Effect of acute consumption of oolong tea on antioxidant parameters in healthy individuals

We evaluated the ability of a ready-to-drink oolong tea (OOL) to modulate plasma antioxidant status in healthy subjects, compared to a placebo drink (PLA) without oolong extract but with ascorbic acid. In vitro, ascorbic acid was the only contributor to ferric reducing antioxidant power (FRAP) and total radical-trapping antioxidant parameter (TRAP) assay of PLA. Ascorbic acid contributed 16.5% and 9.7% of the antioxidant capacity of OOL. In vivo, ingestion of 500 mL of OOL significantly increased plasma TRAP at 30 min and 1 h, compared to 500 mL of PLA, which was ineffective. Plasma FRAP significantly increased at 1, 2 and 4 h for OOL and at 2 h for PLA. Both PLA and OOL significantly increased urinary FRAP over 0–5 h. Urinary FRAP levels went back to baseline at 5 h for PLA tea and remained higher for OOL tea in the interval time 5–12 h (p < 0.01). OOL represents a dietary source of antioxidants able to modulate antioxidant status in humans.     

Studies on insect infestation in chocolates

The ability of stored-product pests including the cigarette beetle, Lasioderma serricorne, the sawtoothed grain beetle, Oryzaephilus surinamensis, the rust-red flour beetle, Tribolium castaneum, and the almond moth, Ephestia cautella, to infest chocolates under packaged and unpackaged conditions was investigated in the laboratory at 25±1 °C and 65±5% r.h. Four types of chocolates were investigated: milk, nut, dried fruit and nut, and wafer chocolates. Adults (beetles only, 20 per replicate) or eggs (30 per replicate) were released on unpackaged and packaged chocolates and infestation levels (number of living adults and larvae) were determined 45 days later. When adult beetles were released on unpackaged chocolates, the degree of infestation varied depending on the species and the type of chocolate. The highest infestation observed in unpackaged chocolate was that of O. surinamensis in wafer chocolate (mean 138.4). When eggs were released on unpackaged chocolates, the most numerous species was E. cautella in dried fruit and nut chocolate (mean population=180.8). With packaged chocolates exposed to adults or eggs, insect infestation was nil or negligible (mean population <6.0). Although infestation levels were low, infestations were found in 50% of treatments over all. Damage to the packaging material along the folds or edges was observed in infested chocolates. The study has shown that milk, nut, dried fruit and nut, and wafer chocolates can support insect infestation and therefore, insect-proof packing of the chocolates and storage under hygienic conditions are important to avoid customers’ complaints.     

Thermal inactivation of Salmonella spp. during conching

Although chocolate is a microbiologically stable product it has been described as a vehicle for Salmonella spp. Because of the low water activity (a_w) and the high fat content of chocolate Salmonella spp. shows an increased heat resistance, even during the thermal process of chocolate making. The aim of this study was to evaluate the thermal inactivation of Salmonella spp. during conching in various masses of chocolate and cocoa butter at different temperatures (50-90 °C). The effect of thermal treatment on Salmonella spp. was determined with the MPN (Most-Probable-Number) method. Results of thermal treatment showed approximate D-values for cocoa butter from D_50°C = 245 min to D_60°C = 306 min, for cocoa liquor from D_50°C = 999 min to D_90°C = 26 min and for dark chocolate of D_50°C = 1574 min. z-values were found to be z = 20 °C in cocoa liquor and z = 14 °C in dark chocolate. This study demonstrates that the conching process alone does not ensure the inactivation of Salmonella spp. in different chocolate masses and that an additional decontamination step at the beginning of the process as well as an HACCP concept is necessary during chocolate production to guarantee the absence of Salmonella spp. in chocolates and related products.     

Wheat bran feruloyl oligosaccharides enhance the antioxidant activity of rat plasma

Wheat bran feruloyl oligosaccharides (FOs) possess in vitro antioxidative potential. The aim of this paper is to investigate the protective effect of FOs against oxidative stress in rat plasma. The levels of oxidative stress markers (oxidised glutathione and malondialdehyde) and the activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) in plasma from rats fed with a standard diet supplemented with 1% FOs were evaluated. The anti-radical capacity of rat plasma after ingestion of 0.5 mg FOs was measured using AAPH as the free radical inducer. Compared to the control group, the antioxidant enzyme activity was higher in plasma from rats fed with FOs, and oxidised glutathione and malondialdehyde levels were lower. Plasmas of rats after ingestion of FOs were more resistant to AAPH-induced hemolysis than was the control group (P < 0.01). These results suggest that FOs enhance the level of antioxidative activity in rat plasma in vivo.     

Unfermented and fermented rooibos teas (Aspalathus linearis) increase plasma total antioxidant capacity in healthy humans

The aim of the study was to assess the effect of drinking rooibos tea (Aspalathus linearis) on total antioxidant capacity (TAC), lipid triacylglycerols, cholesterol and glycaemia plasma levels in humans. In vitro, unfermented rooibos tea displayed a 28% higher value of TRAP than did the fermented beverage. An acute intervention study, cross-over design, was performed, with 15 healthy volunteers who consumed 500 ml of either water, unfermented or fermented rooibos teas. Plasma antioxidant capacity increased significantly with both teas, reaching a peak at 1 h post-consumption (+6.6%, p < 0.05 fermented tea; +2.9%, p < 0.01 unfermented tea). No changes in triacylglycerols, cholesterol or uric acid were observed with any of the treatments. A transitory increase in glycaemia at 30 min was linked to glucose upload. The data show that rooibos teas represent a source of dietary antioxidants in humans.     

Chocolate and cocoa: New sources of trans-resveratrol and trans-piceid

trans-Resveratrol and trans-piceid were found for the first time in dark chocolate (at least 0.4 ppm trans-resveratrol and 1 ppm trans-piceid) and cocoa liquor (at least 0.5 ppm trans-resveratrol and 1.2 ppm trans-piceid). Because these compounds are highly sensitive to light, a specific extraction procedure was required to recover them, involving delipidation with toluene and cyclohexane and ethanol/water (80/20, v/v) solid–liquid extraction at 60 °C before reverse-phase HPLC-MS/MS analysis (atmospheric pressure chemical ionization [APCI] in the positive mode). Thanks to an exceptionally high procyanidin content, chocolate products displayed higher antioxidant activity than much more concentrated commercial stilbene extracts.     

Effect of bleeding treatment and perfusion of yellowtail on lipid oxidation in post-mortem muscle

The present study investigated the effects of bleeding treatment and perfusion of antioxidant compounds on lipid oxidation in ordinary and dark muscles of yellowtail in the early stage of ice storage. The lipid hydroperoxide contents of dark muscles obtained from yellowtails with and without bleeding treatment were higher and increased more rapidly than those of ordinary muscles. There were no significant differences in the rates of change of the lipid hydroperoxide content (up to 48 h), fatty acid composition and metmyoglobin formation between dark muscles with and without bleeding treatment. Physiological saline containing ascorbic acid or 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox^®) was perfused into live yellowtail or added to minced dark muscle. Trolox^® significantly (P < 0.01) delayed the accumulation of lipid hydroperoxide in dark muscle compared to ascorbic acid in perfusion experiment. These results indicate that simply removing a portion of the blood from live yellowtail by bleeding is not sufficient to prevent lipid oxidation in the early stage of ice storage. Contrary to this, addition of antioxidants into fish flesh is effective to delay lipid oxidation in post-mortem muscle.     

Antioxidant potential of meso-zeaxanthin a semi synthetic carotenoid

Semi synthetic carotenoid meso-zeaxanthin was evaluated for its antioxidant potential in vitro and in vivo. Meso-zeaxanthin was found to scavenge superoxide radicals, hydroxyl radicals and inhibited in vitro lipid peroxidation. Concentrations needed for 50% inhibition (IC₅₀) were 27.0, 3.5 and 3.2 μg/ml, respectively. It scavenged 2,2-azobis-3-ethylbenzthiozoline-6-sulphonic acid and 2,2-diphenyl-1-picryl hydrazyl radicals and IC₅₀ were 46.5, 6.25 μg/ml, respectively. It also scavenged nitric oxide radicals and IC₅₀ was found to be 2.2 μg/ml. Oral administration of meso-zeaxanthin inhibited superoxide radicals generated in macrophages by 25.2%, 50.1% and 67.2% at doses of 50, 100 and 250 mg/kg b.wt., respectively. One month oral administration of meso-zeaxanthin to mice significantly increased catalase, superoxide dismutase, glutathione and glutathione reductase levels in blood and liver. Levels of glutathione peroxidase and glutathione-S-transferase were also found to be increased in the liver, in a dose dependent manner. These results showed that meso-zeaxanthin has significant antioxidant activity in vitro and in vivo.     

Inhibition effect of procyanidins from lotus seedpod on mouse B16 melanoma invivo and in vitro

Significant growth inhibition effects of procyanidins from lotus (Nelumbo nucifera Gaertn.) seedpod (LSPCs) on mouse melanoma B16 were found both in vivo and in vitro. In vivo treatment with LSPCs inhibited tumour growth in C₅₇BL/6 J mice by 55.3% in terms of average tumour weight. LSPCs can significantly (P < 0.05) decrease lipid peroxidation (LPO) levels and increase the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in liver tissue. In vitro assay of anti-cancer activities suggested that LSPCs (25–100 μg/ml) possessed cytotoxicities against mouse melanoma B16 in a dose-dependent mode. Furthermore, LSPCs had significant (P < 0.05) stimulatory effects on mouse splenocyte proliferation. The prevention of tumour growth was exerted through diverse mechanisms, including cell-cycle arrest, induction of tumour cell death by apoptosis and increase of Ca²⁺ ions, together with stimulation of antioxidant enzyme activities and immunomodulatory activities.     

Effects of mechanical handling,storage on ice and ascorbic acid treatment on lipid oxidation in cultured Newfoundland blue mussel (Mytilus edulis)

Lipid oxidation of cultured blue mussels (Mytilus edulis) during mechanical handling and storage on ice was investigated. Furthermore, the exposure of blue mussels to ascorbic acid (Asc) as an antioxidant and its effects on lipid oxidation of sample was monitored. Thiobarbituric acid reactive substances (TBARS) of stored mussels were significantly (p < 0.05) higher than those of the fresh mussels. Mechanical handling of mussels, which includes washing, sorting and packaging, for up to 1 h did not affect their oxidative status significantly (p < 0.05). Furthermore, exposing live mussels to specific concentrations of Asc retarded lipid oxidation significantly (p < 0.05) during storage on ice for only 5 days, after which the Asc became a pro-oxidant.     

Strawberry consumption improves plasma antioxidant status and erythrocyte resistance to oxidative haemolysis in humans

Significant increases in the plasma total antioxidant capacity (TAC) have already been reported after acute intake of strawberries. In addition, antihaemolitic effects of strawberry extracts have been recently demonstrated in vitro, revealing that part of the antioxidant properties of strawberry bioactive compounds could lie in their localisation within cell membranes. However, there is a lack of research evidence from in vivo protracted strawberry consumption studies. We carried out a 16-day pilot study where 12 healthy subjects ingested 500 g of antioxidants-rich strawberries daily, and we evaluated the potential effects of fruit consumption on biomarkers of plasma and cellular antioxidant status. A significant increase in fasting plasma TAC and in serum vitamin C concentrations were progressively observed during the period of strawberry supplementation. An enhanced resistance to haemolysis was also observed in both AAPH-treated and untreated erythrocytes, collected during and after the period of strawberry consumption. The results obtained in this work suggest that regular consumption of antioxidant-rich strawberries may exert an improvement on the plasma antioxidant status and an increase on the antihaemolitic defenses of human erythrocytes.     

Oxidative status, in vitro iron-induced lipid oxidation and superoxide dismutase,catalase and glutathione peroxidase activities in rhea meat

Rhea (Rhea americana) muscles Obturatorius medialis (OM) Iliotibialis lateralis (IL) and Iliofibularis (I), obtained from farmed animals, were evaluated regarding their oxidative/antioxidant status. The mean level of thiobarbituric acid reactive substances (TBARS) expressed as malonaldehyde (MDA) content was of 0.84 mg MDA/kg wet tissue for the three muscles. TBARS level was significantly higher in IL than OM and I, with the two latter showing similar levels. The mean level of carbonyl proteins expressed as dinitrophenylhydrazine (DNPH) was 1.59 nmol DNPH mg⁻¹. Carbonyl protein levels were significantly different (P < 0.05) between the three muscles (IL > OM > I). Iron-induced TBARS generation was not significantly different between the three muscles at any time, nor for each muscle during the 5 h of the experiment. Superoxide dismutase activity in IL muscle was significantly higher (P < 0.05) than in I muscle. However, the difference between IL and OM muscles was not significant. The differences between the three muscles became not significant when the results were expressed by mg of protein contained in the extract, instead by g of wet tissue. No differences were found for catalase (μmol of discomposed H₂O₂ min⁻¹ g⁻¹ wet tissue or by mg of protein contained in the extract) and glutathione peroxidase (μmol of oxidized NADPH min⁻¹ g⁻¹ of wet tissue or by mg of protein contained in the extract) activities between the three muscles.     

Properties of sucrose-free chocolates enriched with viable lactic acid bacteria

Chocolate formulated with isomalt and enriched with lactic acid bacteria Streptococcus thermophilus MK-10 and Lactobacillus delbrueckii subsp. bulgaricus 151, added in the form of powdered yoghurt, prepared by spray-drying is a sucrose-free, low-calorie product with functional properties. The technique of the production of chocolate sweetened with isomalt and containing live cells of the aforementioned bacterial strains has been established. Physicochemical and sensory properties of this product as well as survival of cells during 6-months storage at 4 and 18 °C have been determined. The isomalt-containing yoghurt chocolates displayed satisfactory sensory attributes. Their calorific value and consistency (hardness) were similar to those of control sucrose-free chocolates. The total acidity of yoghurt and standard milk chocolates was also similar, whereas yoghurt-containing dark chocolates displayed higher acidity. The characteristics of yoghurt-containing chocolates were a relatively low solid substance content (96.82–96.91% w/w), low Casson viscosity and yield value for milk chocolate masses, and enhanced rheological parameters for dark chocolate masses compared with control sucrose-free chocolates. Because the total number of lactic acid bacteria after 6-months storage at 4 and 18 °C was high (approximately 10⁷ cfu/g), the sucrose-free yoghurt-containing chocolates can be regarded as functional foods.     

Antioxidant properties of various solvent extracts of mulberry (Morus indica L.) leaves

The antioxidant properties and total phenolic contents of methanol, acetone and water extracts of mulberry (Morus indica L.) leaves were examined. Various experimental models including iron (III) reducing capacity, total antioxidant capacity, DPPH radical scavenging activity and in vitro inhibition of ferrous sulphate-induced oxidation of lipid system were used for characterization of antioxidant activity of extracts. The three extracts showed varying degrees of efficacy in each assay in a dose-dependent manner. Methanolic extract with the highest amount of total phenolics, was the most potent antioxidant in all the assays used. In addition, the effect of temperature (50 °C and 100 °C), pH (3, 5, 7, 9 and 11) and storage (5 °C) on the antioxidant activity of methanolic extract was investigated. The antioxidant activity of the extract remained unchanged at 50 °C and was maximum at neutral pH. The extract stored at 5 °C in the dark was stable for 30 days after which the antioxidant activity decreased (p ? 0.05) gradually. On the basis of the results obtained, mulberry leaves were found to serve as a potential source of natural antioxidants due to their marked antioxidant activity.     

Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography–mass spectrometry (HS/GC–MS) revealed pronounced differences in the composition of volatiles in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory profiling described the heap and tray fermented chocolates as sweet with cocoa and caramel flavours, whilst the inoculated chocolates were characterized as fruity, acid and bitter with berry, yoghurt and balsamic flavours. The choice of fermentation technique had the greatest overall impact on the volatile aroma and sensory profile, but whilst the application of starter cultures did affect the volatile aroma profile, differences were too small to significantly change consumer perception of the chocolates as compared to a spontaneously fermented control.     

Effects of taurine on hepatic lipid metabolism and anti-inflammation in chronic alcohol-fed rats

The effects of taurine (Tau) in regulation of lipid metabolism and decreasing inflammation in chronic alcohol-fed rats was investigated. Rats were randomly divided into three groups: (1) isocaloric solution; (2) 3 g alcohol/kg BW/day; (3) 3 g alcohol/kg BW/day + 1 g Tau/kg BW/day for 6 weeks. Liver size and serum/liver lipids of alcohol-fed rats were decreased (p < 0.05) by Tau supplementation, but daily fecal lipid/bile acid outputs were increased (p < 0.05). Regarding de novo lipogenesis, Tau downregulated (p < 0.05) fatty-acid biosynthesis and upregulated (p < 0.05) cholesterol metabolism (CYP7A1) and energy expenditure (PPAR-α). Serum AST and ALT, and hepatic TNF-α levels and MMP-9 activity of alcohol-fed rats were decreased (p < 0.05) by Tau supplementation which may be related to the maintenance of higher (p < 0.05) antioxidant levels (lower thiobarbituric-acid-reactive-substances values and higher trolox equivalent antioxidant capacity) in serum and livers. Our study indicates that Tau downregulates lipogenesis, oxidative stress, and inflammation in chronic alcohol-fed rats.     

Cultivar differences of total anthocyanins and anthocyanidins in red and purple-fleshed potatoes and their relation to antioxidant activity

Total anthocyanins (TAC) and individual anthocyanidins (AN) after hydrolysis were measured in 15 red and purple-fleshed potato cultivars produced in five different locations in the Czech Republic and a new cultivar Blaue St. Galler from Switzerland. It was found that TAC, expressed as cyanidin content, varied between 0.7 mg 100 g⁻¹ FW (cv. Blue Congo) and 74.3 mg 100 g⁻¹ FW (cv. Blaue Ludiano). Major differences in cultivars were found for AN relative abundance. For cv. Highland Burgundy Red a high proportion of pelargonidin (98.7%) was characteristic, whereas cv. British Columbia Blue contained almost exclusively cyanidin. Cultivars Violette and Vitelotte showed a relatively high content of malvidin. Cultivar Shetland Black differed from others with its higher content of peonidin (on average 36.7%). High petunidin abundance in the cultivars Valfi, Blue Congo, Salad Blue, Blaue St. Galler, Blaue Hindel Bank, Blaue Ludiano, Blaue Schweden, Farbe Kartoffel and Salad Red was found. TAC and AN contents highly corresponded with antioxidant activity (AA) determined with the ABTS, FRAP and DPPH assays in vitro. High AA was shown by the cultivars Vitelotte, Violette, Blaue Ludiano, Hafija, and Highland Burgundy Red. Increased height above sea level, higher annual sum of precipitation, and lower annual average temperatures caused higher AA and TAC. A high degree of hydroxylation and/or methoxylation of individual anthocyanidins could contribute in conjunction with other phenolics to high AA (peonidin, delphinidin and malvidin in the cultivars Blue Congo, Highland Burgundy Red and Shetland Black). Consequently, new red and purple-fleshed cultivars with high TAC and highly methoxylated and/or hydroxylated AN could be a promising source of favourable antioxidants in human nutrition.     

Modelling tempering behaviour of dark chocolates from varying particle size distribution and fat content using response surface methodology

Central Composite Rotatable Design (CCRD) for K = 2 was used to study the combined effects of multi-stage heat exchangers for Stages 1 (14–30 °C) and 2 (12–28 °C) coolant temperatures at constant Stage 3 coolant and holding temperatures during tempering of dark chocolates using laboratory-scale mini-temperer. Quantitative data on chocolate temper index (slope) were obtained for products with varying particle size distribution (PSD) (D₉₀ of 18, 25, 35 and 50 μm) and fat (30% and 35%) content. Regression models generated using stepwise regression analyses were used to plot response surface curves, to study the tempering behaviour of products. The results showed that both Stage 1 and Stage 2 coolant temperatures had significant linear and quadratic effects on the crystallization behaviour causing wide variations in chocolate temper index during tempering of products with variable PSD and fat content. Differences in fat content exerted the greatest variability in temperature settings of the different zones for attaining well-tempered products. At 35% fat content, changes in PSD caused only slight and insignificant effect on tempering behaviour. No unique set of conditions was found to achieve good temper in dark chocolate with a specified tempering unit. Thus, different combinations of temperatures could be employed between the multi-stage heat exchangers to induce nucleation and growth of stable fat crystal polymorphs during tempering. Variations in tempering outcomes of the dark chocolates were dependent more on the fat content than PSD.

Industrial relevance

Tempering consists of shearing chocolate mass at controlled temperatures to promote cocoa butter crystallization in a stable polymorphic form. During industrial processing, multi-stage heat exchangers are used to control temperature adjustments to promote formation of appropriate stable polymorphic crystals to obtain products with good snap, colour, contraction, gloss and shelf life characteristics. The process employs varying time–temperature throughputs of the multi-stage units making it difficult to obtain standard tempering conditions for products with variable particle sizes and fat content, thus prolonging equipment standardization periods with consequential effects on processing times and product quality characteristics. Modelling the tempering behaviour of dark chocolates from varying PSD and fat content would enhance our knowledge and understanding on the optimal temperature conditions for obtaining good tempered products during industrial manufacture, with significance for reducing processing (tempering) times and assurances in quality and shelf characteristics.