Arbutin in marjoram and oregano

Arbutin is a hydroquinone derivative that has been found in species of several plant families. Within the genus Origanum the formation of arbutin is polymorphic, with arbutin present in considerable amounts (O. dubium 20.8 ± 15.3 mg/g; wild O. majorana 51.3 ± 15.4 mg/g, cultivated O. majorana 40.6 ± 11.2 mg/g), minor amounts (O. microphyllum 0.1 ± 0.1 mg/g, wild O. onites 0.3 ± 0.1 mg/g, cultivated O. onites 0.1 ± 0.1 mg/g, O. saccatum 0.1 ± 0.1 mg/g, O. solymicum 0.4 ± 1.0 mg/g) or completely absent (O. husnucan-baseri, O. syriacum, O. vulgare). Whereas the most important commercial oregano species (O. onites and O. vulgare) contain no or only minor amounts of arbutin, marjoram (O. majorana) has considerably high amounts. The high variability of arbutin in O. majorana would allow a selection into cultivars with high arbutin content and low arbutin varieties. In a segregating F₂-generation of a species crossing between O. majorana (high content of arbutin) and O. vulgare ssp. vulgare (free of arbutin), the presence of arbutin followed a Mendelian segregation of 3:1, indicating that only one gene is responsible for the polymorphism of arbutin in the genus Origanum. The absence of arbutin in O. vulgare ssp. vulgare or O. syriacum would even enable the breeding of marjoram with no arbutin at all.     

The extreme xerophilic mould Xeromyces bisporus--growth and competition at various water activities

Little is known about the mould, Xeromyces bisporus, unique in its strong xerophilicity and ability to grow at water activity (a_w) 0.62, lower than for any other known organism. The linear growth rates of one fast and one slow-growing strain of X. bisporus were assessed at 20, 25, 30 and 37 °C on solid agar media containing a mixture of glucose and fructose to reduce a_w to 0.94, 0.88, 0.84, 0.80, 0.76 and 0.66. Growth rates of xerophilic species closely related to X. bisporus, viz. Chrysosporium inops, C. xerophilum and Monascus eremophilus, were also assessed. Optimal conditions for growth of both X. bisporus strains were approx. 0.84 a_w and 30 °C, despite FRR 2347 growing two- to five-fold faster than CBS 185.75. X. bisporus FRR 2347 even grew well at 0.66 a_w (0.48 mm/day). C. inops and C. xerophilum were more tolerant of high a_w than X. bisporus, and could be differentiated from each other based on: the faster growth of C. xerophilum; its preference for temperatures ≥ 30 °C and a_w ≥ 0.94 (c.f. ≤ 25 °C and ~ 0.88 a_w for C. inops); and its ability to grow at 0.66 a_w, which is the lowest a_w reported to date for this species. M. eremophilus grew slowly (max. 0.4 mm/day) even in its optimal conditions of ~ 0.88 a_w and 25 °C. To investigate the competitive characteristics of X. bisporus at low a_w, both X. bisporus strains were grown in dual-culture with xerotolerant species Aspergillus flavus and Penicillium roqueforti, and xerophilic species A. penicillioides, C. inops, C. xerophilum and Eurotium chevalieri, on glucose-fructose agar plates at 0.94, 0.84, 0.80 and 0.76 a_w and at 25 °C. Growth rates and types of interactions were assessed. Excretion of inhibitory substances acting over a long-range was not observed by any species; inhibitors acting over a short-range that temporarily slowed competitors' growth or produced a protective zone around the colony were occasionally observed for A. penicillioides, C. inops and C. xerophilum. Instead, rapid growth relative to the competitor was the most common means of dominance. The xerotolerant species, A. flavus and P. roqueforti were dominant over X. bisporus at 0.94 a_w. E. chevalieri was often dominant due to its rapid growth over the entire a_w range. At a_w < 0.80, X. bisporus was competitive because it grew faster than the other species examined. This supports the concept that its ideal environmental niche is sugary foods with low a_w.     

Effect of clay content, homogenization RPM, pH, and ultrasonication on mechanical and barrier properties of fish gelatin/montmorillonite nanocomposite films

The effect of clay content, homogenization RPM, and pH on the mechanical and barrier properties of fish gelatin/nanoclay composite films was investigated. The addition of 5% nanoclay (w/w) increased the tensile strength from 30.31 ± 2.37 MPa to 40.71 ± 3.30 MPa. The 9 g clay/100 g gelatin film exhibited the largest improvements in oxygen and water barrier properties. Oxygen permeability decreased from 402.8 × 10⁻⁶ ± 0.7 × 10⁻⁶ g m/m² day atm to 114.4 × 10⁻⁶ ± 16.2 × 10⁻⁶ g m/m² day atm and the water vapor permeability decreased from 31.2 × 10⁻³ ± 1.6 × 10⁻³ ng m/m² s Pa to 8.1 × 10⁻³ ± 0.1 × 10⁻³ ng m/m² s Pa. The XRD and TEM observation suggested that the ultrasonication treatment (30 min at 40% output) resulted in exfoliation of the silicates.     

Nutritive value of masau (Ziziphus mauritiana) fruits from Zambezi Valley in Zimbabwe

Ziziphus mauritiana (masau) fruits are consumed by many people in Zimbabwe. The fruits contribute significantly to people’s diet when they are in season. The objective of this study was to determine the nutritional content of the fruits and, hence, quantify their contribution to the diet. Samples of masau were collected in two seasons (August 2006 and August 2007). Both macronutrients and micronutrients were determined using standard AOAC methods of analysis. Dry matter content ranged from 21.1 ± 0.2 to 24.1 ± 0.3 g 100 g⁻¹ of edible portion of the sweet and sour fruits, and 84.8 ± 0.2 to 87.2 ± 0.2 g 100 g⁻¹ for the dried fruit. Crude protein per 100 g edible portion of dry weight ranged between 7.9 ± 0.0 and 8.7 ± 0.0 g, crude fat from 0.8 ± 0.0 to 1.5 ± 0.0 g, crude fibre from 4.9 ± 0.0 to 7.3 ± 0.0 g, ash between 3.0 ± 0.0 and 4.3 ± 0.0 g and carbohydrate between 79.5 ± 0.0 and 83.2 ± 0.0 g. The fruits were rich in vitamin C (15.0 ± 0.0–43.8 ± 0.02 mg 100 g⁻¹) and the energy values ranged between 1516.0 ± 1.73 and 1575.0 ± 2.3 kJ 100 g⁻¹. Furthermore, the fruits contained (mg 100 g⁻¹ of dry weight) potassium from 1865.0 ± 1.3 to 2441.0 ± 1.1, calcium from 160.0 ± 0.3 to 254.0 ± 0.1, sodium between 185.0 ± 0.1 and 223.0 ± 0.2, magnesium between 83.0 ± 0.0 and 150.0 ± 0.13 and phosphorous from 87.0 ± 0.1 to 148.0 ± 0.5. Manganese and copper contents ranged between 0.7 ± 0.03 and 1.6 ± 0.03, while iron and zinc ranged between 2.1 ± 0.43 and 4.3 ± 0.1, and 0.6 ± 0.0–0.9 ± 0.0 mg 100 g⁻¹ of dry weight, respectively. The masau fruit is therefore a good potential source of carbohydrates, proteins and micronutrients, such as calcium, potassium, sodium, phosphorous, copper, iron, Vitamin C and zinc.     

Schimmelpilze in Lebensmitteln der Tschechoslowakei

Zusammenfassung Es wurde die Mykoflora von 13 527 g sensorisch unveränderten Lebensmitteln (Pulver) und von 22017 verschiedetien Proben sensorisch unveränderter, an der Oberfläche sterilisierter Körner und Nüsse untersucht.Aus den Proben wurden 147 027 Kolonien von 44 Schimmelpilzgattungen isoliert und identifiziert.Am häufigsten waren Kolonien vonPenicillium sp.,Aspergillus sp. undCladosporium sp. vertreten, weniger oft oder ganz seltenRhizopus sp.,Mucor sp.,Absidia sp.,Alternaria sp.,Circinella sp.,Trichoderma sp.,Botrytis sp.,Paecilomyces sp.,Geotrichum sp.,Syncephalastrum sp.,Scopulariopsis sp.,Phoma sp.,Aureobasidium sp.,Fusarium sp.,Thamnidium sp.,Cunninghamella sp.,Stemphylium sp.,Torula sp.,Trichothecium sp.,Verticillium sp.,Cephalosporium sp.,Mortierella sp.,Neurospora sp.,Ostracoderma sp.,Arthrinium sp.,Monodyctis sp.,Papularia sp.,Acremonium sp.,Chaetomium sp.,Chrysosporium sp.,Beauveria sp.,Cephaliophora sp.,Dactylosporium sp.,Drechslera sp.,Gliomastix sp.,Helminthosporium sp.,Humicola sp.,Monilia sp.,Sepedonium sp.,Ulocladium sp. andWallemia sp.

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Molds in foods of the Czechoslovak Socialistic Republik

Summary The mycoflora of 13.527 g of food powders which were normal upon sensory evaluation as well of 22.017 pieces of surface sterilized grains and nuts was examined in the Czechoslovak Socialist Republic. 147.027 colonies of 44 genera of molds were isolated and identified from samples.Colonies ofPenicillium sp.,Aspergillus sp., andCladosporium sp. occured most often, less often or quite infrequentlyRhizopus sp.,Mucor sp.,Absidia sp.,Alternaria sp.,Circinella sp.,Trichoderma sp.,Botrytis sp.,Paecilomyces sp.,Geotrichum sp.,Syncephalastrum sp.,Scopulariopsis sp.,Phoma sp.,Aureobasidium sp.,Fusarium sp.,Thamnidium sp.,Cunninghamella sp.,Stemphylium sp.,Torula sp.,Trichothecium sp.,Verticillium sp.,Cephalosporium sp.,Mortierella sp.,Neurospora sp.,Ostracoderma sp.,Arthrinium sp.,Monodyctis sp.,Papularia sp.,Acremonium sp.,Chaetomium sp.,Chrysosporium sp.,Beauveria sp.,Cephaliophora sp.,Dactylosporium sp.,Drechslera sp.,Gliomastix sp.,Helminthosporium sp.,Humicola sp.,Moniliasp.,Sepedonium sp.,Ulocladium sp., andWallemia sp.

     

Angiotensin-I converting enzyme inhibitory and antioxidant activities of protein hydrolysates from Phaseolus lunatus and Phaseolus vulgaris seeds

Phaseolus lunatus and Phaseolus vulgaris protein concentrates were hydrolyzed with the enzymes Alcalase^® and Flavourzyme^® at different reaction times, and the angiotensin-I converting enzyme (ACE-I) inhibitory activity, antioxidant properties and amino acid composition measured in the hydrolysates. With Alcalase^®, the highest degree of hydrolysis (DH) in P. lunatus was 37.94% at 45 min, and in P. vulgaris was 49.48% at 30 min. With Flavourzyme^®, the highest DH's were 22.03% and 26.05%, respectively, both at 90 min. ACE-I inhibitory activity in the Alcalase^® hydrolysates was IC₅₀ = 0.056 mg mL⁻¹ for P. lunatus at 90 min, and IC₅₀ = 0.061 mg mL⁻¹ for P. vulgaris at 60 min. In the Flavourzyme^® hydrolysates this activity was IC₅₀ = 0.0069 mg mL⁻¹ for P. lunatus at 90 min and IC₅₀ = 0.127 mg mL⁻¹ for P. vulgaris at 45 min. In SDS-PAGE, the hydrolysates exhibited low molecular weight bands. Antioxidant activity was 11.55 mmol L⁻¹ TEAC mg⁻¹ protein for P. lunatus with Flavourzyme^® at 90 min and 10.09 mmol L⁻¹ TEAC mg⁻¹ protein for P. vulgaris with Alcalase^® at 60 min. Amino acid composition exhibited high amino acid hydrophobic residues content.     

The flavonoid,carotenoid and pectin content in peels of citrus cultivated in Taiwan

The flavonoid, carotenoid and pectin composition in peels of eight varieties of citrus {Ponkan (Citrus reticulata Blanco), Tonkan (C. tankan Hayata), Murcott (C. reticulate × C. sinensis), Wendun (C. grandis Osbeck), Peiyou (C. grandis Osbeck CV), Kumquat (C. microcarpa), Liucheng [C. sinensis (L.) Osbeck], and Lemon [C. limon (L.) Bur]} cultivated in Taiwan was determined. The total flavonoid content exceeded the total carotenoid content. Ponkan (C. reticulata Blanco) peel had the highest total carotenoid content (2.04 ± 0.036 mg/g db) and Wendun (C. grandis Osbeck) and Peiyou (C. grandis Osbeck CV) peels, the lowest (0.036 ± 0.0006 and 0.021 ± 0.0004 mg/g db, respectively). Naringin was abundant in Peiyou (C. grandis Osbeck CV) and Wendun (C. grandis Osbeck) peels (29.8 ± 0.20 and 23.9 ± 0.32 mg/g db, respectively) and hesperidin was aboundant in Ponkan (C. reticulata Blanco), Tonkan (C. tankan Hayata), and Liucheng [C. sinensis (L.) Osbeck] peels (29.5 ± 0.32, 23.4 ± 0.25, 20.7 ± 0.38 mg/g db, respectively). Kumquat (C. microcarpa) peel contained the most diosmin (1.12 ± 0.03 mg/g db) and quercetin (0.78 ± 0.003 mg/g db). Levels of caffeic acid (3.06 ± 0.03–80.8 ± 3.72 μg/g db) were much lower than that of chlorgenic acid, ferulic acid, sinapic acid and ρ-coumaric acid. Ponkan (C. reticulata Blanco), Kumquat (C. microcarpa) and Liucheng [C. sinensis (L.) Osbeck] peels contained the most total amounts of lutein, zeaxanthin, β-cryptoxanthin, and β-carotene (114, 113, and 108 mg/g db, respectively). The total pectin content ranged from 36.0 ± 1.46 to 86.4 ± 3.36 mg/g db.     

Microbiological Attributes of Turkish Butters Sold Under Market Conditions

In this study, microbiological quality of 45 butter samples sold under market conditions at Manisa (Turkey) was investigated. Total coliform, total fecal coliform, Escherichia coli and yeast and mould counts were found between < 1.0 – > 3.15 log₁₀ cfu.g^-1, < 1.0 – > 3.15 log₁₀ cfu.g^-1, < 1.0 – > 3.15 log₁₀ cfu.g^-1 and < 1.0 – > 6.62 log₁₀ cfu.g^-1 respectively. Only in one sample Salmonella was detected. Staphylococcus aureus was not detected in any of the samples. To that extent butters sold under market conditions in Manisa have high coliform, yeast and mould contamination.     

Kinetic studies on strawberry anthocyanin hydrolysis by a thermostable anthocyanin-β-glycosidase from Aspergillus niger

Several kinetic characteristics of a thermostable anthocyanin-β-glycosidase from Aspergillus niger have been evaluated. With strawberry anthocyanins as substrate, at pH optimum (4·0) and t = 30°C, K_m was found to be $\text{123 ± 4 μ}\text{m}$ and V_max, 1·16 ± 0·06 μmol min^?1mg^?1 protein. Temperature optimum was observed at about 68°C. The apparent energy of activation was calculated to be 11 ± 1 kcal/mol. The inhibitory effect of different sugars and sugar derivatives was examined. Glucono-deltalactone ($\text{K}{}_{\mathrm{<mtext>i</mtext>}}\text{= 2·3 ± 0·1 μ}\text{m}$), gluconic acid ($\text{K}{}_{\mathrm{<mtext>i</mtext>}}\text{= 82 ± 2 μ}\text{m}$) and glucose ($\text{K}{}_{\mathrm{<mtext>i</mtext>}}\text{= 1·3 ± 0·1}\text{m}\text{m}$) appeared to be competitive inhibitors of this enzyme.     

Fermentation of table cream by Lactobacillus plantarum strains: effect on fungal growth,aflatoxin M1 and ochratoxin A

Aflatoxin M1 (AFM₁) and ochratoxin A (OTA) are two main mycotoxins in milk and dairy products. In the present work, the ability of four Lactobacillus strains (L. plantarum PTCC 1058, L. plantarum LP3, L. plantarum AF1 and L. plantarum LU5) to remove AFM1 and OTA in fermented cream was studied during 24 h fermentation. The antifungal activity of the mentioned lactobacilli against the defined fungi (Aspergillus flavus PTCC 5004, Aspergillus parasiticus PTCC 5018, Aspergillus nidulans PTCC 5014, Aspergillus ochraceus PTCC 5060) was also evaluated. The results showed that the cell counts of all strains were increased by 64–70% during fermentation. All Lactobacillus strains decreased the amount of AFM₁ significantly (P ≤ 0.05) in the range of 26–52%, which the highest AFM₁-reducing effect was related to L. plantarum LU5 (from 0.5 to 0.24 μg kg⁻¹). The mean OTA removal by Lactobacillus strains in fermented cream also ranged from 32 to 58%. Amongst Lactobacillus strains, the cell-free culture supernatants of L. plantarum LU5 showed the highest (inhibition zone of 26.7 ± 1.2 mm) and L. plantarum LP3 and L. plantarum PTCC 1058 the lowest antifungal activities. The fermented creams contained Lactobacillus strains exhibited the highest and lowest antifungal activities against A. ochraceus and A. parasiticus, respectively. L. plantarum LU5, with the inhibition zone of 27.6 ± 0.9 mm, was the most effective fungal inhibitor, while L. plantarum PTCC 1058 had the lowest antifungal activity.     

Inhibition of the activity of mushroom tyrosinase by alkylbenzoic acids

The inhibition kinetics of alkylbenzoic acids on the diphenolase activity of mushroom tyrosinase have been investigated. The results show that the alkylbenzoic acids assayed can lead to reversible inhibition of the enzyme; furthermore, o-toluic acid and m-toluic acid are mixed-type inhibitors and p-alkylbenzoic acids are uncompetitive inhibitors. The inhibition constants have been determined. For these p-alkylbenzoic acids, the inhibition strength follows the order: p-toluic acid < p-ethylbenzoic acid < p-propylbenzoic acid < p-isopropylbenzoic acid < p-tert-butylbenzoic acid < p-butylbenzoic acid < p-pentylbenzoic acid < p-hexylbenzoic acid < p-heptylbenzoic acid < p-octylbenzoic acid, indicating that the hydrophobic p-alkyl group played an important role in the inhibition of the enzyme. The inhibitory effects were potentiated with increasing lengths of the hydrocarbon chains. The inhibitory effects of o-toluic acid and p-isopropylbenzoic acid on the monophenolase activity have also been studied. The results show that both o-toluic acid and p-isopropylbenzoic acid can lengthen the lag time and decrease the steady-state activity of the enzyme.     

Structural features and hypoglycaemic effects of Cynomorium songaricum polysaccharides on STZ-induced rats

A water-soluble polysaccharide isolated from Cynomorium songaricum which is a traditional Chinese food was purified by Ultrahydrogel 500 gel filtration chromatography. The structural characterisation and hypoglycaemic activity of the purified polysaccharide fraction (CSPA) were evaluated. CSPA (M_w of 1.394 × 10⁵ Da) was a heteropolysaccharide consisting of Ara, Glu and Gal. The conformation of CSPA was characterised as a compact chain of sphere-like structure in aqueous solution with a d_f value of 2.86. Linkage analysis and NMR (1D and 2D) revealed the presence of the following unit:

→3)-α-araf-(1→3)-α-d-glcp-(1→4)-α-d-GalpA6Me-(1→$\to 3)\text{-}\alpha \text{-}\mathit{araf}\text{-}(1\to 3)\text{-}\alpha \text{-}d\text{-}\mathit{glcp}\text{-}(1\to 4)\text{-}\alpha \text{-}d\text{-Gal}p\text{A6Me-}(1\to$

Zur Kenntnis des Pyrokohlens?uredi?thylesters

Zusammenfassung Im Hinblick auf die Verwendung von Pyrokohlensäurediäthylester (PKE) zur Getränkeentkeimung wurden Untersuchungen mit PKE-(carbonyl-¹⁴C) durchgeführt. Es bestätigte sich, daß dieser Zusatzstoff in den Getränken überwiegend zu Kohlendioxid und Äthanol hydrolysiert wird. Es konnten jedoch auch Nebenreaktionen mit Getränkebestandteilen nachgewiesen werden, die einem analytischen Nachweis bisher nicht zugänglich waren. Im einzelnen ergaben sich:Der hydrolytische Zerfall des PKE in Kohlendioxid und Äthanol erfolgt in angesäuertem Wasser (PKE-Konzentration 100 mg/1) von pH 3,2 bei Zimmertemperatur exponentiell in Abhängigkeit von der Zeit mit einer Halbwertszeit von etwa 0,5 Std und verläuft quantitativ. Ein Kohlensäurepartialdruck bis zu 4 at, wie er in Limonadenflaschen erreicht werden kann, beeinflußt die Hydrolysegeschwindigkeit nicht signifikant. Abschätzungsweise mit gleicher Geschwindigkeit verläuft die Hydrolyse in allen von uns untersuchten Limonaden, Fruchtsäften und Weinen.Neben der Hydrolyse erfolgen in den Getränken in geringem Umfang Umsetzungen des PKE mit Getränkebestandteilen, insbesondere Aminosäuren. 24 Std nach Behandlung von Limonaden und Fruchtsäften (13 Sorten wurden untersucht) mit 100 mg/1 PKE-¹⁴C bei Zimmertemperatur ergaben sich nach Austreiben des radioaktiven Kohlendioxids Aktivitätsrückstände in Höhe von 0,5–3% der eingesetzten Aktivität; nur in Orangensaft wurde, sortenabhängig schwankend, ein vergleichsweise hoher Aktivitätsrückstand von 4–8% aufgefunden. Der doppelte Wert des jeweils ermittelten prozentualen Aktivitätsrückstandes gibt den prozentualen Gewichtsanteil des nicht hydrolytisch zerfallenden PKE an.In Weinen betrug der Umfang der Nebenreaktionen etwa 5–6 % der eingesetzten Aktivität, davon entfielen 2,2–3,5% auf die Bildung von Diäthylearbonat-¹⁴C, dem Umsetzungsprodukt von PKE¹⁴C mit Äthylalkohol.Die Nebenreaktionen des PKE in den Getränken erfolgen in mehr oder weniger starkem Maße mit allen Verbindungen, die eine oder mehrere freie Hydroxyl-, primäre oder sekundäre Aminogruppen enthalten. Eine Umsetzung von PKE mit Zuckern und Fruchtsäuren ist hierbei vernachlässigbar gering. In einem vergleichsweise stärkeren Maße reagieren jedoch Aminosäuren, Proteine und Gerbstoffe. Innerhalb dieser Stoffklassen ergaben sich für die einzelnen Substanzen quantitative Unterschiede hinsichtlich ihres Reaktionsvermögens mit PKE.PKE reagiert mit den einzelnen Getränkebestandteilen proportional deren Konzentration und weitgehend unabhängig von der Zahl und der Konzentration der übrigen Reaktionspartner. Damit scheint es aufgrund unserer Versuche möglich, bei bekannter Zusammensetzung der Getränke Voraussagen über das Ausmaß der PKE-Nebenreaktionen zu machen.Der Umfang der PKE-Nebenreaktionen ist in starkem Maße vom pH-Wert der Getränke abhängig. Erniedrigt man den pH-Wert der Getränke, so liefert die Umsetzung mit PKE¹⁴C merklich tiefere Aktivitätsrückstände, mit steigendem pH-Wert hingegen wächst der Umfang der Nebenreaktionen beträchtlich. Die Bestandteile der Getränke sind in unterschiedlichem Maße von dieser pH-abhängigen Reaktion mit PKE betroffen.

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Die gesammelte Literatur überEigenschaften, Wirkungsweise undAnalytik ist in dem anschließenden Übersichtsbericht als I. Mitteilung wiedergegeben.     

Inactivation of Escherichia coli O157:H7 and Salmonella spp. on alfalfa seeds by caprylic acid and monocaprylin

Alfalfa and other seed sprouts have been implicated in several Escherichia coli O157:H7 and Salmonella spp. human illness outbreaks in the U.S. Continuing food safety issues with alfalfa seeds necessitate the need for discovery and use of novel and effective antimicrobials. The potential use of caprylic acid (CA) and monocaprylin (MC) for reducing E. coli O157:H7 and Salmonella spp. populations on alfalfa seeds was evaluated. The effectiveness of three concentrations of CA and MC (25, 50, and 75 mM) to reduce E. coli O157:H7 and Salmonella spp. populations in 0.1% peptone water and on alfalfa seeds was evaluated. Surviving populations of E. coli O157:H7 and Salmonella spp. were enumerated by direct plating on tryptic soy agar (TSA). Non-inoculated alfalfa seeds were soaked for up to 120 min to evaluate the effect of CA and MC solutions on seed germination rate. For planktonic cells, the efficacy of the treatments was: 75 MC > 50 MC > 25 MC > 75 CA > 50 CA > 25 CA. Both E. coli O157:H7 and Salmonella spp. were reduced to below the detection limit (0.6 log CFU/ml) within 10 min of exposure to 75 MC from initial populations of 7.65 ± 0.10 log CFU/ml and 7.71 ± 0.11 log CFU/ml, respectively. Maximum reductions of 1.56 ± 0.25 and 2.56 ± 0.17 log CFU/g for E. coli O157:H7 and Salmonella spp., respectively, were achieved on inoculated alfalfa seeds (from initial populations of 4.74 ± 0.62 log CFU/g and 5.27 ± 0.20 log CFU/g, respectively) when treated with 75 MC for 90 min. Germination rates of CA or MC treated seeds ranged from 84% to 99%. The germination rates of CA or MC soaked seeds and water soaked seeds (control) were similar (P > 0.05) for soaking times of ≤ 90 min. Monocaprylin (75 mM) can be used to reduce E. coli O157:H7 and Salmonella spp. on alfalfa seeds without compromising seed viability.     

Monitoring of the bacterial communities of bamboo shoots (Dendrocalamus latiflorus) during pickling process

The diversity and dynamics of the dominant bacterial communities arising during the pickling process of bamboo shoots (Dendrocalamus latiflorus) were investigated by nested polymerase chain reaction denaturing gradient gel electrophoresis combined with quantitative real‐time polymerase chain reaction. Results showed only several kinds of halophilic bacteria during early sampling time (0?3 days). After pickling for 7 days, Lactococcus lactis significantly increased (P < 0.05, quantities were 6.39 × 10⁵ copies μL^?1) and became the first dominant bacterium. After pickling for 14 days, Weissella sp. bands appeared and quickly became dominant on the 21st day (4.07 × 10⁶ copies μL^?1). As maturation progressed, Lc. lactis decreased in intensity whereas Weissella sp. increased in intensity. Finally, the quantities of Weissella sp. (2.50 × 10⁷ copies μL^?1) became higher than those of Lc. lactis (1.43 × 10⁷ copies μL^?1) after pickling for 56 days. The pickling process was initiated by Lc. lactis, followed by Lc. lactis and Weissella sp., and was finally succeeded by Weissella sp.     

Use of Fourier transform infrared spectroscopy for rapid comparative analysis of Bacillus and Micrococcus isolates

The identification of foodborne microorganisms and their endospores in food products are important for food safety. The present work compares Bacillus (Bacillus licheniformis, Bacillus circulans and Bacillus subtilis) and Micrococcus (Micrococcus luteus) species with Fourier transform infrared (FTIR) spectroscopy. Our results show that there are several characteristic peaks belonging to both the Micrococcus and Bacillus species which can be used for the identification of these foodborne bacteria and their endospores. For Micrococcus species, a new band was observed at 1338 cm⁻¹ which may be due to acetate oxidation via the carboxylic acid cycle. The bands at 1313 cm⁻¹ and 1256 cm⁻¹ can be explained by an exopolymer formation and the other bands at 1074 cm⁻¹ and 550 cm⁻¹, may be due to the glycogen-like storage material in Micrococcus spp. There are also characteristic peaks at 993 cm⁻¹ and 801 cm⁻¹ for these bacterial species. Different Bacillus species also showed characteristic peaks at 1000–500 cm⁻¹ region. Dipicolinic acid (DPA) bands at ∼728 cm⁻¹ and ∼703 cm⁻¹ seen only in B. circulans were the marker of an endospore formation.     

Thermal inactivation of Yersinia enterocolitica in pork slaughter plant scald tank water

The objective of this study was to establish the time–temperature combinations required to ensure the thermal inactivation of Yersinia enterocolitica during scalding of pork carcasses. A 2 strain cocktail of Y. enterocolitica (bioserotypes 2/O:5,27 and 1A/O:6,30) was heat treated at 50, 55 and 60 °C in samples of scald tank water obtained from a commercial pork slaughter plant. Samples were removed at regular intervals and surviving cells enumerated using (i) Cefsulodin–Irgasan–Novobiocin Agar (CIN) supplemented with ampicillin and arabinose and (ii) Tryptone Soya Agar (TSA), overlaid with CIN agar with ampicillin and arabinose. The data generated was used to estimate D- and z-values and the formula D_x = log^− 1(log D₆₀ − ((t₂ − t₁)/z)) was applied to calculate thermal death time–temperature combinations from 55 to 65 °C. D₅₀, D₅₅ and D₆₀-values of 45.9, 10.6 and 2.7 min were calculated from the cell counts obtained on CIN agar, respectively. The corresponding D-values calculated from the TSA/CIN counts were 45.1, 11 and 2.5 min, respectively. The z-value was 7.8. It was concluded that a time–temperature combination of 2.7 min at 60 °C is required to achieve a 1 log reduction in Y. enterocolitica in pork scald tank water. The predicted equivalent at 65 °C was 0.6 min. This study provides data and a model to enable pork processors to identify and apply parameters to limit the risk of carcass cross-contamination with Y. enterocolitica in pork carcass scald tanks.