In vitro determination of digestible and unavailable protein in edible seaweeds

Edible seaweeds are considered a complementary source of food protein for human and animal nutrition. The physiological effects of seaweed protein depend on the degree of enzymatic digestion of protein in the small intestine and bacterial fermentation in the large intestine. The objective of this work was to estimate total, digestible, fermentable and unavailable protein in some red and brown seaweeds. Brown seaweeds Fucus vesiculosus, Laminaria digitata and Undaria pinnatifida and red seaweeds Chondrus crispus and Porphyra tenera were treated with pepsin and pancreatin to separate digestible protein. Residues containing indigestible protein were inoculated for 24 h with rat caecal droppings, and protein contents were evaluated in the non‐fermented residue. Protein content in the seaweeds ranged from 8.9 to 25% of dry matter. Digestible protein was the major protein fraction (69%) only in P tenera; in the other seaweeds, this fraction ranged from 15 to 45%. Significant amounts of unavailable protein were found in all samples (2–24%). The distribution of total protein among the three fractions, ie digestible, fermentable and unavailable protein, could yield information about the physiological and metabolic consequences of the intake of seaweed proteins. © 2002 Society of Chemical Industry     

Composition and potential uses of mesquite pods (Prosopis pallida L): Comparison with carob pods (Ceratonia siliqua L)

The composition of mesquite pods (Prosopis pallida L) (PP), a legume cultivated in the large desert areas of Peru, was studied. These fruits have at the present time very little practical or commercial use. Taking into account the morphological and compositional similarities to Mediterranean carob pods (Ceratonia siliqua L) (CS), which are widely used in the food industry, some applications of PP are considered. PP shows better nutritional properties than CS, mainly owing to its lower polyphenolic content and higher protein digestibility.     

A chemical study of the protein fraction of mediterranean sweet almond varieties (Prunus amygdalus)

Summary The protein contents and amino-acid compositions of five Mediterranean almond varieties were determined. The protein contents were between 18 and 24 g/100 g of almond, according to variety. The content of each amino-acid, expressed in g/100 g of protein, was similar in all varieties. The essential amino-acid composition was compared with the FAO pattern of amino-acid requirements and to the protein of milk and eggs. Percentages of albumins, globulins, glutelins and prolamines were also determined.

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Eine chemische Studie der Proteinfraktion mediterraner Süßmandelvarietaten (Prunus amygdalus)

Zusammenfassung Der Proteingehalt and die Aminosäurenzusammensetzung von fünf mediterranen Mandelvarietäten wurden bestimmt. Der Proteingehalt liegt je nach Varietät zwischen 18 and 24 g/100 g Mandeln. Der Gehalt an jeder einzelnen Aminosäure, ausgedrückt in g/100 g Protein, ist in allen Varietäten ähn-lich. Außerdem wurde der Prozentgehalt an Albumin, Globulin, Glutelin and Prolamin bestimmt.

     

Determination of hemicellulose, cellulose and lignin contents of dietary fibre and crude fibre of several seed hulls. Data comparison

Summary The contents of hemicellulose, cellulose and lignin in neutral-detergent fibre, and acid-detergent fibre in hulls of hazelnuts, peanuts, coconuts, sunflower seeds, pumpkin seeds, acorns and chestnuts were determined. Similar cell-wall characteristics for sunflower-acorn, peanut-pumpkin and hazelnut-chestnut pairs can be deduced from their similar composition. High amounts of hemicellulose and lower ones of cellulose and lignin are dissolved in the process of determining crude fibre. The results are discussed.

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Bestimmung des Hemicellulose-, Cellulose- und Lignin-Gehaltes der Rohfaser verschiedener Schalen. Datenvergleich

Zusammenfassung Der Gehalt an Hemicellulose, Cellulose und Lignin von Erdnuß-, Haselnuß-, Sonnenblumensamen-, Kastanie-, Kürbissamen-, Eichel-, und Kokosnußschalen wurde untersucht. Die Zusammensetzung der Paare Sonnenblumensamen und Eichel, Erdnuß und Kürbissamen und Haselnuß und Kastanie sind ähnlich. Daraus kann man folgern, daß sie ähnliche Zellwandzusammensetzungen haben. Große Mengen von Hemicellulose und niedrige von Cellulose und Lignin wurden bei der Bestimmung der Rohfaser aufgelöst.

     

Confidence intervals for the overall effect size in random-effects meta-analysis.

One of the main objectives in meta-analysis is to estimate the overall effect size by calculating a confidence interval (CI). The usual procedure consists of assuming a standard normal distribution and a sampling variance defined as the inverse of the sum of the estimated weights of the effect sizes. But this procedure does not take into account the uncertainty due to the fact that the heterogeneity variance (τ2) and the within-study variances have to be estimated, leading to CIs that are too narrow with the consequence that the actual coverage probability is smaller than the nominal confidence level. In this article, the performances of 3 alternatives to the standard CI procedure are examined under a random-effects model and 8 different τ2 estimators to estimate the weights: the t distribution CI, the weighted variance CI (with an improved variance), and the quantile approximation method (recently proposed). The results of a Monte Carlo simulation showed that the weighted variance CI outperformed the other methods regardless of the τ2 estimator, the value of τ2, the number of studies, and the sample size. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Macromolecular Antioxidants and Dietary Fiber in Edible Seaweeds

Seaweeds are rich in different bioactive compounds with potential uses in drugs, cosmetics and the food industry. The objective of this study was to analyze macromolecular antioxidants or nonextractable polyphenols, in several edible seaweed species collected in Chile (Gracilaria chilensis, Callophyllis concepcionensis, Macrocystis pyrifera, Scytosyphon lomentaria, Ulva sp. and Enteromorpha compressa), including their 1st HPLC characterization. Macromolecular antioxidants are commonly ignored in studies of bioactive compounds. They are associated with insoluble dietary fiber and exhibit significant biological activity, with specific features that are different from those of both dietary fiber and extractable polyphenols. We also evaluated extractable polyphenols and dietary fiber, given their relationship with macromolecular antioxidants. Our results show that macromolecular antioxidants are a major polyphenol fraction (averaging 42% to total polyphenol content), with hydroxycinnamic acids, hydroxybenzoic acids and flavonols being the main constituents. This fraction also showed remarkable antioxidant capacity, as determined by 2 complementary assays. The dietary fiber content was over 50% of dry weight, with some samples exhibiting the target proportionality between soluble and insoluble dietary fiber for adequate nutrition. Overall, our data show that seaweed could be an important source of commonly ignored macromolecular antioxidants.     

Anti-oxidant capacity of dietary polyphenols determined by ABTS assay: a kinetic expression of the results

The 2, 2^′‐Azino‐bis(3‐ethylbenz‐thiazoline‐6‐sulfonic acid) (ABTS)/Trolox equivalent anti oxidant capacity (TEAC) assay, which measures the ability of compounds to scavenge the ABTS radical cation (ABTS^?+) in relation to Trolox (TEAC) is one of the most widely used methods to determine anti oxidant capacity. Usually, the measurements are based on a fixed end‐point (4–6 min), which may not take into account the different kinetic behaviour of anti‐oxidants. The aim of this work was to propose a kinetic procedure for ABTS^?+ assay, by using the kinetic parameters ED₅₀, t_EC50 and AE [antiradical efficiency = 1/(ED₅₀ × t_EC50)], previously applied to the 2, 2‐Diphenyl‐1‐picrylhydrazyl (DPPH^?) assay. It was found that some polyphenols standards – ferulic acid, resveratrol and others‐have not yet completed their reaction at the fixed end‐point. The consideration of kinetic parameters in this method may provide a more thorough understanding of the behaviour of the anti‐oxidants. A comparison of the activity of anti‐oxidants measured by the scavenging of ABTS^?+ with that of DPPH^? was also carried out.     

Antimicrobial Activity of Vanillin and Mixtures with Cinnamon and Clove Essential Oils in Controlling <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> and <Emphasis Type="Italic">Escherichia coli</Emphasis> O157:H7 in Milk

The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of vanillin against Listeria monocytogenes Scott A and Escherichia coli O157:H7 was determined in tripticase soy broth (TSB), pH 7 and 6, incubated at 35 °C/24 h and in semi-skim milk incubated at 35 °C/24 h and 7 °C/14 days. The influence of the fat content of milk on the antimicrobial activity of vanillin was tested in whole and skim milk incubated at 7 °C/14 days. Mixtures of clove and cinnamon with vanillin were also evaluated in semi skim milk incubated at 7 °C. The MICs for L. monocytogenes were 3,000 ppm in TSB (pH 7) and 2,800 ppm in TSB (pH 6). The MICs for E. coli O157:H7 were 2,800 ppm in TSB (pH 7) and 2,400 ppm in TSB (pH 6). The MBCs in TSB were 8,000 ppm for L. monocytogenes and 6,000 ppm for E. coli O157:H7. The pH values assayed did not influence significantly the MIC or MBC in TSB. The MICs in semi-skim milk for L. monocytogenes and E. coli O157:H7 were 4,000 and 3,000 ppm at 35 °C/24 h, and 2,500 and 1,000 ppm at 7 °C/7 days, respectively. The MBCs were 20,000 ppm for L. monocytogenes and 11,000 ppm for E. coli O157:H7. High incubation temperatures did not affect the MBC but increased the MIC of the vanillin in milk. This effect could be attributed to the increased membrane fluidity and to the membrane perturbing activity of vanillin at low temperatures. The fat in milk reduced significantly the antimicrobial activity of vanillin, probably due to effect protective of the fat molecules. Mixtures of clove and cinnamon leaves inhibited the growth of L. monocytogenes in a similar way that vanillin alone but had a synergistic effect on the E. coli O157:H7. Mixtures of cinnamon bark and vanillin had always a synergistic effect and some of the combination assayed showed bactericidal activity on the population of L. monocytogenes and E. coli O 157:H7.     

Optimisation of preservatives for dealcoholised red wine using a survival model for spoilage yeasts

To optimise the application of preservatives in a new commercial dealcoholised red wine (DRW), a survival model of Rhodotorula mucilaginosa and Saccharomyces cerevisiae was developed. A factorial design included three variables, each at three levels: potassium sorbate, sodium metabisulphite and dimethyl dicarbonate (0, 100 and 200 mg L^?1). DRW samples were inoculated with a cocktail of yeasts and counts were performed after 1, 2, 3, 4, 6 and 8 weeks of incubation. Logistic regression analysis was used to create survival models. Potassium sorbate and sodium metabisulphite did not show any fungicide effect alone, while the model predicts that dimethyl dicarbonate at 185 mg L^?1 has fungicide activity. The interaction of potassium sorbate and dimethyl dicarbonate was statistically significant, so both could act as synergic preservatives. The logistic model obtained was validated with a 100% of accuracy for the conditions tested. Combining use of the studied preservatives reduced the individual dose for preservation of DRW.