Decaffeination of tea extracts by using poly(acrylamide-co-ethylene glycol dimethylacrylate) as adsorbent

Poly(acrylamide-co-ethylene glycol dimethacrylate) was synthesized by thermal polymerization. The adsorption properties of the polymers for catechins and caffeine were studied. Adsorption kinetics showed the polymers preferred to adsorb the catechins rather than caffeine, and adsorption of catechins and caffeine onto the polymers could be described by the pseudo-second-order model. Isothermal equilibrium curves of catechins and caffeine showed a good fit with Langmuir model. The maximum monolayer adsorption capacity (Q_m) of total catechins (192.85–171.11 mg g⁻¹) was 3.9–5.2-folds of caffeine. Adsorption of catechins and caffeine was spontaneous and exothermic process as the change in free energy and enthalpy were negative. Lower temperature was favorable for the adsorption process. Caffeine and catechins were well separated and recovered by eluting polymers-packed column with gradient ethanol, i.e., 30% ethanol elution for separating caffeine, and 80% ethanol elution for recovering catechins. Thus, the synthetic poly(acrylamide-co-ethylene glycol dimethacrylate) could be used as a new adsorbent candidate for producing the decaffeined catechins.     

Complete detoxification of tris(1,3-dichloro-2-propyl) phosphate by mixed two bacteria, Sphingobium sp. strain TCM1 and Arthrobacter sp. strain PY1

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a flame retardant, is regarded as a potentially toxic and persistent environmental contaminant. We previously isolated a TDCPP-degrading bacterium, Sphingobium sp. strain TCM1, which, however, produced a toxic metabolite: 1,3-dichloro-2-propanol (1,3-DCP). This study was undertaken to develop a technique for complete TDCPP detoxification using strain TCM1 with a 1,3-DCP-degrading bacterium, Arthrobacter sp. strain PY1. For efficient detoxification, we designed a resting cell system and examined the effect of freezing and lyophilization treatments for preparation of their resting cells. Results show that treatments had no marked adverse effect on their activities. The TDCPP dephosphorylation by TCM1 resting cells was optimal at 30°C and pH 8.5. Also, 1,3-DCP dehalogenation by strain PY1 resting cells was optimal at 35°C and pH 9.5. Under those respective conditions, the activities were 2.48 μmol h^− 1·OD₆₆₀^− 1 for TDCPP and 0.95 μmol h^− 1·OD₆₆₀^− 1 for 1,3-DCP. Based on these results, we set the reaction temperature to 30°C and pH to 9.0. Then we examined the detoxification of 50 μM TDCPP using mixed resting cells at a final OD₆₆₀ of 0.05 for strain TCM1 and 0.2 for strain PY1. In these conditions, TDCPP was eliminated after 1 h, but some of the resulting 1,3-DCP remained at a constant level. The increase in strain PY1 cells to a final OD₆₆₀ of 4.0 decreased the TDCPP dephosphorylation rate of strain TCM1 cells but achieved complete detoxification of TDCPP during 12 h of reaction.     

Impact of Gram-negative bacteria in interaction with a complex microbial consortium on biogenic amine content and sensory characteristics of an uncooked pressed cheese

The impact of Gram-negative bacteria on sensory characteristics and production of volatile compounds as well as biogenic amines (BA) in the core of an uncooked pressed type model cheese was investigated in the presence of a defined complex microbial consortium. Eleven strains of Gram-negative bacteria, selected on the basis of their biodiversity and in vitro BA-production ability, were individually tested in a model cheese. Four out of 6 strains of Enterobacteriaceae (Citrobacter freundii UCMA 4217, Klebsiella oxytoca 927, Hafnia alvei B16 and Proteus vulgaris UCMA 3780) reached counts close to 6 log CFU g⁻¹ in the model cheese. In core of cheeses inoculated with Gram-negative bacteria, only slight differences were observed for microbial counts (Enterococcus faecalis or Lactobacillus plantarum count differences below 1 log CFU g⁻¹), acetate concentration (differences below 200 mg kg⁻¹) and texture (greater firmness) in comparison to control cheeses. Cheese core colour, odour and volatile compound composition were not modified. Although ornithine, the precursor of putrescine, was present in all cheeses, putrescine was only detected in cheeses inoculated with H. alvei B16 and never exceeded 2.18 mmol kg⁻¹ cheese dry matter. Cadaverine was only detected in cheeses inoculated with H. alvei B16, K. oxytoca 927, Halomonas venusta 4C1A or Morganella morganii 3A2A but at lower concentrations (<1.05 mmol kg⁻¹ cheese dry matter), although lysine was available. Only insignificant amounts of the detrimental BA histamine and tyramine, as well as isopentylamine, tryptamine or phenylethylamine, were produced in the cheese model by any of the Gram-negative strains, including those which produced these BA at high levels in vitro.     

Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment

Hot water treatment was used to decaffeinate fresh tea leaf in the present study. Water temperature, extraction time and ratio of leaf to water had a statistically significant effect on the decaffeination. When fresh tea leaf was decaffeinated with a ratio of tea leaf to water of 1:20 (w/v) at 100 °C for 3 min, caffeine concentration was decreased from 23.7 to 4.0 mg g⁻¹, while total tea catechins decreased from 134.5 to 127.6 mg g⁻¹; 83% of caffeine was removed and 95% of total catechins was retained in the decaffeinated leaf. It is considered that the hot water treatment is a safe and inexpensive method for decaffeinating green tea. However, a large percentage of tea catechins was lost if rolled leaf and dry tea were decaffeinated by the hot water treatment and so the process is not suitable for processing black tea.     

Comparative study of trace elements in certain fish, meat and meat products

Selenium, copper, nickel, zinc, cadmium, manganese, iron, copper and lead contents of certain fish, meat and meat products consumed in Turkey were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). The order of the elements in the meat, meat products and fish samples and their concentration ranges in μg 100 g⁻¹ was Fe (57.7–156.4) > Zn (20–159) > Ni (8.2–24) > Pb (11.5–13.5) > Cr (8.44–9.51) > Cu (7.18–10.01) > Cd (0.77–1.04) > Mn (3.98–10) > Se (1.32–4.6). The elemental concentrations of fish studied seemed to be close to the international standards. The highest trace element concentrations were obtained from past?rma, meat and sausage while the lowest value was observed in Trachurus trachurus (saurel). Iron concentrations in all samples were higher than the recommended values.     

Factors affecting the levels of catechins and caffeine in tea beverage: estimated daily intakes and antioxidant activity

Increased public awareness of health benefits of green tea is generally based on the high polyphenol content of tea leaves and the resulting beverage. A number of factors, such as species, season, agronomic condition and age of the leaves, are known to affect the composition of commercial teas. In the present study the effects of factors associated with domestic preparation and analytical methods, such as brewing time, concentration, solvent and type of tea product, on levels of catechins and caffeine, antioxidant activity and estimated daily intakes were investigated. There were large variations in the levels of total catechins: 43 and 117 mg g^?1 dry matter (DM) (brewed for 30 s and 5 min respectively); 72 and 161 mg g^?1 DM (extracted in boiling water and 50% acetonitrile respectively); 72 and 117 mg g^?1 DM (a tea bag and tea leaves respectively). The effects on caffeine content were comparatively smaller. These variations consequently led to considerable variations in estimated daily intakes based on three cups (600 ml), ranging between 538 and 2014 mg g^?1 DM of total catechins and between 103 and 466 mg g^?1 DM of caffeine. The antioxidant activity was highest (26 680 µmol g^?1 DM) for tea leaves brewed for 5 min and lowest (10 110 µmol g^?1 DM) for a tea bag product brewed for 1 min. Copyright © 2005 Society of Chemical Industry     

Effects of nisin, EDTA and salts of organic acids on Listeria monocytogenes, Salmonella and native microflora on fresh vacuum packaged shrimps stored at 4 °C

Nisin (500 IU ml⁻¹), EDTA (0.02 M), potassium sorbate (PS) (3%, w/v), sodium benzoate (SB) (3%, w/v) or sodium diacetate (SD) (3%, w/v); alone or in combination were used to dip uninoculated shrimps and shrimps inoculated with Listeria monocytogenes or Salmonella (∼4.0–5.0 log CFU g⁻¹). Shrimps were then drip-dried, vacuum packaged and stored at 4 °C for 7 days. Untreated shrimps were used as a control. Numbers of L. monocytogenes, Salmonella and native background microflora were determined on uninoculated and inoculated shrimps on days 0, 3 and 7. Nisin–EDTA–PS and nisin–EDTA–SD significantly reduced (p < 0.05) L. monocytogenes numbers by 1.07–1.27 and 1.32–1.36 log CFU g⁻¹, respectively, on day 0 and 3. However, all treatments failed to significantly reduce (p > 0.05) Salmonella counts on shrimps throughout storage. On day 7, numbers of aerobic bacteria, psychrotrophic bacteria and Pseudomonas on combined nisin–EDTA–salt of organic acids treated shrimps were significantly lower (p < 0.05) by 4.40–4.60, 3.50–4.01, and 3.84–3.99 log CFU g⁻¹ respectively, as compared to the control. Dipping in organic acids solutions followed by vacuum packaging and chilled storage can help reduce L. monocytogenes and native microflora, but not Salmonella, on fresh shrimps.     

The efficacy of nisin can drastically vary when produced in situ in model cheeses

Nisin, a bacteriocin produced by strains of Lactococcus lactis, has a broad inhibitory effect against Gram-positive bacteria. This study investigated the efficacy of nisin Z against Lactobacillus sakei when produced by a nisin-producing strain L. lactis in model cheeses manufactured with ultrafiltrated milk. These cheeses, containing 0, 4 or 10% of gelatin in their dry matter, were inoculated with both strains. Measurement of Lb. sakei loss of viability was an indirect indicator of nisin in situ efficacy. After 24 h, the loss of viability of Lb. sakei was from 0.73 ± 0.14 to 3.30 ± 0.60 log₁₀ cfu g⁻¹ in the cheeses with 0 and 10% of gelatin, respectively, indicating a better in situ efficacy of nisin when gelatin was incorporated. However, the concentration of nisin produced by Lactococcus was similar (3.5 μg g⁻¹) in all model cheeses when measured using an enzyme-linked immune sorbent assay (ELISA). The growth of Lactococcus was slightly improved when gelatin was incorporated, leading to a higher lactate concentration, which is one of the factors explaining the increased nisin efficacy. These results reinforced previous observations that prediction of nisin efficacy in complex food systems remains difficult.     

Tensile properties of cooked meat sausages and their correlation with texture profile analysis (TPA) parameters and physico-chemical characteristics

The possibilities of using breaking strength (BS) and energy to fracture (EF) for monitoring textural properties of some cooked meat sausages (chopped, mortadella and galantines) were studied. Texture profile analysis (TPA), folding test and physico-chemical measurements were also performed. Principal component analysis enabled these meat products to be grouped into three textural profiles which showed significant (p < 0.05) differences mainly for BS, hardness, adhesiveness and cohesiveness. Multivariate analysis indicated that BS, EF and TPA parameters were correlated (p < 0.05) for every individual meat product (chopped, mortadella and galantines) and all products together. On the basis of these results, TPA parameters could be used for constructing regression models to predict BS. The resulting regression model for all cooked meat products was BS = −0.160 + 6.600 ∗ cohesiveness − 1.255 ∗ adhesiveness + 0.048 ∗ hardness − 506.31 ∗ springiness (R² = 0.745, p < 0.00005). Simple linear regression analysis showed significant coefficients of determination between BS (R² = 0.586, p < 0.0001) versus folding test grade (FG) and EF versus FG (R² = 0.564, p < 0.0001).     

The role of meat as a source of n-3 polyunsaturated fatty acids in the human diet

It is considered that consumption of very long chain (VLC, carbon chain length ?20) n − 3 PUFAs in most Western populations is sub-optimal and benefits in relation to chronic disease would be gained from increased consumption. This review examines the current contribution that meat makes to dietary intake of VLC n − 3 PUFA and given its current low contribution, how ruminant meat may be enriched. Enrichment both directly with VLC n − 3 fatty acids and indirectly by increasing intake by the animals of α-linolenic acid (ALNA; C18:3 n − 3) are considered. Since it now appears that dietary ALNA is a very limited source of VLC n − 3 PUFA in humans, the indirect route is controversial but since some forages are rich sources of ALNA this route has many sustainability and environmental attractions. Consideration is also given to the increased concentrations of trans and conjugated fatty acids that will arise from enriching ruminant meat with PUFA.     

Application of essential oils in maize grain: impact on Aspergillus section Flavi growth parameters and aflatoxin accumulation

The antifungal activity of Pimpinella anisum L. (anise), Pëumus boldus Mol (boldus), Hedeoma multiflora Benth (mountain thyme), Syzygium aromaticum L. (clove), and Lippia turbinate var. integrifolia (griseb) (poleo) essential oils (EOs) against Aspergillus section Flavi was evaluated in sterile maize grain under different water activity (a_w) condition (0.982, 0.955, and 0.90). The effect of EOs added to maize grains on growth rate, lag phase, and aflatoxin B₁ (AFB₁) accumulation of Aspergillus section Flavi were evaluated at different water activity conditions. The five EOs analyzed have been shown to influence lag phase and growth rate. Their efficacy depended mainly on the essential oil concentrations and substrate water activity conditions. All EOs showed significant impact on AFB₁ accumulation. This effect was closely dependent on the water activity, concentration, and incubation periods. Important reduction of AFB₁ accumulation was observed in the majority of EO treatments at 11 days of incubation. Boldus, poleo, and mountain thyme EO completely inhibited AFB₁ at 2000 and 3000 μg g⁻¹. Inhibition of AFB₁ accumulation was also observed when aflatoxigenic isolates grew with different concentration of EOs during 35 days.     

Effect of fat score on the quality of various meat products

In the larger Swiss abattoirs the fat score (FS) is determined by default as an indicator of fat quality. The FS refers to the iodine number and is related to the degree of unsaturation of the outer layer of backfat. In a feeding trial with Large White gilts, the FS was determined in 47 carcasses. Meat and fat tissues were prepared for the production of salami (SAL), raw-cured bacon (RCB), pork hamburger (PHB) and Vienna sausage (VIS). In the different meat products, the FS was closely related to the percentage of saturated (SFA: r = −0.49 to −0.79) and polyunsaturated fatty acids (PUFA, r = 0.36 to 0.79) for RCB, SAL and PHB (p ? 0.05), but not for VIS. For RCB, significant correlations with FS were seen for the meat:fat-ratio (r = 0.39), fat firmness (r = −0.31) and one fat oxidation marker (1-octen-3-ol: r = 0.51). The texture (r = −0.60), a_w-value (r = 0.63) and one fat oxidation marker (1-octen-3-ol: r = 0.46) were significantly correlated with FS in SAL. On the whole, only a few variables correlated significantly with FS for SAL and RCB and the corresponding relationships were always linear. No significant correlation between FS and any of the technological and sensorial parameters were found for VIS or PHB.     

Influence of vacuum-aging period on bloom development of the beef gluteus medius from top sirloin butts

The gluteus medius (GM) from USDA Select beef carcasses was used to test the effect of aging period on bloom development. Top sirloin butts (IMPS #184) were randomly allocated to 0, 7, 14, 21, 28, and 35 d vacuum-aging at 2 °C (n = 10/aging period). Each week, aged top sirloin butts were faced before two 2.5-cm-thick, non-adjacent steaks were cut and instrumental color (L^∗, a^∗, and b^∗) of the GM was measured at 10-min intervals for 2 h after cutting. Steaks aged for 7 and 14 d were a more vivid (greater chroma values; P < 0.05), redder (greater a^∗ values; P < 0.05), and more yellow (greater b^∗ values; P < 0.05) color than steaks from the other aging periods. Change in total color (ΔE) was greater (P < 0.05) for steaks from top sirloin butts aged 7, 14, and 21 d than steaks from top butts aged 28 and 35 d, whereas oxymyoglobin percentages for steaks from top butts aged 7 and 14 days were greater (P < 0.05) than those from top sirloin butts aged 28 and 35 d. As much as 90% of the total increase (P < 0.05) in a^∗, b^∗, and chroma values, as well as hue angles and oxymyoglobin percentages, was achieved during the first 60 min after cutting.     

Polyphenolic content and antioxidant activity of Eugenia pollicina leaf extract in vitro and in model emulsion systems

The polyphenolic profile of a leaf extract of the Mauritian endemic plant, Eugenia pollicina, was assessed as a source of natural antioxidants. The amounts of flavan-3-ol derivatives determined by HPLC, were in the order of (−)-epicatechin (EC) > (−)-epigallocatechin gallate (EGCG) > (+)-catechin (C) > (−)-epicatechin gallate (ECG) with the levels of Procyanidin B2 and B1 dimers ranging from 1 to 3 mg g⁻¹ FW. The trolox equivalent antioxidant capacity and ferric reducing antioxidant power values were 796 ??mol g⁻¹ FW and 302 ??mol g⁻¹ FW respectively. E. pollicina extracts also strongly inhibited the FeCl₃ and ascorbate-dependent microsome lipid peroxidation, a function that is linked to their flavonoid contents. The extent of DNA damage induced by the extract under study in the copper-phenanthroline assay was lower than the effect of a reference of 240 ??M ascorbate. E. pollicina extracts also inhibited lipid autoxidation in the 30% (v/v) olive oil and soybean oil oil-in-water (O/W) emulsions and was effective in slowing down the formation of hydroperoxides in the emulsions during 13 days storage at 40 °C as determined by the peroxide, conjugated diene and para-anisidine values. The high levels of total phenolics, flavonoids and procyanidins measured indicate that E. pollicina is a potential source of antioxidants relevant to the maintenance of oxidative stability of the food matrix, cosmetics and/or pharmaceutical preparations.     

A study on chemical estimation of pu‐erh tea quality

Chemical compositions and infusion colour differences of seven pu‐erh tea samples and their correlation to sensory quality were investigated. The results showed that the pu‐erh tea contained 37.1 mg g^?1 caffeine, 15.7 mg g^?1 amino acids, 67.0 mg g^?1 polyphenols and 8.41 mg g^?1 total catechins, on average. Among the 17 tested volatile compounds, n‐valeraldehyde was not detected. The most abundant volatile was β‐ionone and the next was linalool oxide II. Infusion colour analysis showed that the pu‐erh tea had deep hue with ΔE ranging from 66.8 to 79.2. Spearman's linear correlation analysis showed that total quality score (TQS) of the pu‐erh tea was significantly correlated to concentration of amino acids, linalool oxide II and infusion colour indicator ΔE. Five components were extracted from the 34 tested indicators by principal component analysis and were regressed on the TQS to produce six Pearson's linear regression equations for estimating sensory quality of pu‐erh tea, among which two were statistically significant, ie TQS = 57.47 ? 0.18geraniol + 0.33polyphenols ? 1.14n‐caproaldehyde ? 1.38linalool oxide I + 0.21caffeine (p < 0.01) and TQS = 57.42‐0.03Citral + 0.33polyphenols ? 1.14n ? caproaldehyde ? 1.40linalool oxide I + 0.20caffeine (p < 0.01). Copyright © 2004 Society of Chemical Industry