotenoids. Concerning color, there was a decrease in the luminosity (L*), while redness (a*) and yellowness (b*) were intensified. Principal component analysis applied to the near infrared (NIR) spectra of the dried samples showed a tendency of separation between samples pretreated with different concentrations of ethanol. In conclusion, IRD and ethanol pretreatment can be useful tools to reduce drying time, but some limitations on bioactive compounds were discussed.Practical applicationsThe concentration and the time of ethanol pretreatment application can result in different melon infrared drying rates and can influence important qualitative parameters. Therefore, it is important to evaluate these factors to optimize the dried melon production, resulting in lower drying time and better quality preservation.

Influence of ultrasound and ethanol as a pretreatment on papaya infrared and convective drying characteristics and quality parameters

AbstractThis study aimed to evaluate the effectiveness of pretreatments on papaya drying behavior and quality parameters. The pretreatment consisted of submerging the samples in ethanol or distilled water for 20 min. The ultrasonic step was conducted in an ultrasonic bath (25 kHz). Samples were dried in an infrared dryer and a convective oven at 60°C. The material pretreated with ultrasound and ethanol and submitted to infrared drying presented the shortest drying time (84 min). The two‐term exponential model was the most predictive for the drying data fitting. All dried samples showed water activity values below 0.60. Among the pretreatments performed, the use of ultrasound associated with ethanol was more effective in reducing losses of total phenolics, ascorbic acid, and antioxidant activity of dried papaya when compared to the use of water. Infrared drying of the fruit pretreated with the combination of ultrasound and ethanol resulted in no significant difference from the untreated papaya concerning the evaluated quality parameters.Practical applicationsThe consumption of tropical fruits and their derived products has increased in national and international markets, due to the growing recognition of their nutritional properties and subsequent use in the food industry. The presence of nutrients such as bioactive compounds, demonstrates their potential for use in different sectors, increasing the added value of the cultivar. Thus, this study represents a contribution to society, recognizing and valuing the consumption of fruit, contributing to the nutritional conditions of the population, favoring food and nutritional security, and conservation of the species. It also allows, with the use of pretreatments and different types of drying, advances, and information about food preservation methods that have a low environmental impact and the exploration of new forms of fruit consumption, increasing its shelf life and facilitating their transport and marketing.

Possible Utilization of Two-Phase Olive Pomace (TPOP) to Formulate Potential Functional Beverages: A Preliminary Study

The demand for functional beverages is expanding over the world. In this work, a rapid, easy and low-cost procedure was followed to prepare a functional beverage (FB) by directly using two-phase olive pomace (TPOP). Liquid ingredients (water and 6% citric acid), extraction systems (heat and ultrasonic treatment), treatment time (30, 60, 90 min) and drying techniques (freeze and air-dried) were studied. Experimented TPOP had a total phenol content of 7.5 mg/g CAE (caffeic acid equivalent), composed majorly of o-diphenols. Air drying of TPOP caused a 50% depletion of total phenols compared to freeze drying. Conversely, no substantial differences were found in the FB, neither for liquid ingredients nor treatment/time adopted. Both 6% citric acid and water were revealed to be profitable liquid ingredients. A 30-min heating treatment was enough to produce a satisfactory beverage, whereas ultrasound treatment caused a loss of total phenols, especially in the water FB. All FBs appeared just limpid after a simple filtration; the citric acid beverage showed reddish color, while water ones were brownish. Finally, the prepared FBs had an average total phenol of about 600 mg/L CAE (by using 300 g/L fresh pomace), with hydroxytyrosol and related compounds being well represented, which confirmed their potential functionality.

Complexation With Polysaccharides Enhanced Polyphenol Gastrointestinal Stability and Activity

Abstract Objectives Fruits and vegetables contain dietary polyphenols and polysaccharides. Accumulating evidence suggests that polyphenol-containing whole foods are protective against inflammation-promoted chronic colonic diseases. However, isolated polyphenols are less stable and may not confer the same gastrointestinal health benefits as that of the whole food matrix. Therefore, we hypothesized that the complexation of anthocyanins, a class of polypheonols, with polysaccharides would enhance colonic concentration and stability of anthocyanins, and attenuate impaired barrier function. Methods In this study, we first extracted the polyphenols from purple-fleshed potatoes and purified them using C18 cartridges into phenolic acid and anthocyanin fractions and confirmed the purity using UPLC. The fractions were complexed with four different polysaccharides (pectin, inulin, starch, cellulose) and their mixture in equal proportions. SEM images were used to visualize the complexation patterns. The stimulated in vitro oral, gastric and small intestine digestion was used to determine the complexation efficiency and stability of anthocyanins. Intestinal permeability was determined using Caco-2/HT29-MTX co-cultures and FITC-dextran. Results Anthocyanins showed significant differences in their complexation pattern with different polysaccharides. After the stimulated in vitro digestion, the % loss of total phenolics and anthocyanins of polysaccharide and anthocyanin complexes were shown here for pectin (16.00 ± 1.5; 47.13 ± 0.5), inulin (58.95 ± 0.1; 80.67 ± 0.09), starch (74.31 ± 3.0; 89.81 ± 0.03), cellulose (76.82 ± 1.5; 72.11 ± 0.1) and mixture (50.32 ± 3.2; 69.90 ± 0.6). Pectin exhibited the best complexation efficiency among different polysaccharides. Caco-2 and HT29-MTX cocultures treated with lipopolysaccharide (LPS) and FITC were used to measure the permeability. Pectin-anthocyanin complex effectively ameliorated LPS-induced increase in cell permeability followed by anthocyanin complexes with the mixture, cellulose, starch, and inulin, respectively. Conclusions These results suggest that pectin is the best candidate for the complexation with anthocyanins for improved gastrointestinal stability and barrier function. Funding Sources USDA-NIFA awards 2016–67,017-29,285 and 2019–67,017-29,258.

Optimization of spray drying condition and wall material composition for myrtle extract powder using response surface methodology

This study was aimed to optimize spray drying conditions (inlet air temperature: 120–180 °C) and wall material composition (maltodextrin (MD), gum Arabic (AG)) to obtain the powder of myrtle berry (Myrtus communis L.) extract having higher biological activities. Response surface methodology was used where maximum drying yield and minimum loss of total phenolics were dependent variables. Two optimum conditions were obtained: (1) a composition of 5.75 g maltodextrin/100 mL extract and 9.25 g gum Arabic/100 mL extract as wall materials at 180 °C inlet air temperature; (2) a composition of 3.75 g maltodextrin/100 mL extract and 11.25 g gum Arabic/100 mL extract as wall materials at 120 °C inlet air temperature. The second one was preferred due to lower phenolic losses. Optimum drying conditions provided the highest powder yield (39.89%) and least phenolic loss (16.95%). The bulk and tapped densities of the obtained powders were determined as 375.6 ± 9.7 and 609.6 ± 22.5 kg/m3, respectively. Total phenolics content and antioxidant activity of the obtained powder were found as 0.78 ± 0.01 g gallic acid equivalent (GAE)/100 g dry basic (db) and 1.69 ± 0.07 g trolox equivalent antioxidant activity (TEAC)/100g db, respectively. Particle size distribution was found between 0.69 and 16.175 µm. Epicatechin-3-0-gallate (EGC) and myricetin were main phenolics while D-limonene and α-pinene were main volatile components in the crude extract as well as in final powder product.

Application of induced electric field for inner heating of kiwifruit juice and its analysis

Kiwifruit juice is a popular liquid food with a large consumption. It usually needs high temperature sterilization before packaging and selling. Alternating magnetic field can produce alternating induced electric field, then a thermal effect is triggered. This study aims to explore the inner heating of kiwifruit juice via induced electric field and its impact on the physicochemical properties. Meanwhile, ultra-high temperature instantaneous sterilization (121°C, 5 s), and conventional heat treatment (93°C, 2 min) were conducted as controls, then effects were compared between these treatments. The results showed that the bacterial, mold and yeast colonies were completely eliminated, polyphenol oxidase activity decreased by 94.8%, and peroxidase activity decreased by 92.7%, at 1800 V and 6 mL/min. The induced electric field treatment and ultra-high temperature instantaneous sterilization had no significant effect on pH and titratable acid ( P ≥ 0.05). Conventional heat treatment increased soluble solid content by 5.3%. The induced electric field treatment resulted in the closest color and browning index to the fresh juice owing to moderate thermal effect. It also demonstrated minimal loss on total phenols and flavonoids contents after induced electric field treatment (7.1% and 2.7%, respectively). The heating effect caused by induced electric field has great application potential for the treatment of fruit juice. • Induced electric field was utilized for direct heating of kiwifruit juice. • Contact-less thermal effect and temperature rise on kiwifruit juice was evaluated. • The microbe and enzyme could be inactivated within 7.7 s via continuous-flow treatment. • The minimal loss of total phenols and flavonoid was achieved via induced electric field.

Stability of bioactive compounds and in vitro gastrointestinal digestion of red beetroot jam: Effect of processing and storage

The stability of total phenolics, flavonoids and betalains, as well as antioxidant capacity of red beetroot during jam processing, storage and in vitro gastrointestinal digestion were measured using spectrophotometry. Results suggested that jam processing led to a significant reduction of total phenolics (13.8%), betalains (56.3%) and antioxidant capacity (13.2–28.2%), but a significant increase of total flavonoids (99.3%). After storage at 4 °C for 90 days, the losses of total phenolics, flavonoids, betalains and antioxidant capacity were 33.9, 10.6, 7.9 and 9.7–35.7%, respectively. In addition, jam processing improved the bioaccessibility of total phenolics, flavonoids, betalains and antioxidant capacity using in vitro simulated gastrointestinal digestion analysis. The results of this study suggested that the main bioactive compounds of red beetroot including phenolics, flavonoids and betalains, could be partially preserved during jam processing and storage, with higher levels of bioaccessibility. Therefore, the red beetroot was a promising material for the development of functional foods.

Effect of ethanol pretreatment on melon convective drying

The aim of this study was to evaluate the effectiveness of the use of ethanol, ultrasound and/or vacuum as a pretreatment to melon drying. Eight types of pretreatments were performed in which samples were immersed in ethanol solutions with different concentrations (50% and 100%) using four treatment conditions: immersion, immersion with ultrasound (US), with vacuum (VC) and with ultrasound and vacuum (USVC). Drying was performed at 60 °C and five different semi-theoretical drying mathematical models were examined to characterize the drying curves, and quality analyses were carried out. The condition that obtained the lower drying time was using the US pretreatment in 100% ethanol solution. Drying caused a diminution of bioactive compounds and influenced color parameters. However, the samples immersed in 50% ethanol solution and dried obtained minor losses of total phenolics, total carotenoids, and ascorbic acid contents.

Functional Properties and Acceptability of Ice Soy Milk Fortified with Papaya or Kiwiالخصائص الوظیفیة ودرجه التقبل لمثلج لبن فول الصویا المدعم بالکیوى او الباباظ

Lactose-free products are still not suitable for people who suffer from food allergy. Therefore, the present investigation was carried out to enhance the functional properties of ice soy milk fortified with different percentage of fresh kiwi (FK) and papaya (FP) at (5%, 10% and 15%) as well as a powder (KP and PP) at 0.5%, 1% and 1.5%. Fortifications led to an increment of the total flavonoids content to 40% with FP and 69% with FK, total phenols (20% and 35%) and tannins (36% and 60%) in FK and FP ice soy milk compared to control, respectively. Using citric acid before drying led to a loss of total phenols, flavonoids and tannins content by only 13%, 16% and 27%, respectively. Carotenoids were found to be at the highest level in ice soy milk with 15%FP in comparison to PP1.5% and FK15%. On the other hand, incorporation of kiwi or papaya powder causes decrements in overrun value. Ice soy milks were considered microbiologically safe. A high positive significant correlations were observed between ice soy milk bioactive components and DPPH, TP(r=0.638,P<0.01), tannins(r=0.673,P<0.01) and TF(r=0.727,P<0.01), as well as it had a negative significant correlation with NEB(r=-0.823,P<0.01) and yellow flavonoid(r=-0.829,P<0.01). The ‘b’ value was increment with increased percentage of fresh fruits and had a significant strong correlation with carotenoids(r=0.943,P<0.01), TP(r=0.871,P<0.01) and tannin(r=0.818,P<0.01). Ice soy milk produced with FK 15% as well as FP 10% could be used as a healthy acceptable frozen product especially people who suffer from lactose intolerance and food allergy syndromes.

Loss of total phenols from leaf litter of two shrub species: dual responses to alpine forest gap disturbance during winter and the growing season

AbstractAimsAlpine forest gaps can control understory ecosystem processes by manipulating hydrothermal dynamics. Here, we aimed to test the role of alpine forest gap disturbance on total phenol loss (TPL) from the decomposing litter of two typical shrub species (willow, Salix paraplesia Schneid., and bamboo, Fargesia nitida (Mitford) Keng f.).MethodsWe conducted a field litterbag experiment within a representative fir (Abies faxoniana Rehd.) forest based on ‘gap openness treatments’ (plot positions in the gap included the gap center south, gap center north, canopy edge, expanded edge and closed canopy). The TPL rate and litter surface microbial abundance (fungi and bacteria) of the two shrub species were measured during the following periods over 2 years: snow formation (SF), snow cover (SC), snow melting (ST), the early growing season (EG) and the late growing season (LG).Important FindingsAt the end of the study, we found that snow cover depth, freeze–thaw cycle frequency and the fungal copies g−1 to bacterial copies g−1 ratio had significant effects on litter TPL. The abundances of fungi and bacteria decreased from the gap center to the closed canopy during the SF, SC, ST and LG periods and showed the opposite trend during the EG periods. The rate of TPL among plot positions closely followed the same trend as microbial abundance during the first year of incubation. In addition, both species had higher rates of TPL in the gap center than at other positions during the first winter, first year and entire 2-year period. These findings suggest that alpine forest gap formation accelerates litter TPL, although litter TPL exhibits dual responses to gap disturbance during specific critical periods. In conclusion, reduced snow cover depth and duration during winter warming under projected climate change scenarios or as gaps vanish may slow litter TPL in alpine biomes.

A novel, green cloud point extraction and separation of phenols and flavonoids from pomegranate peel: An optimization study using RCCD

Cloud point extraction (CPE) is one of the novel; environment-friendly; energy; time and cost-effective extraction technique. Therefore, in the present work preconcentration and separation of bioactive compounds from pomegranate peel, a major waste of the pomegranate processing industry was carried out using CPE. CPE works on the principle of entrapping the hydrophobic bioactive compound in the micelle. Surfactant concentration (5–11%), pH (4–8), temperature (30–60 °C), and salt concentration (4–12%) optimization was carried out to separate total phenols and flavonoids with maximum recovery (%R), partition coefficient (Ks/a), fraction concentration (fc), and minimum loss (%L) using the rotatable central composite design (RCCD). The optimum levels were 8.22% surfactant (Triton X-114), 4% salt (NaCl) at temperature of 36.80 °C and pH 4 which resulted in 95% recovery, 14.59 Ks/a, 0.95 fc and 5.27% loss of total phenols with the maximum desirability about 0.846. While in the case of total flavonoids at 8.27% Triton X-114 at pH 5.07/34.30 °C and 4.06% NaCl resulted, 98% recovery, 9.71 Ks/a, 1.01 fc, and 2% loss with 0.842 desirability. The total yield obtained for total phenols was 205.2 mg of GAE/g while for total flavonoids it was 60.05 mg of QE/g of pomegranate peel powder. Therefore, it can be concluded that this method can be successfully applied in the extraction of bioactive from any food systems for clean and green extractives label.

Changes in Quality Attributes Related to Browning during Storage of Litchi Juice Fermented by Lactobacillus

Litchi juice fermented by Lactobacillus casei was heated (95&amp;deg;C, 1 min) and stored in a dark place at 25&amp;deg;C. Changes in quality attributes (color, 5-hydroxymethylfurfural (5-HMF) phenolic compounds, antioxidant capacity, sugars, free amino acids, and others) related to browning in fermented litchi juice were investigated during the six months of storage. Noticeable visual changes due to browning were observed during storage of fermented litchi juice, especially in the upper part of the juice bottle, and the value of color difference (△E) increased to 7.12&amp;plusmn;0.04 after six months of storage. The 5-HMF content increased with the increase in storage time, which rose from 0 to 2.31&amp;plusmn;0.16 mg/L after six months of storage. Five soluble phenolic compounds (rutin, narcissoside, quercetin, kaempferol-rutinose-rhamnoside, and isorhamnetin-rutinose-rhamnoside) were identified in fermented litchi juice, none of which showed a significant decrease (P&amp;gt;0.05), whereas a tendency for total phenolic content to decrease was observed during storage of fermented litchi juice. Adding 0.3 g/L of sodium sulfite can inhibit the browning reaction in fermented litchi juice and decrease the formation of 5-HMF as well as the loss of total phenolics.

Delay of Postharvest Browning in Litchi Fruit by Melatonin via the Enhancing of Antioxidative Processes and Oxidation Repair.

Melatonin acts as a crucial signaling and antioxidant molecule with multiple physiological functions in organisms. To explore effects of exogenous melatonin on postharvest browning and its possible mechanisms in litchi fruit, 'Ziniangxi' litchi fruits were treated with an aqueous solution of melatonin at 0.4 mM and then stored at 25 °C for 8 days. The results revealed that melatonin strongly suppressed pericarp browning and delayed discoloration during storage. Melatonin treatment reduced relative membrane-leakage rate and inhibited the generation of superoxide radicals (O2-·), hydrogen peroxide (H2O2), and malondialdehyde (MDA). Melatonin treatment markedly promoted the accumulation of endogenous melatonin; delayed loss of total phenolics, flavonoids, and anthocyanins; and enhanced the activities of antioxidant enzymes, including superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2). By contrast, the activities of browning-related enzymes including polyphenoloxidase (PPO, EC 1.10.3.1) and peroxidase (POD, EC 1.11.1.7) were reduced. In addition, melatonin treatment up-regulated the expression of four genes encoding enzymes for repair of oxidized proteins, including LcMsrA1, LcMsrA2, LcMsrB1, and LcMsB2. These findings indicate that the delay of pericarp browning and senescence by melatonin in harvested litchi fruit could be attributed to the maintenance of redox homeostasis by the improvement of the antioxidant capacity and modulation of the repair of oxidatively damaged proteins.

Preserving quality of fresh walnuts using plant extracts

Fresh walnut kernel is considered as a way of walnut consumption, particularly in Asia, even though its market is less commercial than the dried kernel. There is a little knowledge about the storage of this commodity. Postharvest treatments including plant extracts either of Thymus vulgaris (ET) or walnut green husk (EWGH) in four concentrations (25, 50, 75 and 100 mg/L) and distilled water (as control) were assayed to increase fresh walnut kernel's shelf life at ambient temperature in the aqueous environment. Compared with untreated walnuts, the content of saturated fatty acids and linolenic was almost constant. Oleic acid concentration did not change considerably during storage in treated samples, while it was decreased in untreated kernels. The level of linoleic acid also decreased except for samples treated with the three higher EWGH concentrations. All treatments delayed lipid peroxidation and increment of acid value (AV). In addition, total antioxidant activity (TAA) and total phenolics (TPs) losses were observed by advanced time. After 28 days, the greatest losses of TAA and TPs were observed in untreated kernels. These results illustrate that ET and EWGH have potential to maintain fresh walnut quality during storage at 25 °C in the aqueous environment for 28 d.

Effect of Cooking and Reconstitution Methods on the Loss of Bioactive Compounds in Pigmented and Unpigmented Potatoes

Total phenolics, anthocyanins and antioxidant capacity of five coloured/pigmented (AR2009-10, Adirondack Red, Adirondack Blue, Congo, and POROIPG22-1) and two unpigmented potato genotypes (“Anuschka” and “Russet Burbank”) were assessed in fresh (with and without skin) and commercially processed/cooked/reconstituted products. Ascorbate profiles of the seven genotypes also were investigated using fresh tuber/tissue only. The results showed that genotypes greatly varied in their contents of bioactive compounds. Ascorbate profiles of the genotypes were not associated to any particular flesh colour/pigment. However, the pigmented potatoes had 1.5 to 2.5 times more the phenolics, 2 to 3 times more antioxidant capacity and higher levels of anthocyanins (13.98 to 38.57 mg C3GE-100g FW) compared to unpigmented genotypes. No anthocyanins were detected in the unpigmented potatoes. Significant losses of total phenolics, anthocyanins and total antioxidant capacity were found during peeling (18% - 23%), blanching process (40% - 60%) and further cooking/ reconstitution (7% - 12%) with no prominent genotype differences. Together, 65 to 90% of these bioactive compounds were lost during processing. The results suggested that pigmented potatoes contained higher amounts of total phenolics and anthocyanins and blanching step took away the most of the original bioactive compounds.

Forest Gaps Alter the Total Phenol Dynamics in Decomposing Litter in an Alpine Fir Forest.

The total phenol content in decomposing litter not only acts as a crucial litter quality indicator, but is also closely related to litter humification due to its tight absorption to clay particles. However, limited attention has been focused on the total phenol dynamics in foliar litter in relation to forest gaps. Here, the foliar litter of six representative tree species was incubated on the forest floor from the gap center to the closed canopy of an alpine Minjiang fir (Abies faxoniana) forest in the upper reaches of the Yangtze River and eastern Tibetan Plateau. The dynamics of total phenol concentration in the incubated litter was measured from November 2012 to October 2014. Over two-year incubation, 78.22% to 94.06% of total phenols were lost from the foliar litter, but 52.08% to 86.41% of this occurred in the first year. Forest gaps accelerated the loss of total phenols in the foliar litter in the winter, although they inhibited the loss of total phenols during the growing season in the first year. In comparison with the effects of forest gaps, the variations of litter quality among different species were much stronger on the dynamics of total phenols in the second year. Overall, the loss of total phenols in the foliar litter was slightly higher in both the canopy gap and the expanded gap than in the gap center and under the closed canopy. The results suggest that the predicted decline in snow cover resulting from winter warming or vanishing gaps caused by forest regeneration will retard the loss of total phenol content in the foliar litter of alpine forest ecosystems, especially in the first decomposition year.

Phenolic Compounds and Their Fates In Tropical Lepidopteran Larvae: Modifications In Alkaline Conditions.

Lepidopteran larvae encounter a variety of phenolic compounds while consuming their host plants. Some phenolics may oxidize under alkaline conditions prevailing in the larval guts, and the oxidation products may cause oxidative stress to the larvae. In this study, we aimed to find new ways to predict how phenolic compounds may be modified in the guts of herbivorous larvae. To do so, we studied the ease of oxidation of phenolic compounds from 12 tropical tree species. The leaf extracts were incubated in vitro in alkaline conditions, and the loss of total phenolics during incubation was used to estimate the oxidizability of extracts. The phenolic profiles of the leaf extracts before and after incubation were compared, revealing that some phenolic compounds were depleted during incubation. The leaves of the 12 tree species were each fed to 12 species of lepidopteran larvae that naturally feed on these trees. The phenolic profiles of larval frass were compared to those of in vitro incubated leaf extracts. These comparisons showed that the phenolic profiles of alkali-treated samples and frass samples were similar in many cases. This suggested that certain phenolics, such as ellagitannins, proanthocyanidins, and galloylquinic acid derivatives were modified by the alkaline pH of the larval gut. In other cases, the chromatographic profiles of frass and in vitro incubated leaf extracts were not similar, and new modifications of phenolics were detected in the frass. We conclude that the actual fates of phenolics in vivo are often more complicated than can be predicted by a simple in vitro method.

Effect of solution pH and activated carbon dosage on the decolourization ability, nitrogen components and antioxidant activity of peanut meal hydrolysate

SummaryActivated carbon was used to remove the colour of peanut meal hydrolysate. Effects of solution pH and activated carbon dosages on the decolourization efficiency, nitrogen components and antioxidant activity of the hydrolysate were investigated. The results showed that the colour and the undigested protein or large peptides could be removed efficiently under acidic condition (pH 2.0–4.0), while less small peptides were adsorbed under this condition. Among these total amino acids (AAs), the loss of aromatic AA (Tyr and Phe) was the largest regardless of the solution pH. Greater loss of acidic AA (Glu and Asp) was observed under acidic condition, while the loss of basic AA (His, Lys and Arg) followed the opposite trend. The antioxidant activity of the hydrolysate was also reduced after decolourization, which was likely due to the loss of total phenolics and peptides containing aromatic and/or acidic AA.

The effects of bagging and debagging on external fruit quality, metabolites, and the expression of anthocyanin biosynthetic genes in ‘Jonagold’ apple (Malus domestica Borkh.)

‘Jonagold’ apple (Malus domestica Borkh.) was used to determine the effects of bagging and debagging on fruit external and internal qualities, as well as transcript levels for key genes involved in anthocyanin synthesis. Fruits from three treatments – control (never bagged), always bagged, or debagged – were harvested at 0h, 6h, 30h, 3 d, 7 d, and 14 d after certain bags were removed. Peel and flesh tissues were sampled separately. Compared with the control, bagged fruit were yellowish, and had higher scores for lightness and hue angle, lower values for chroma, and the lowest concentration of anthocyanins. Fruit firmness was slightly increased by bagging treatment, whereas soluble solids content (SSC) was decreased. Compared with the control, bagged fruit had more starch, glucose, and galactose, but less of the other sugars and sugar alcohols. The concentrations of fructose and total non-structural carbohydrates were not obviously affected by bagging. Although the malic acid concentration was not influenced by bagging, other acids were either increased (quinic, shikimic, and citric) or decreased (ascorbic). The concentration of total organic acids did not show large difference among three treatments except that it tended to be lower at 14 DABR (days after bag removal). Phenolic compounds, especially flavonols in the peel, were severely inhibited, but their concentrations were increased by re-exposure to sunlight after bag removal. The debagging treatment led to up-regulation of the expression of MdMYB10 and seven structural genes involved in anthocyanin biosynthesis, and subsequent accumulation of anthocysnins. However, the peel of debagged fruit still have lower levels of anthocyanins and other phenolic compounds at harvest, although bag removal made up for the loss of total phenolics in the flesh.