Antioxidant Activity of a Red Lentil Extract and Its Fractions

Phenolic compounds were extracted from red lentil seeds using 80% (v/v) aqueous acetone. The crude extract was applied to a Sephadex LH-20 column. Fraction 1, consisting of sugars and low-molecular-weight phenolics, was eluted from the column by ethanol. Fraction 2, consisting of tannins, was obtained using acetone-water (1:1; v/v) as the mobile phase. Phenolic compounds present in the crude extract and its fractions demonstrated antioxidant and antiradical activities as revealed from studies using a β-carotene-linoleate model system, the total antioxidant activity (TAA) method, the DPPH radical-scavenging activity assay, and a reducing power evaluation. Results of these assays showed the highest values when tannins (fraction 2) were tested. For instance, the TAA of the tannin fraction was 5.85 μmol Trolox® eq./mg, whereas the crude extract and fraction 1 showed 0.68 and 0.33 μmol Trolox® eq./mg, respectively. The content of total phenolics in fraction 2 was the highest (290 mg/g); the tannin content, determined using the vanillin method and expressed as absorbance units at 500 nm per 1 g, was 129. There were 24 compounds identified in the crude extract using an HPLC-ESI-MS method: quercetin diglycoside, catechin, digallate procyanidin, and p-hydroxybenzoic were the dominant phenolics in the extract

Picture-Hanging Puzzles

We show how to hang a picture by wrapping rope around n nails, making a polynomial number of twists, such that the picture falls whenever any k out of the n nails get removed, and the picture remains hanging when fewer than k nails get removed. This construction makes for some fun mathematical magic performances. More generally, we characterize the possible Boolean functions characterizing when the picture falls in terms of which nails get removed as all monotone Boolean functions. This construction requires an exponential number of twists in the worst case, but exponential complexity is almost always necessary for general functions.Comment: 18 pages, 8 figures, 11 puzzles. Journal version of FUN 2012 pape

Antioxidant activity, total phenolics and flavonoids contents: should we ban in vitro screening methods?

As many studies are exploring the association between ingestion of bioactive compounds and decreased risk of non-communicable diseases, the scientific community continues to show considerable interest in these compounds. In addition, as many non-nutrients with putative health benefits are reducing agents, hydrogen donors, singlet oxygen quenchers or metal chelators, measurement of antioxidant activity using in vitro assays has become very popular over recent decades. Measuring concentrations of total phenolics, flavonoids, and other compound (sub)classes using UV/Vis spectrophotometry offers a rapid chemical index, but chromatographic techniques are necessary to establish structure-activity. For bioactive purposes, in vivo models are required or, at the very least, methods that employ distinct mechanisms of action (i.e., single electron transfer, transition metal chelating ability, and hydrogen atom transfer). In this regard, better understanding and application of in vitro screening methods should help design of future research studies on ‘bioactive compounds’

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

Separation of Ellagitannin-Rich Phenolics from U.S. Pecans and Chinese Hickory Nuts Using Fused-Core HPLC Columns and Their Characterization

U.S. pecans and Chinese hickory nuts possess a wide array of phenolic constituents with potential health benefits including phenolic acids and proanthocyanidins. Only limited information is available, however, on their compositions. The present study optimized the separation performance and characterized the low-molecular-weight phenolic fractions of these nuts with C18 and pentafluorophenyl (PFP) fused-core LC columns by employing a kinetic approach. Although both types of reversed-phase columns demonstrated similar performance in general, the PFP column furnished greater plate numbers and superior peak shapes for the low-molecular-weight fractions as well as overall separations of ellagic acid derivatives. The high-molecular-weight fraction of pecans, analyzed by a 3-μm HILIC column, possessed more proanthocyanidins than the Chinese hickory nuts with dimers and trimers (31.4 and 18.34 mg/g crude extract, respectively) being present at the greatest levels. Chinese hickory nuts had lower proanthocyanidin content but possessed tetramers and pentamers at 4.46 and 4.01 mg/g crude extract, respectively

Selected Nutrient Analyses of Fresh, Fresh-Stored, and Frozen Fruits and Vegetables

This two-year study compared the status of targeted nutrients in selected fresh and frozen fruits and vegetables. In addition, a novel third category was examined—a “fresh-stored” categorization intended to mimic typical consumer storage patterns of produce following purchase (five days of refrigeration). Broccoli, cauliflower, corn, green beans, green peas, spinach, blueberries, and strawberries of all three categories of freshness were analyzed for their concentrations of L-ascorbic acid (vitamin C), trans-β-carotene (provitamin A), and total folate. Analyses were performed in triplicate on representative samples using standardized analytical methods and included a quality control plan for each nutrient. In the majority of comparisons between nutrients within the categories of fresh, frozen, and “fresh-stored”, the findings showed no significant differences in assessed vitamin contents. In the cases of significant differences, frozen produce outperformed “fresh-stored” more frequently than “fresh-stored” outperformed frozen. When considering the refrigerated storage to which consumers may expose their fresh produce prior to consumption, the findings of this study do not support the common belief of consumers that fresh food has significantly greater nutritional value than its frozen counterpart

Phenol-Based Antioxidants and the in Vitro Methods Used for Their Assessment

Abstract: In recent years, much interest has been observed in the field of phenol-based antioxidants. As a result of this, many analytical methods have been developed for the purpose of the quantification of phenolic and polyphenolic antioxidant capacities in biological materials. Many of these methods have been altered for application toward the in vitro assessment of antioxidant activities in animal and human model systems as well as in vivo. Due to the varied applicability and usage, methods for the assessment of phenol antioxidant capacities have become so widespread that they are often misused. It is the intent of this work to review the chemistry behind the antioxidant activity of phenolics as well as summarize the many methods applicable for the measurement of in vitro phenolic antioxidant capacity

Update on the Methods for Monitoring UFA Oxidation in Food Products

Unsaturated fatty acids (UFAs) as well as natural food ingredients containing them are being added to food products more often. Unfortunately, UFAs are susceptible to oxidative degradation, and can therefore reduce the stability of a food matrix. The assessment of oxidation and stability of lipids has never been standardized, and has long included a variety of approaches. These techniques can differ greatly in the reactions/compounds being assessed, and therefore the eventual conclusions may be affected dramatically by selection of methodology. The aim of this review is to provide an update on the methods of historic and current use for the assessment of lipid stability in food products. Accelerated storage tests, assessment methods of lipid oxidation, and rapid indicators of stability are discussed in the contexts of their modern prominences, uses, and concerns

Modeling the Impact of Residual Fat-Soluble Vitamin (FSV) Contents on the Oxidative Stability of Commercially Refined Vegetable Oils

Fat-soluble vitamins (FSVs) may prevent or delay bulk lipid oxidation by exerting antioxidant action. However, literature data obtained from storage tests on commercial edible oils do not necessarily confirm a direct correlation between FSV contents of bulk oils and their measured oxidative stability. This, of course, may be predominantly due to their refining history, which can strip them of much of their FSV contents and/or standardize these values. The main goal of this study was to quantify the magnitude of the role of FSVs in hindering commercial edible lipid oxidation. Fatty acid composition and FSV content data were collected on a large mixed set of commercial vegetable oils devoid of added antioxidant stabilizers (n = 123) in order to establish baseline values for these constituents. Next, a random subset of these oils (n = 50) was then subjected to the oil stability index test (OSI at 120 °C), as well as accelerated storage testing over time (60 °C) whilst monitoring a host of classical methodologies used to monitor oxidation progress. A new aggregate parameter (i.e., a sum area under the lipid oxidation curves, or \u27All Area\u27) was introduced to better capture the total quantity of primary and secondary oxidation products accumulated in the samples tested over the storage period. Multivariate regression modeling was used to correlate the fatty acid composition of the samples with their oxidative stability data both including and excluding FSV contents in order to determine a magnitude for this relationship. As noted herein, the addition of FSV data improved the fitting of the model from R 2 Adj. 0.877 to 0.925 using OSI data alone and from R 2 Adj. 0.938 to 0.960 using the \u27All Area\u27 parameter. Correlations between specific FSVs and fatty acid compositional parameters exhibited a strong relationship with lipid category. Furthermore, principal component analysis of FSV contents revealed clustering of lipids based both on lipid category and refining history

Oxidative Stability of Commodity Fats and Oils: Modeling Based on Fatty Acid Composition

Although fatty acid (FA) composition is known to be of fundamental importance to oxidative stability in lipids, consistent quantifications of the magnitude of this association have proved elusive. The objective of this study was to quantify the relationship between FA composition and stability on a large scale within comparable lipid systems, with the numerical effects of individual outcome factors (e.g. output of a singular assay, oxidative products after a brief period of time, etc.) attenuated by incorporation into a comprehensive summation of stability. The stability of 50 plant-based oils and fats was modeled according to FA composition, utilizing a quantification of stability that encompassed the complete oxidation curves of four distinct classical assays (two 1° and two 2° oxidation assessments) throughout 2 months of accelerated storage (60 °C). In our models, the concentrations of monounsaturated FA (MUFA), diunsaturated FA (DiUFA), and triunsaturated FA (TriUFA) together demonstrated a very strong correlation with our consolidated measure of stability (r 2 = 0.915; greater than observed with our assessments by individual assays). The resultant model also indicated the relative effect upon magnitude of oxidation of MUFA:DiUFA:TriUFA to be approximately 1:3:12 - substantially greater than the 1:2:3 ratio of their relative unsaturation