Levels of biogenic amines as a measure of the quality of the beer fermentation process: Data from Belgian samples

Biogenic amines were determined by HPLC in four beer types. In spontaneously fermented beers (SF beers), the amounts of vasoactive amines reached high levels, namely a mean value (1) above 20 mg/l for tyramine and (2) close to 10 mg/l for histamine. Considering the bacterial origin of these amines, we established a calculation formula for a Beer biogenic amine index (Beer BAI), reflecting the microbiological quality of the fermentation process. Using this formula we determined a mean Beer BAI value lying between 0.84 ± 0.89 (high quality) in low fermented beers and 16.2 ± 13.9 in SF beers. BAI values ⩾10 (poor hygienic fermentation process) corresponded to beers showing values of vasoactive BA (>10 mg/l) that could cause health troubles in certain types of consumers (people under treatment with monoamine-oxidase medication or genetically more sensitive to food-born BA).     

Evaluation of bioactive amine and mineral levels in Turkish coffee

Coffee is one of the most popular drinks across the world and its enormous commercial and social importance is obvious. The levels of nine bioactive amines and five minerals, as well as pH, color, total ash and dry matter characteristics, were determined in different brands of ground and brewed Turkish coffees for the first time. Turkish coffee is a method of preparation, not a kind of coffee. Furthermore, this paper reported the estimated daily mineral intake of five elements. The amines were extracted with trichloroacetic acid (TCA) and quantified by reversed-phase high performance liquid chromatography (HPLC), pre-column derivatization with benzoyl chloride. Of the nine bioactive amines under study putrescine, cadaverine, tyramine and serotonin were detected in all coffee samples. Serotonin was the prevailing bioactive amine in both ground and brewed coffees. The total amine levels in the ground coffee varied from 126.0 mg/kg to 352.2 mg/kg. The total amine levels in the brewed coffee varied from 5.679 mg/L to 48.88 mg/L. The concentrations of five minerals (Mg, Mn, Zn, Na, K) were determined after dry mineralization of both ground and brewed coffee samples. The total mineral contents were analyzed by high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS). Potassium was the prevailing mineral in both ground and brewed coffees. The mean total mineral contents of ground and brewed coffees were 12673.2 mg/kg and 1014.8 mg/L, respectively. Significant differences were obtained between bioactive amines, minerals (except Na), color values (L*, a*, b*), total ash and total dry matter contents of ground and brewed Turkish coffee samples (P < 0.05).     

Physicochemical and melissopalynological characterization of Estonian summer honeys

The samples of 14 honeys, retained from Estonian beekeepers, were analyzed for parameters such as pH, moisture content, free acidity, electrical conductivity, diastase activity, hydroxymethylfurfural (HMF) content and mineral content, including sodium (Na), potassium (K), magnesium (Mg) and calcium (Ca). Fructose, glucose and disaccharide content were also identified and fructose/glucose ratio was calculated. In addition melissopalynological analyses were carried out for characterization of honeys. The mean values of analyzed honeys were: pH 3.8; moisture 17.3%; free acidity 20.4 mmol/kg; electrical conductivity 0.2 mS/cm; diastase activity 23.1 DN and HMF was below 3.8 mg/kg. Within the mineral content, potassium was quantitatively the most important mineral in the range of 125.79 to 1381.53 mg/kg followed by calcium of 20.37-63.65 mg/kg, magnesium 5.53-25.49 mg/kg and sodium 4.77- 19.44 mg/kg. The predominant sugar in honey samples was fructose having the mean value of 35.91 g/100 g followed by glucose 35.00 g/100 g. The disaccharide average content was 6.00 g/100 g. The melissopalynological analyzes showed that the most dominant pollens in honey samples were cruciferous (Cruciferae)-mainly rape (Brassica napus); rosacean (Rosaceae)-mainly raspberry (Rubus idaeus); white clover (Trifolium repens); sweet clover (Melilotus officinalis) and willow (Salix). The results of honey pollen profile analysis and calculated fructose/glucose ratios (0.89-1.17) both indicated to flower honeys. All of the analyzed honeys were found to meet European Legislation (EC Directive 2001/110) for all parameters.     

Polyphenolic and antioxidant content of white and blue corn (Zea mays L.) products

The polyphenolic and antioxidant content of white, Mexican blue, and American blue corns processed into nixtamal (cooked kernels), tortillas, and chips was investigated. A post-nixtamalization acidification treatment was assessed as a means to reduce polyphenolic and antioxidant losses. Similar anthocyanin composition (cyanidin 3-monoglycosides) and concentration (314 mg/kg) was observed for both blue corn genotypes as was their non-anthocyanin polyphenolic composition ((+)-catechin, free and esterified ferulic acid, and p-coumaric acid derivatives). Six derivatives of ferulic acid (88.8–816 mg/kg) along with the free form (2480 mg/kg), p-coumaric acid (6.6 mg/kg), two protocatechuic acid derivatives (4.2 and 14.2 mg/kg), and gallic acid (3.9 mg/kg) were identified in the white genotype. Both blue genotypes contained higher antioxidant capacity (>8.3 μmol Trolox equivalents/g) yet lower polyphenolic levels (3.6–4.4 g/kg) than the white genotype. Comparable anthocyanin losses were observed when the blue genotypes were processed into nixtamals (37%), tortillas (54%), and chips (78%) that correlated to polyphenolic (r = 0.91) and antioxidant capacity (r = 0.94) losses. Acidification was mainly effective in reducing anthocyanin (9–17%), polyphenolic (10%), and antioxidant capacity (6–14%) losses for the blue genotypes. This study compared polyphenolic and antioxidant content among corn genotypes and confirmed that acidification post-nixtamalization could reduce polyphenolic and antioxidant losses.     

Polar lipids,sphingomyelin and long-chain unsaturated fatty acids from the milk fat globule membrane are increased in milks produced by cows fed fresh pasture based diet during spring

Milk lipids are an interesting source of bioactive molecules with functional and nutritional properties. Although the composition of milk lipids is of utmost importance for food processing and human consumption, it is far from being fully known. The objective of this study was to perform a comparative analysis of the chemical composition of lipids from bovine milks produced in French Brittany during spring (fresh pasture based diet) and winter (corn silage based diet). The polar lipid content and relative proportions of the glycerophospholipids and sphingomyelin were determined using HPLC/ELSD. The fatty acid composition of total lipids and polar lipids was determined using GC. The milks collected in spring contained i) a lower amount of total lipids: 39.7 ± 0.8 g/kg vs 41.7 ± 0.5 g/kg in winter, ii) a higher amount of polar lipids: 138 ± 11 vs 112 ± 8 mg/kg milk; 3.5 ± 0.3 vs 2.7 ± 0.4 mg/g fat, which was related to a smaller size of fat globules, and iii) a higher amount of sphingomyelin, 32 mg/kg milk vs 25 mg/kg milk in winter. Interestingly, the polar lipids from the milk fat globule membrane contained a higher concentration of unsaturated fatty acids in spring (C18:1 n − 9, C18:2 n − 6, C18:3 n − 3 and long-chain n − 3 fatty acids). Milk from cows fed a fresh pasture-based diet during spring is an interesting source of dietary long chain polyunsaturated fatty acids for human consumption.     

Analysis of nutrient and antinutrient content of underutilized green leafy vegetables

Analysis of chemical composition of 13 locally available underutilized green leafy vegetables (GLV) was the objective of this study. Moisture, ash and ether extract of the greens were in the range of 73–95 g/100 g, 0.77–3.54 g/100 g and 0.2–0.9 g/100 g, respectively. Four GLV had high iron content (13.15–17.72 mg/100 g) while the rest had lower levels (2.62–9.86 mg/100 g). Calcium content varied largely between the greens ranging from 41 mg/100 g in Polygala erioptera to 506 mg/100 g in Digera arvensis, whereas phosphorous ranged from 16 to 63 mg/100 g. Ascorbic acid was higher in Delonix elata (295 mg/100 g) and Polygala erioptera (85 mg/100 g) and lower in others (3–46 mg/100 g). Thiamine was found to be less than 0.1 mg/100 g in six greens and 0.1–0.33 mg/100 g in others. Total carotene content ranged between 10 and 35 mg/100 g in all with exceptionally high amount in Cocculus hirsutus (67 mg/100 g) and Delonix elata (60 mg/100 g). $\beta$-carotene was 13–25% of total carotene in all greens. Oxalate content was below 100 mg/100 g in five greens and less than 1400 mg/100 g in the remaining GLV. Tannin content ranged between 61 and 205 mg/100 g in all GLV with the exception of Coleus aromaticus (15 mg/100 g) and Delonix elata (1330 mg/100 g).     

The phenolic compounds and the antioxidant potential of infusion of herbs from the Brazilian Amazonian region

The consumption of tea increased significantly in the past few years as a result of its health benefits as potent antioxidants in the diet. However, studies on the antioxidant compounds from Brazilian tea are scarce. Thus, the aim of this work was to evaluate the total phenolic compounds (TPC) and total flavonoids (TF) contents and the antioxidant capacity (DPPH and β-carotene/linoleic acid system) of nine herb infusions from the Amazonian region, namely agirú (Chrysobalanus icaco), açoita-cavalo (Luehea speciosa), capim-santo (Cymbopogon citratus), erva-cidreira (Lippia alba), graviola (Annona muricata L.), jucá (Libidibia ferrea), pata-de-vaca (Bauhinia ungulata), parirí (Fridericia chica) and sacaca comum (Croton spp.). These herbs were chosen based on popular knowledge and consumption. C. ferrea (68.13 mg GAE/g), L. speciosa (47.54 mg GAE/g) and C. icaco (51.30 mg GAE/g) presented the highest TPC contents, while L. speciosa (12.85 mg CE/g) and L. alba (15.42 mg CE/g) showed the highest TF contents. The highest antioxidant capacity, using both assays, was shown by L. ferrea. The three herbs with the highest TPC contents were selected to be analyzed by high performance liquid chromatography (HPLC) coupled to a diode array detector (DAD). A commercial green tea (Camellia sinensis) was also analyzed as a reference. The main compounds tentatively identified were gallic acid (0.45 mg/g), myricetin (0.78 mg/g) and quercetin (0.14 mg/g) in C. icaco; (+)-catechin (1.20 mg/g) and quercetin (0.14 mg/g) in L. speciosa; gallic acid (0.59 mg/g) and quercetin (0.13 mg/g) in C. ferrea; and gallic acid (0.24 mg/g), (−)-epicatechin (2.44 mg/g), (+)-catechin (0.68 mg/g) and quercetin (0.66 mg/g) in green tea. Among the nine studied herbs, the importance of L. ferrea should be pointed out since it presented the highest TPC content and antioxidant capacity and its gallic acid content was much higher than that of green tea.     

Addition of seaweed (Laminaria digitata) extracts containing laminarin and fucoidan to porcine diets: Influence on the quality and shelf-life of fresh pork

A seaweed extract containing laminarin (L) and fucoidan (F) (L/F) was manufactured from brown seaweed (Laminaria digitata) in spray-dried (L/F-SD) and wet (L/F-WS) forms. The effect of supplementation of pig diets with L/F-SD and L/F-WS (L, 500 mg/kg feed; F, 420 mg/kg feed) for 21 days pre-slaughter, on quality indices of fresh M. longissimus dorsi (LD) steaks was examined. Susceptibility of porcine liver, heart, kidney and lung tissue homogenates to iron-induced (1 mM FeSO₄) lipid oxidation was also investigated. Dietary supplementation with L/F did not increase plasma total antioxidant status (TAS). In LD steaks stored in modified atmosphere packs (80% O₂:20% CO₂) (MAP) for up to 15 days at 4 °C, muscle pH, surface colour (CIE ‘L*’ lightness, ‘a*’ redness and ‘b*’ yellowness values) and microbiology (psychrotrophic and mesophilic counts, log CFU/g pork) were unaffected by dietary L/F. In general, levels of lipid oxidation (TBARS, mg MDA (malondialdehyde)/kg pork) followed the order: C > LF-SD > L/F-WS. A statistically significant reduction in lipid oxidation (P < 0.05) was observed in LD steaks from 75% of pigs (n = 6) fed with L/F-WS compared to controls. Iron-induced lipid oxidation increased in liver, heart, kidney and lung tissue homogenates over the 24 h storage period and dietary L/F-WS reduced lipid oxidation to the greatest extent in liver tissue homogenates. Results demonstrate potential for the incorporation of marine-derived bioactive antioxidant components into muscle foods via the animal's diet.     

Phenolic composition,caffeine content and antioxidant capacity of coffee silverskin

Coffea arabica silverskin (CSS), the inner fruit layer surrounding coffee beans, was analyzed for its (poly)phenolic and caffeine content by means of liquid chromatography–tandem mass spectrometry and evaluated for its antioxidant properties by means of the Folin–Ciocalteu and FRAP methods. The most abundant quantified phenolics were caffeoylquinic acids, with the 5- and 3-isomers being the most relevant (199 mg/100 g and 148 mg/100 g, respectively). The three caffeoylquinic acid isomers reached a total concentration of 432 mg/100 g, corresponding to 74% of the total chlorogenic acids detected in CSS. The level of the three feruloylquinic acids detected was 143 mg/100 g, corresponding to 23%, and the two identified coumaroylquinic acids plus the two caffeoylquinic acid lactones were only marginally contributing to the final figure (only 3% of total hydroxycinnamates). No unconjugated phenolic acid was detected. Caffeine content in CSS was equal to 10 mg/g of product, 3.5 times lower than most coffee brews. The total antioxidant capacity (TAC) of CSS was 139 mmol Fe^2 +/kg, a value similar to those of valuable sources of food antioxidants like dark chocolate, herbs and spices. Besides its potential as a food supplement, CSS may represent an innovative functional ingredient exploitable to increase the TAC of a wide range of food products.     

Storage of extra virgin olive oil and its effect on the biological activity and concentration of oleocanthal

The olive oil phenolic, oleocanthal has recently received attention regarding its anti-inflammatory capacity and the thought that it is partially responsible for the beneficial health effects of the Mediterranean diet. Extra virgin olive oil (EVOO) containing oleocanthal is often consumed after storage for a substantial amount of time and for oleocanthal to indeed provide health benefits, it has to be present in a substantial quantity throughout the shelf-life of EVOO. Therefore, the aim of the current study was to investigate if natural light and/or oxygen (O₂) exposure (via atmospheric air) combined with extended storage, as would occur on a common domestic basis, affected the concentration of oleocanthal in EVOO. One EVOO containing 90 mg/kg oleocanthal was stored for 10 months with and without exposure to light and or O₂. Oleocanthal concentrations were quantified using high performance liquid chromatography–mass spectrometry (HPLC–MS) and its biological activity determined with a taste bioassay measuring the intensity of oropharyngeal irritation. A significant difference in oleocanthal concentration was observed amongst the different storage treatments (p = 0.05). Oleocanthal concentration degraded to a maximum of 37% (90 ± 13 mg/kg to 56 ± 9 mg/kg) after 10 months exposure to both light and O₂. Limiting light and O₂ over 10 months resulted in a 15% decrease in oleocanthal (90 ± 13 mg/kg to 76 ± 9 mg/kg). Oleocanthal biological activity mirrored the results of oleocanthal concentration (r = 0.8, p < 0.05). Overall, the findings support the role of oleocanthal as a potential health promoting compound in EVOO as significant concentrations remain in EVOO after exposure to light, oxygen and over time.     

Distribution of Mercury in Three Marine Fish Species

The aim of this study was to compare distribution of the total mercury (THg) content in three marine fish species: European seabass (Dicentrarchus labrax), Gilt-head bream (Sparus aurata) and Res scorpionfish (Scorpaena scrofa). Samples were collected from the Serbian market during 2014 and analysed by applying inductively-coupled plasma mass spectrometry (ICP-MS). The THg content in analysed fish samples was between 0.017 mg/kg and 0.108 mg/kg and significant differences (p < 0.05) in THg content was established only between Gilt-head bream and Res scorpionfish. The estimated weekly intakes of THg through fish consumption were several times lower than the established value.     

Pinto bean hull extract supplementation favorably affects markers of bone metabolism and bone structure in mice

Hulls from dry edible beans are rich in phenolic compounds recognized as possessing antioxidant activity. The aim of this study was to characterize antioxidant properties of bean hull extract (BHE) and to determine whether BHE supplementation (at 400 or 800 mg/kg for 3 months) affects serum biochemical markers and bone structure in 12-month-old male C57BL/6 mice. Mice supplemented with 800 mg BHE/kg had lower serum tartrate-resistant acid phosphatase and parathyroid hormone concentrations than those on control diet or supplemented with 400 mg BHE/kg. BHE supplementation caused slight decrease in oxidized glutathione concentration in blood (P = 0.07). Compared to the control group, BHE supplementation at 800 mg/kg for 3 months improved bone structural indices, bone mineral density and trabecular thickness in the third lumbar vertebra. These results suggest that BHE supplementation may have beneficial effects on bone health in mice by decreasing bone resorption.     

Chemical composition of wild edible mushrooms and antioxidant properties of their water soluble polysaccharidic and ethanolic fractions

Mushrooms have become attractive as functional foods and as a source of physiologically beneficial bioactive compounds. Herein, we describe and compare the chemical constituents (phenolic compounds, macronutrients, sugars, fatty acids, tocopherols and ascorbic acid) of four wild edible mushrooms widely appreciated in gastronomy: Armillaria mellea (Vahl) P. Kumm., Calocybe gambosa (Fr.) Donk, Clitocybe odora (Fr.) P. Kumm., Coprinus comatus (O.F. Müll.) Pers. Furthermore, the antioxidant activity of their water soluble polysaccharidic and ethanolic fractions was studied by three different in vitro assays. C. comatus revealed the highest concentrations of sugars (43.23/100 g dry weight), PUFA (77.46%), phenolic compounds (45.02 mg/kg), tocopherols (301.03 μg/100 g) and, among all of the fractions tested, its ethanolic fraction showed the highest antioxidant activity (EC₅₀ < 2.6 mg/ml). C. odora revealed one of the highest ascorbic acid (172.65 mg/100 g) contents and its water soluble polysaccharidic fraction showed the best antioxidant properties (EC₅₀ < 3.6 mg/ml) among the polysaccharidic fractions. The studied mushrooms species could potentially be used in well-balanced diets and as a source of bioactive compounds.     

Histamine accumulation and histamine-forming bacteria in Indian anchovy (Stolephorus indicus)

Accumulation of histamine, trimethylamine (TMA), and total volatile base nitrogen (TVB-N), as well as microbial population incidence in Indian anchovy (Stolephorus indicus) during storage in ice and at 15 and 35 °C were investigated. Histamine was as low as 1.9 mg/100 g in 15 days at ice storage, but it increased to 19.0 mg/100 g after 32 h at 15 °C. Histamine rapidly increased to 25.4 mg/100 g when stored at 35 °C for 8 h. TVB-N and TMA began to sharply increase after 11 days in ice storage, but abruptly increased after 16 and 8 h of storage at 15 and 35 °C, respectively. A high number of Enterobacteriaceae (10¹⁰–10¹¹ cfu/g) was detected and shown to be the dominant group of microbial flora during spoilage of Indian anchovy at both 15 and 35 °C. A total of 153 bacterial strains were selected from the prescreening step using various selective media. Only 75.8% of these selected isolates showed a positive reaction in Niven's differential medium, and 27.6% of the positive isolates were true histamine formers when confirmed by the enzymatic method. Prolific histamine formers were identified as Morganella morganii, Proteus vulgaris, and Enterobacter aerogenes, and produced high histamine content of 104.1–203.0 mg/100 ml. Optimum growth and histamine production of selected strains of these three species was at 35 °C in histamine evaluation broth (HEB) containing 0.5% NaCl, pH 5. E. aerogenes produced the highest histamine of 500 mg/100 ml at the optimum condition. All studied strains did not produce histamine at ⩾10% NaCl.     

Occurrence of histamine and histamine-forming bacteria in salted mackerel in Taiwan

Thirty-three samples of salted mackerel sold in retail markets and supermarkets in Taiwan were tested to determine the occurrence of histamine and histamine-forming bacteria. The numbers of aerobic plate count (APC) in all samples were below the Taiwanese regulatory level of 6.47 log cfu/g. The levels of pH, salt content, and total coliform in all samples ranged from 5.7 to 6.4, 5.0 to 18.1%, and <3 to 60 most probable number (MPN)/g, respectively. None of these samples contained Escherichia coli. However, eight of the 33 samples (24.2%) had unacceptable levels of total volatile basic nitrogen (TVBN), based on Taiwanese standard for TVBN in seafood products. Although the average content for each of the nine biogenic amines in all samples was less than 3 mg/100 g (30 ppm), two of the 18 samples collected from southern Taiwan contained 70.1 and 120.2 ppm of histamine, which are more than the 50 ppm allowable limit suggested by the US Food and Drug Administration. Of the 40 presumtive histamine-forming bacterial colonies isolated on the differential agar plates for the test samples, 4 strains produced histamine, ranging from 18.3 to 21.0 ppm, in TSBH broth supplemented with 2% L-histidine. These histamine-producing bacteria were identified as Pantoea sp. (2 strains), Pantoea agglomerans (1 strain), and Enterobacter cloacae (1 strain).     

Influence of preprocessing methods and fermentation of adzuki beans on γ-aminobutyric acid (GABA) accumulation by lactic acid bacteria

The effects of pre-processes (immersing, germinating, and cold shock) and fermentation conditions of adzuki beans on γ-aminobutyric acid (GABA) accumulation using mixed cultures of Lactococcus lactis and Lactobacillus rhamnosus were investigated in this study. Among the preprocessing methods, cold shock treatment resulted in the highest observed GABA content (201.2 mg/100 g); a 150-fold increase compared to the non-treated adzuki beans. The LAB strains grew rapidly in cold-treated adzuki bean substrates and reached 10⁸ cfu/ml after 24 h of fermentation at 30 °C. After optimization, the GABA yield reached 68.2 mg/100 ml; a 20-fold increase compared to the non-fermentation yield. The viable cell counts of LAB remained above 10⁸ cfu/ml after 28 days of storage at 4 °C. Our results suggest that the combination of cold shock pretreatment and fermentation by LAB may be used for the preparation of adzuki beans with high GABA content, which can then be used as a natural resource of functional foods.     

High molecular weight persimmon tannin is a potent antioxidant both ex vivo and in vivo

The antioxidant activities of high molecular weight persimmon condensed tannin (HMWPT) were evaluated in an ex vivo tissue system and in vivo. Addition of HMWPT to mouse liver homogenate protected the samples against auto-peroxidation or H₂O₂- or Fe²⁺/ascorbic acid-induced lipid peroxidation. The IC₅₀ values for HMWPT were 4.32 ± 0.20 μg/mL (auto-oxidation), 1.36 ± 0.40 μg/mL (H₂O₂-induced peroxidation) or 0.20 ± 0.09 mg/mL (Fe²⁺/ascorbic acid-induced peroxidation). Mice were oxidatively stressed with bromobenzene to test the antioxidant activity of HMWPT in vivo. An oral dose of HMWPT at 200 or 400 mg/kg HMWPT significantly (P < 0.01) prevented the bromobenzene-induced decrease in serum and liver superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities, and decreased liver malondialdehyde levels in bromobenzene-treated mice (P < 0.01). The results suggest that dietary HMWPT may provide protection from oxidative damage both ex vivo and in vivo.     

Three dimensional temporal and spatial distribution of adult Oryzaephilus surinamensis and Sitophilus oryzae in stored wheat under different temperatures,moisture contents,and adult densities

Three dimensional temporal and spatial distributions of adult Oryzaephilus surinamensis at densities of 0.1, 1.0, and 5.0 adults/kg wheat (referred to as A/kg) and adult Sitophilus oryzae at densities of 1.0, 5.0, and 10.0 A/kg were determined in bins filled with 1.5 t wheat having 11.0 ± 0.8, 13.0 ± 0.6, or 15.0 ± 0.5% moisture content at 20 ± 1, 25 ± 1 or 30 ± 1 °C. At each of the five sampled locations, wheat was separated into three 15 kg vertical layers and the number of adults in each layer was counted.Less than 30% of adult O. surinamensis were recovered in the top layer, while more than 80% of adult S. oryzae were recovered in the top layer. Adults of O. surinamensis preferred the center locations in each layer and adults of S. oryzae preferred the top layer. Densities of both species at adjacent locations in the horizontal direction were autocorrelated with each other. The temporal continuous property might not exist for the adults of O. surinamensis but exists for the adults of S. oryzae. Even though both species had aggregated and clumped distribution at any temperature, moisture content and adult density, adults of O. surinamensis had a more homogeneous distribution than S. oryzae. These characterized patterns of distribution of adult insects could be used to effectively estimate their density inside stored grain-bins.     

Fat contributes to the buffering capacity of chicken skin and meat but enhances the vulnerability of attached Salmonella cells to acetic acid treatment

Chicken skin and chicken meat display different buffering effects which may impact the survival of Salmonella attached to them when treated with acids. This study investigated the role that differences in fat composition of chicken skin and meat play in their buffering capacity. The survival of Salmonella attached to chicken skin and meat in the presence of fat, and treated with acetic acid was also investigated. Fat was extracted from chicken skin and meat and the buffering capacities of chicken skin, meat, extracted fat and their respective remnants were determined. Two strains of Salmonella Typhimurium and two strains of S. Enteritidis were attached independently to each of the chicken component listed above and enumerated before and after treatment with 0.3 M acetic acid. Chicken skin has a higher fat content as compared to chicken meat. Skin (13 mmol H⁺/(pH1 kg)) had a stronger buffering capacity (p < 0.05) than the extracted fat alone and skin remnants alone (7.0 mmol H⁺/(pH 1 kg) and 6.9 mmol H⁺/(pH 1 kg) respectively). From an initial inoculum (~ 9 log CFU/g), Salmonella cells attached better (p < 0.05) to chicken meat (~ 8 log CFU/g) and chicken skin (~ 7 log CFU/g) than extracted fat (~ 1.5 log CFU/g). Skin remnants without fat were better (p < 0.05) at protecting attached Salmonella than other chicken components. For example S. Typhimurium ATCC 33062 decreased ~ 1 log CFU/g (p < 0.05) on skin remnants after acetic acid treatment while its viable counts on other components decreased from ~ 1.5 to 7 log CFU/g (p < 0.05). We suggest that the fat content present in the skin may enhance the vulnerability of attached cells to acetic acid.     

Effect of different dietary levels of natural-source vitamin E in grow-finish pigs on pork quality and shelf life

Improving pork quality and shelf life is important in today’s swine industry because higher levels of DDGS are incorporated into pig diets. Relatively high level of poly-unsaturated fatty acids (PUFA) in DDGS may increase pork susceptibility to lipid oxidation and thus reduce pork shelf life. Antioxidants such as vitamin E may delay the onset of pork lipid oxidation when used as an ingredient in the diet. This experiment examined carcass characteristics, meat quality, shelf life, and color stability in pork from pigs (n = 150) fed five levels of a natural vitamin E (Nova-E) and one level of synthetic vitamin E. Natural vitamin E and synthetic vitamin E had no effect on carcass characteristics or meat quality. Increasing dietary natural vitamin E from 10 to 200 mg/kg decreased lipid oxidation. Lipid oxidation of pork chops and ground pork was similar between pigs fed 40 mg/kg and higher levels of natural vitamin E, indicating no additional benefits from supplementing beyond 40 mg/kg natural vitamin E. Supplementing 200 mg/kg synthetic vitamin E decreased pork lipid oxidation when compared to supplementing 10 mg/kg natural vitamin E. High levels of natural vitamin E or synthetic vitamin E, however, did not prevent discoloration of loin chops. These data indicate that natural vitamin E was effective to help reduce lipid oxidation and the effective minimal level of dietary supplementation appeared to be 40 mg/kg.