Condensed tannins-Their content in plant foods, changes during processing, antioxidant and biological activities.

Condensed tannins are considered nutritionally undesirable, because they precipitate proteins, inhibit digestive enzymes, and can affect the absorption of vitamins and minerals. From the consumer's point of view, they impart astringency to foods. Yet, they are viewed as a double-edged sword, since they possess antioxidant and anti-inflammatory activities. Intake of a small quantity of the right kind of tannins may in fact be beneficial to human health. This chapter reports on the chemical structure of condensed tannins, their content in plants and food of plant origin, how they are extracted, and methods for their determination. A description of the effects of processing on condensed tannins is discussed and includes soaking, dehulling, thermal processing (i.e., cooking, boiling, autoclaving, extrusion), and germination. The astringency of condensed tannins is described in relation to their interactions with proteins. Finally, details about the biological properties of condensed tannins, including their antimicrobial, anti-inflammatory, anticancer, anti-diabetic, and anti-obesity activities, are reviewed.

Lentils (Lens culinaris Medik) as a Source of Phenolic Compounds - their Content, Changes during Processing, Antioxidant and Biological Activities.

While often recognized as a good plant protein source and a rich source of essential nutrients including folate, iron, manganese and phosphorus, lentils (Lens culinaris L.) also contain healthful bioactive compounds. They possess a number of phenolic compounds including phenolic acids, flavonoids such as flavan- 3-ols, flavonols and anthocyanins, proanthocyanidins, as well as saponins and phytic acid. This review provides a summary of the types and levels of phenolic compounds found in the cotyledon of lentils as well as their seed coats. The values define broad ranges due to varied cultivars, horticultural practices, climatic conditions during lentil development, and the different phenolic extraction approaches employed. The prepared lentil extracts were found to possess marked antioxidant activity, as assessed by in vitro assays, with the results clearly indicating that the endogenous phenolic compounds dictated this activity. Processing of raw lentils in the forms of cooking, germination and fermentation was determined to affect the phenolics' contents: phenolic content of some lentils decreased while those of others increased, most likely due to the release of bound phenolics from the plant wall matrix. Finally, a summary of some of the positive biological activities observed for lentil extracts from cell culture and animal studies is given.

Examining the Performance of Two Extraction Solvent Systems on Phenolic Constituents from U.S. Southeastern Blackberries.

Two common extraction solvent systems, namely acidified aqueous methanol and acidified aqueous acetone, were used to extract blackberry phenolics, and the antioxidant properties of the recovered extracts were compared. The crude extracts were fractionated into low- and high-molecular-weight phenolics by Sephadex LH-20 column chromatography. The hydrophilic-oxygen radical absorbance capacity (H-ORACFL), ferric reducing antioxidant power (FRAP), and the cellular antioxidant activity (CAA) assays were employed as indices to assess antioxidant capacity of the extracts and their respective fractions. The methanolic solvent system displayed a greater efficiency at extracting anthocyanin and flavonol constituents from the blackberries, while the acetonic solvent system was better at extracting flavan-3-ols and tannins. Anthocyanins were the dominant phenolic class found in the blackberries with 138.7 ± 9.8 mg C3G eq./100 g f.w. when using methanol as the extractant and 114.6 ± 3.4 mg C3G eq./100 g f.w. when using acetone. In terms of overall antioxidant capacity of blackberry phenolics, the acetonic solvent system was superior. Though present only as a small percentage of the total phenolics in each crude extract, the flavan-3-ols (42.37 ± 2.44 and 51.44 ± 3.15 mg/100 g f.w. in MLF and ALF, respectively) and ellagitannins (5.15 ± 0.78 and 9.31 ± 0.63 mg/100 g f.w. in MHF and AHF, respectively) appear to account for the differences in the observed antioxidant activity between the two solvent systems.

Variation in the terminology and methodologies applied to the analysis of water holding capacity in meat research.

Studies examining meat quality variation, possibly resulting from animal physiology, processing, or ingredient additions, are likely to include at least one measure of water holding capacity (WHC). Methods for evaluating WHC can be classified as direct or indirect. Direct methods either gauge natural release of fluids from muscle or require the application of force to express water. The indirect methods do not actually measure WHC. They attempt to separate meat into two or three categories based on predictions of direct method results: the extreme of high and low WHC and an optional 'normal' group. Considerable statistical analyses are required to generate these predictive models. Presently, there are inconsistent terms (e.g., water holding, WHC, water binding, water binding potential/capacity) used to describe WHC and no standardized techniques recommended to evaluate it. To ensure that results can be compared across different laboratories, a better consensus must be reached in how these terms are employed and how this critical parameter is determined.

Effect of konjac glucomannan on metabolites in the stomach, small intestine and large intestine of constipated mice and prediction of the KEGG pathway.

The occurrence of constipation involves the whole gastrointestinal tract. Konjac glucomannan (KGM) has been clinically proven to alleviate constipation, but its mechanism has not been fully understood. The present study aimed to investigate the excretion-promoting effect of KGM on constipated mice and the underlying molecular mechanism. In this study, the UHPLC-QE orbitrap/MS method was used to determine the metabolic phenotypes of total gastrointestinal segments (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) in constipated mice treated with KGM. The results showed that KGM improved the fecal water content, body weight growth rate, and serum gastrointestinal regulation related peptide levels. The metabolomics results revealed the decreased levels of amino acids, cholines, deoxycholic acid, arachidonic acid, thiamine and the increased levels of indoxyl sulfate, histamine, linoelaidic acid etc. The KEGG pathway analysis indicated that the relaxation effect of KGM supplementation was most likely driven by modulating the expression levels of various key factors involved in biosynthesis of amino acid (i.e., phenylalanine, tyrosine and tryptophan), linoleic acid metabolism, biosynthesis of secondary metabolites, and arachidonic acid metabolism signalling pathways. The results indicated that KGM alleviates constipation by regulating potential metabolite markers and metabolic pathways in different gastrointestinal segments.

Prevention of loperamide induced constipation in mice by KGM and the mechanisms of different gastrointestinal tract microbiota regulation.

Constipation is one of the most prevalent gastrointestinal tract diseases. Konjac glucomannan (KGM) dietotherapy can effectively relieve the clinical symptoms of patients with constipation. However, the causal relationship among KGM, constipation and different gastrointestinal microbiome (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) remains poorly understood. In this study, constipated mice were treated with KGM (75, 150, 300 mg/kg bw). Results showed that KGM treatment improved the general physiological state, fecal character, small intestinal propulsive rate, gastric emptying rate, MTL and AchE activities, ET-1, 5-HT, and NO levels, and SCFA concentrations. KGM in the diets of constipated mice reduced the diversity of St and S microbiota, while increased those in the L. The KGM intervention regulated the microbiota profile, which afterwards was closer to the normal mouse group: confirmation was provided by different changes of bacteria like Lactobacillus, Bifidobacterium and Allobaculum spp et al.

Protection of natural antioxidants against low-density lipoprotein oxidation.

This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.

Tree Nuts and Peanuts as a Source of Natural Antioxidants in our Daily Diet.

Tree nuts and peanuts are healthy foods with a proven track record of helping to reduce the incidence of chronic diseases, most notably cardiovascular disease. At the point of consumption, all nuts contain low moisture and ≥ 50% lipid contents, but this is where similarities end. The levels of key nutrients and bioactives including vitamin C, vitamin E, L-arginine, minerals (such as selenium and zinc), and phenolics can differ markedly. Distinctions in the types and quantities of phenolic constituents for tree nut species, as well as the impact of digestion, will affect the nuts' antioxidant potential in vivo. This work provides some insight into the different types of phenolics found in tree nuts and peanuts, the antioxidant potential of their phenolic extracts using in vitro chemical assays, the effect of thermal processing on the stability of the nuts' endogenous phenolics, and the impact on biomarkers of human health arising from randomized clinical trials. Key biomarkers include measures in the reduction of LDL oxidation as well as increases in the levels of vitamin E and selected phenolic compounds in blood plasma postprandially from those of baseline.

The cellular antioxidant and anti-glycation capacities of phenolics from Georgia peaches.

Plant-based polyphenolics have been reported to bestow health benefits when consumed, which are partially ascribed to their antioxidant activity. Yet, many current in vitro chemical assays to characterize antioxidant potential do not truly reflect the physiological properties of food antioxidants in vivo. The present study employed biological approaches, including a cellular antioxidant activity (CAA) and protein glycation assays, to offer an improved picture of antioxidant potential of phenolic extracts from Georgia peach cultivars. The phenolic extracts from two peach varieties, showing contrasting antioxidant capacities according to hydrophilic-oxygen radical absorbance capacity (H-ORACFL) and ferric reducing antioxidant power (FRAP) assays, exhibited significant differences in two biological tests when the assays were performed on a fresh weight basis. The procyanidins fraction displayed notable antioxidant capacity, when compared to other phenolic classes in the peach extract, in these two biologically relevant assays.

Quantitation of Inositol Phosphates by HPLC-ESI-MS.

The coupling of anion exchange high-pressure liquid chromatography (HPLC) with electrospray ionization mass spectrometry (ESI-MS) allows for the simultaneous detection of the six forms of inositol phosphate (InsP). Here we describe a rapid quantitative analysis of InsPs by HPLC-ESI-MS, which can be applied to a wide array of sample types. With this method, InsPs could be separated and detected within 20 min of sample injection. The detection limit was as low as 25 pmol (i.e., ca. 2 nmol/g sample) for each type of InsP, which is particularly important for analytes that are often present at low abundance in nature.

Natural antioxidants of plant origin.

Interest in the content of natural antioxidants in plant-based foods can be from the human health perspective, in terms of how these compounds might help promote one's health and wellness, or from the storage point-of-view, as the endogenous antioxidant constituents aid to extend a foodstuff's shelf-life. This chapter reports essential information about the mechanism of antioxidant action and methods employed for determination of their activity, classes of phenolic compounds (phenolic acids, flavonoids, lignans, stilbenes, tannins), sources of plant antioxidants (oil seeds, cereals, legumes, plants of the Lamiaceae family, tea and coffee, tree nuts, fruits, and berries), extraction strategies of phenolic compounds from plant material, and the influence of processing and storage on the content of natural antioxidants in foods and their antioxidant activity. Thermal processing, if not releasing bound phenolics from the structural matrices of the food, tends to decrease the antioxidant potential or, in the best case scenario, has no significant negative impact. Gentler sterilization processes such as high-pressure processing tend to better retain the antioxidant potential of a foodstuff than thermal treatments such as steaming, boiling, or frying. The impact of processing can be assessed by determining the antioxidant potential of foodstuffs either at the point of formulation or after different periods of storage under specified conditions.

Cellular evaluation of the antioxidant activity of U.S. Pecans [Carya illinoinensis (Wangenh.) K. Koch].

Clinical trials show an inverse relationship between the consumption of antioxidant-rich tree nuts and the development of chronic diseases. This study examined antioxidant efficacy of U.S. pecans using a modified cellular antioxidant activity (CAA) assay with comparisons to data from in vitro antioxidant assays (hydrophilic-oxygen radical absorbance capacity {H-ORACFL} and ferric reducing antioxidant power {FRAP}). Crude phenolic extracts from both raw and roasted pecans were analyzed. In the CAA assay, pecan phenolics were taken up by human colorectal adenocarcinoma (Caco-2) cells and bestowed CAA, determined by monitoring the fluorescence of 2',7'-dichlorofluorescein. Phenolics (25-100 µg/mL) demonstrated a reduction in fluorescence by 37-69% for raw and 26-68% for roasted pecans. The primary active phenolic constituents were determined by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) to be epi(catechin) dimers and trimers. These oligomeric procyanidins, ranging in size from 560 to 840 g/mol appear to be small enough for cellular uptake, showing pecans are an effective antioxidant in biological systems, regardless of roasting.

Tart cherry consumption with or without prior exercise increases antioxidant capacity and decreases triglyceride levels following a high-fat meal.

Exercise and high-phytonutrient foods may lower oxidative stress and increase antioxidant levels, which could combat the negative effects associated with a high-fat (HF) meal. The objective of this study is to test the effects of Montmorency tart cherry (Prunus cerasus L.) consumption, with or without aerobic exercise, on antioxidant responses to an HF meal. Twelve normal-weight men (aged 22 ± 3 years), participated in a randomized crossover design comprising 4 trials: (i) HF meal with Montmorency tart cherry consumption (MC), (ii) HF meal with placebo (P), (iii) exercise prior to HF meal with MC (E+MC), and (iv) exercise prior to HF meal with P (E+P). The HF meal contained 60 g of fat and was consumed with MC or P. For exercise trials, a 30-min bout of submaximal treadmill exercise was performed the afternoon prior to HF meal consumption. Antioxidant capacity and triglycerides (TG) levels were measured at baseline and at 1, 2, and 3 h postprandially. Postprandial antioxidant capacity as assessed by oxygen radical absorbance capacity was significantly higher after MC and E+MC compared with E+P (incremental area under the curve (iAUC): 2.95 ± 2.19 and 4.87 ± 1.45 vs. -1.02 ± 1.72 mmol Trolox equivalents/L for MC and E+MC vs. E+P, respectively; p < 0.01). Postprandial TG levels were significantly lower after E+MC compared with P (iAUC: 58.99 ± 19.46 vs. 107.46 ± 22.66 mmol Trolox equivalents/L for E+MC vs. P, respectively; p < 0.05). These results indicate that MC consumption alone, and in combination with prior exercise, leads to greater antioxidant capacity following an HF meal compared with prior exercise with placebo. Further, MC consumption with prior exercise led to more favorable postprandial TG levels compared with placebo.

Characterizing the phenolic constituents and antioxidant capacity of Georgia peaches.

Acetonic crude phenolic extracts of six Georgia peach cultivars were prepared and separated into low- and high-molecular-weight (LMW and HMW) fractions by Sephadex LH-20 column chromatography. Further characterization via RP-HPLC-ESI-MS identified the main phenolics as hydroxycinnamates, (+)-catechin, and proanthocyanidins with degrees of polymerization up to seven. The LMW phenolics of the commercial cultivar, 'July Prince', were further chromatographed and examined by RP-HPLC-ESI-MS. Derivatives of phenolic acids and flavan-3-ols, along with eriodictyol and quercetin diglycosides, were identified. Antioxidant capacities of the LMW and HMW fractions were determined using in vitro assays. H-ORACFL and FRAP assays gave values of 872 to 2428 µmol Trolox eq./100 g f.w. and 309 to 432 µmol Fe2+ eq./100 g f.w., respectively. The total phenolics content (TPC) was also measured; correlations between TPCs and antioxidant assays indicated that the HMW fractions of peach extracts were major contributors to the antioxidant capacity of the cultivars analyzed.

A 5-day high-fat diet rich in cottonseed oil improves cholesterol profiles and triglycerides compared to olive oil in healthy men.

Modifying dietary fat composition is important for minimizing cardiovascular disease risk. The purpose of this study was to determine the effects of a 5-day, high-fat diet rich in cottonseed oil (CSO) or olive oil (OO) on lipid profiles. Based on previous human and animal models, we hypothesized that the CSO-rich diet would lead to lower fasting and postprandial lipid levels, whereas the OO-rich diet would not significantly change lipid levels in 5 days. Fifteen normal-weight men completed a randomized crossover design with 2 controlled feeding trials (3-day lead-in diet, prediet visit, 5-day CSO- or OO-rich diet, postdiet visit). The 5-day diets (50% fat) were rich in either CSO or OO. At pre- and postdiet visits, subjects consumed test meals rich in the oil that coincided with their 5-day diet, and blood draws were performed. Fasting total cholesterol, low-density lipoprotein cholesterol, and triglycerides (TG) were lower following CSO diet intervention (total cholesterol: 148.40 ±â€¯6.39 to 135.93 ±â€¯6.31 mg/dL; low-density lipoprotein cholesterol: 92.20 ±â€¯5.57 to 78.13 ±â€¯5.60 mg/dL; TG: 80.11 ±â€¯4.91 to 56.37 ±â€¯5.46 mg/dL for pre- to postdiet, respectively; P < .05). High-density lipoprotein cholesterol increased following CSO diet intervention (46.67 ±â€¯2.41 to 50.24 ±â€¯2.20 mg/dL for pre- to postdiet, respectively; P < .05). Postprandial TGs were lower following CSO diet (area under the curve of 954.28 ±â€¯56.90 vs 722.16 ±â€¯56.15 mg/dL/8 h for pre- vs postdiet, respectively; P < .01). No changes in blood lipids were found following OO diet. A 5-day CSO-rich diet led to improvements in cholesterol and TGs, whereas no changes were observed with an OO-rich diet.

Characterization of the Volatile Compounds in Raw and Roasted Georgia Pecans by HS-SPME-GC-MS.

Volatile compounds are responsible for the characteristic aroma of raw and roasted pecans. Yet, much is unknown about the specific effects of roasting on pecan volatiles. In this study, the volatiles of raw "Desirable" pecans from Georgia and 3 roasted pecan samples (175 °C for 5, 10, and 15 min) were determined by HS-SPME coupled to GC-MS using stable deuterium-labeled volatiles as internal standards for quantitation. As expected, roasting markedly impacted the volatile profile of pecans: a total of 63 flavor-active compounds were identified in roasted samples, including 9 compounds not detected in raw "Desirable" pecans. Pyrazines, notable indicators of the Maillard reaction, were found only in roasted samples and demonstrated continual increases throughout observed roasting times. Furthermore, it was noted that hydrocarbon derivatives showed substantial increases with roasting, likely a result of the degradation of nonvolatile lipids. The observed changes correspond well to prior sensory investigations concerning the impact of roasting on pecan flavor, and explain increases in intensity for roasted, nutty, buttery, and sweet sensory traits. PRACTICAL APPLICATION: The results of this study document the volatile constituents generated during the roasting of pecans, and this may help formulators, who are trying to develop natural and artificial pecan flavors in new food products.

Practical use of natural antioxidants in meat products in the U.S.: A review.

Historically, meat and poultry processors in the U.S. have relied on the use of synthetic antioxidants like butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, and propyl gallate, as well as tocopherols to prevent lipid and protein oxidation. There is a trend towards utilizing natural antioxidants as replacements for synthetic ones. Some processors are already using multi-functional ingredients, such as rosemary and oregano, approved for use as spices and natural flavors to curb oxidation. Yet, there are still other ingredients that have not been applied in this fashion. Spices and natural flavors can often be incorporated in products that have defined statements of identity or composition. Further, these ingredients allow the processor to transition to a clean label without compromising the shelf life and quality of the products. Spices and natural flavors may have higher minimum effective concentrations than their synthetic counterparts, but they will offer increased consumer acceptability, decreased potential health risks, and can often achieve the same degree of oxidation prevention.

Effects of Storage Conditions on Consumer and Chemical Assessments of Raw 'Nonpareil' Almonds Over a Two-Year Period.

Raw almonds are a major commodity, yet much is unknown about how storage conditions determine their shelf life. The storage stability, as measured by consumer assessments and chemical measures, of raw almonds was determined for samples stored in cardboard boxes and polypropylene packaging for 2 years at 4, 15, 25, and 35 °C, and at 50% and 65% relative humidity (RH). Samples stored in unlined cartons always failed (>25% rejection) before their counterparts stored in polypropylene bags under identical environmental conditions. Models determined that polypropylene packaging (as opposed to unlined cardboard cartons) extended the time until sample rejection by more than 7 months. Temperature and RH were both negatively associated with storage time until failure. Flavor was a greater contributor to consumer acceptability than texture or odor, while peroxide values and free fatty acids were of greater importance in predicting raw almond consumer quality than measures of conjugated dienes or 2-thiobarbituric acid-reactive substances. PRACTICAL APPLICATION: The results of this study will allow almond producers to determine packaging types and environmental storage conditions that provide shelf life of a specified time.

Modification of the cellular antioxidant activity (CAA) assay to study phenolic antioxidants in a Caco-2 cell line.

In vitro assays are widely used to analyze the antioxidant potential of compounds, but they cannot accurately predict antioxidant behavior in living systems. Cell-based assays, like the cellular antioxidant activity (CAA) assay, are gaining importance as they provide a biological perspective. When the CAA assay was employed to study phenolic antioxidants using hepatocarcinoma (HepG2) cells, quercetin showed antioxidant activity in HepG2 cells; 25 and 250µM quercetin reduced fluorescence by 17.1±0.9% and 58.6±2.4%, respectively. (+)-Catechin, a phenolic antioxidant present in many foods, bestowed virtually no CAA in HepG2 cells. When Caco-2 cells were employed, more robust antioxidant activity was observed; 50µM (+)-catechin and quercetin reduced fluorescence by 54.1±1.4% and 63.6±0.9%, respectively. Based on these results, likely due to differences in active membrane transport between the cell types, the Caco-2-based CAA assay appears to be a more appropriate method for the study of certain dietary phenolics.

Effect of packaging types and storage conditions on quality aspects of dried Thunbergia laurifolia leaves and degradation kinetics of bioactive compounds.

Thunbergia laurifolia leaves were dried by freeze drying (FD) and microwave heat pump dehumidified air drying (MHPD). The dried leaves were stored in polypropylene (PP) or aluminum laminated pouches (ALP) at 15, 25 or 35 °C and 60% RH. The samples were held for 180 days to observe changes in moisture content, color, total phenolics, antioxidant activity, catechin and caffeic acid. In general, samples in PP had a greater increase in moisture. Total phenolics content and ferric-reducing antioxidant power values increased for 120 days, then decreased thereafter. After 180 days, both FD and MHPD samples packaged in ALP and stored at 15 °C had the greatest total phenolics, antioxidant activity and bioactive compounds amongst the storage conditions. The first-order equation best described degradation behavior of catechin and caffeic acid for both drying technologies investigated.