Yeast Strain Influences the Hop-Derived Sensory Properties and Volatile Composition of Beer.

The perception of hop-derived flavour in beer is not well understood, particularly regarding the effect that different yeast strains and fermentation parameters have on perceived hop aroma and the mechanisms responsible for these changes. To evaluate the influence of yeast strain on the sensory properties and volatile composition of beer, a standard wort, late-hopped with New Zealand Motueka hops (5 g·L), was fermented with one of twelve yeast strains under constant conditions (temperature and yeast inoculation rate). The bottled beers were evaluated using a free sorting sensory methodology, and their volatile organic compounds (VOC) were assessed using gas chromatography mass spectrometry (GC/MS) with headspace solid-phase microextraction (SPME) sampling.

Non-permanent primary food packaging materials assessment: Identification, migration, toxicity, and consumption of substances.

Almost all processed food comes packaged in either plastic, glass, metal, or paper and paperboard materials, and many packaging materials are disposed of after a single use (linear economy). Based on the concept of a circular economy, the recycling of food packaging materials has become one of the main targets for industries and regulators around the world. However, recycling presents particular challenges, mainly related to the recycled material composition, which determines its reusability, application, functionality, and chemical safety.

Comparing Taste Detection Thresholds across Individuals Following Vegan, Vegetarian, or Omnivore Diets.

Taste perception plays an undisputed role in food choice, preference, and intake. Recent literature suggests that individual diet and taste sensitivity may have a reciprocal relationship, with evidence highlighting that specific diets can alter taste sensitivities. Commensurate with an increase in the prevalence of plant-based diets is the importance of investigating if following a vegetarian or vegan diet is associated with altered taste sensitivities.

Bacterial survival and adhesion for formulating new oral probiotic foods.

Probiotics are defined as live microorganisms, which, when administered in adequate amounts, confer health benefits to the host. Traditionally, probiotic food research has heavily focused on the genera and , along with their benefits for gut health. Recently with the identification of new probiotic strains specifically intended for oral health applications, the development of probiotic foods for oral health benefits has garnered interest, with a renewed focus on identifying new food formats for delivering probiotics.

Differential gene expression for investigation of the effect of germinants and heat activation to induce germination in Bacillus cereus spores.

Differential gene expression was used to explore the mechanisms underpinning the differences in the impact of heat activation (70 °C for 30 min) on the germination of Bacillus cereus spores in the presence and absence of a germinant (L-alanine). The number of germinated cells, after heat activation plus L-alanine (3.5 ± 0.

Effect of cold storage and different ions on the thermal resistance of B. cereus NZAS01 spores- analysis of differential gene expression and ion exchange.

Bacillus cereus spores in food are able to survive pasteurization, and if conditions are favourable, subsequently germinate, grow and produce toxins causing food poisoning. The objectives of this study were to firstly determine the impact of cold storage and ion uptake on the thermal resistance of B. cereus spores and secondly to use differential gene expression to help elucidate possible molecular mechanisms for the changes detected in their thermal resistance.

Development of a novel sample reuse approach to measure the impact of lean meat, bone and adipose tissue on the development of volatiles in vacuum-packed chilled lamb stored at 2 °C for 15 days.

The impact of different ratios of lean meat, adipose tissue (fat) and bone on the volatile organic compound (VOC) profile of vacuum-packed (VP) lamb stored at 2 °C for up to 15 days was investigated using two sampling approaches. VOC development in individual samples was followed over time using either a traditional sampling regime where replicate samples were sampled (single-use) at a given time or a novel approach where replicate samples were resampled (reuse) over time. VOCs present in the headspace of the packaged samples were detected using proton-transfer-reaction mass spectrometry (PTR-MS) with complementary solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS) analysis on a subset of samples.

Impact of temperature, nutrients, pH and cold storage on the germination, growth and resistance of Bacillus cereus spores in egg white.

B. cereus spores are a concern to the food industry, especially to the producers of heat sensitive food products like egg white or precooked and stored food such as fried rice. This study investigated the impact of nutrients, temperature (4, 8, 15 and 25 °C), pH (4, 5, 7 and 9), and cold storage on the germination, growth and resistance of B.

Comparison of four extraction methods for analysis of volatile hop-derived aroma compounds in beer.

The volatile organic compound profile in beer is derived from hops, malt, yeast, and interactions between the ingredients, making it very diverse and complex. Due to the range and diversity of the volatile organic compounds present, the choice of the extraction method is extremely important for optimal sensitivity and selectivity. This study compared four extraction methods for hop-derived compounds in beer late hopped with Nelson Sauvin.

Comparing PTR-MS profile of milk inoculated with pure or mixed cultures of spoilage bacteria.

The volatile organic compounds (VOCs) associated with UHT milk (n=8) inoculated with either pure inoculums of Pseudomonas fluorescens (two strains tested) or Chryseobacterium sp., or with mixed cultures of 2 or all 3 of the bacterial strains, and held at 4.5 °C for up to 26 days was measured using proton transfer reaction - mass spectrometry (PTR-MS).

Investigating the in-vitro and in-vivo flavour release from 21 fresh-cut apples.

In-vitro and in-vivo flavour release from 21 different apple cultivars was studied using proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) with a focus on the relationship between texture and volatile organic compound (VOC) emission. Generally, firm-juicy cultivars had a shorter time to first swallow (Tswal) and a higher number of swallows (Nswal), while softer-mealy cultivars had a longer Tswal and a lower Nswal. Firm-juicy cultivars containing high VOC concentrations had a short time to maximum intensity (Tmax) owing to a shorter Tswal and a higher Nswal as juice was released during mastication.

Monitoring photooxidation-induced dynamic changes in the volatile composition of extended shelf life bovine milk by PTR-MS.

Exposure of milk to light leads to photooxidation and the development of off-flavours. To follow these reactions, semi-skimmed (1.5% fat) and whole (3.

X-ray micro-computer tomographic method to visualize the microstructure of different apple cultivars.

Apples are appreciated for their texture with firmness acting as an indicator of quality. During prolonged storage, apples can soften and their texture can become undesirably mealy. Using an X-ray microcomputer tomography (μ-CT) scanner, the porosity (ratio of intercellular space [IS] to total volume) and the structural arrangement of the parenchyma tissue of 4 apple cultivars (Braeburn, Fuji, Golden Delicious, Jazz) stored under similar conditions for 100 d were visualized via the development of 2D and 3D images.

Antibiotic susceptibility of Moraxella catarrhalis biofilms in a continuous flow model.

Antibiotic susceptibility of Moraxella catarrhalis biofilms was assessed using a Sorbarod filter continuous flow model. Ceftriaxone, erythromycin, amoxicillin, and Augmentin produced significant decreases in both biofilm and planktonic viable cell populations collected from the effluent. Augmentin produced the greatest reduction in biofilm (2.

In vitro and in vivo flavor release from intact and fresh-cut apple in relation with genetic, textural, and physicochemical parameters.

Unlabelled: Flavor release from 6 commercial apple cultivars (Fuji, Granny Smith, Golden Delicious, Jonagold, Morgen Dallago, and Red Delicious) under static conditions (intact or fresh-cut samples) and during consumption of fresh-cut samples (nosespace) was determined by proton transfer reaction mass spectrometry. Textural (firmness, fracturability, flesh elasticity, and rupture) and physicochemical (pH, acidity, and water content) properties of the apples were also measured. Static headspace analysis of intact fruits revealed Fuji and Granny Smith apples had the lowest concentration for all measured flavor compounds (esters, aldehydes, alcohols, and terpenes), whereas Red Delicious apples had the highest.

Histamine stability in Rihaakuru at -80, 4 and 30°C.

Rihaakuru is a shelf stable fish paste product formed from a fish soup prepared from tuna. Histamine contamination is a food safety issue with this product that is manufactured from tuna fish that has been temperature abused. Histamine concentrations decreased between 31% and 73% in Rihaakuru stored for 10months at either -80, 4 or 30°C.

Biogenic amines and potential histamine - Forming bacteria in Rihaakuru (a cooked fish paste).

The biogenic amine concentration in Rihaakuru (a fish paste) (n=28), obtained from different parts of the Maldives (North, South, and Central), was determined by HPLC. Ten biogenic amines were detected; agmatine, not detected (ND) - 161ppm; cadaverine, ND - 387ppm; histamine, ND - 5487ppm; putrescine, ND - 290ppm; phenylethylamine, ND - 23ppm; serotonin, ND - 91ppm; spermine, ND - 329ppm; spermidine, ND - 79ppm; tryptamine, ND - <5ppm; and tyramine, ND - 50ppm. Nine biogenic amines were found in 3 samples, 8 in 10 samples, 7 in 6 samples, 6 in 3 samples, 4 in 5 samples, and 1 was found in 1 sample.

The physico-chemical characterization of casein-modified surfaces and their influence on the adhesion of spores from a Geobacillus species.

To gain a better understanding of the factors influencing spore adhesion in dairy manufacturing plants, casein-modified glass surfaces were prepared and characterized and their effect on the adhesion kinetics of spores from a Geobacillus sp., isolated from a dairy manufacturing plant (DMP) was assessed using a flow chamber. Surfaces were produced by initially silanizing glass using (3-glycidyloxypropyl) trimethoxysilane (GPS) or (3-aminopropyl) triethoxysilane to form epoxy-functionalized (G-GPS) or amino-functionalized glass (G-NH(2)) substrata.

Chemistry and microbiology of traditional Rihaakuru (fish paste) from the Maldives.

Rihaakuru is a traditional Maldivian side dish consumed mainly with rice. It is a thick brown fish paste, made from tuna after prolonged heating. Samples tested were found to have a low water activity (0.

Salt modulates bacterial hydrophobicity and charge properties influencing adhesion of Pseudomonas aeruginosa (PA01) in aqueous suspensions.

The influence on cell hydrophobicity of differential extension with ionic strength of lipopolysaccharide molecules (LPS), which exist as charged and uncharged polymers at the surface of the gram-negative bacterium Pseudomonas aeruginosa (PA01), has been investigated. Attenuated total reflection infrared (ATR-IR) spectral absorptions from a single layer of cells adsorbed to ZnSe increased in intensity with increasing NaCl concentration up to 0.1 mol L(-1).

Structure and conformation in mixtures of methyl-terminated poly(ethylene oxide) and water. Principal component analysis and band fitting of infrared absorptions.

Infrared absorption spectra of aqueous mixtures of poly(ethylene oxide) dimethyl ether (PEO), with a number average molecular weight of 500 and a water volume fraction between 0 and 0.96 have been recorded at 18, 26, and 40 degrees C. Composition and temperature were found to influence the intensity and wavenumber of PEO-related absorptions.

Adhesive secretions of live mussels observed in situ by attenuated total reflection-infrared spectroscopy.

The chemical species involved in the adhesion of blue mussels (Mytilus galloprovincialis) and greenshell mussels (Perna canaliculus) to surfaces has been investigated using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. Mussel spat ranging in size from 0.5 to 25 mm were placed in a flow cell containing a ZnSe multiple internal reflection prism and supplied with temperature-controlled seawater.

Acid-base titrations of functional groups on the surface of the thermophilic bacterium Anoxybacillus flavithermus: comparing a chemical equilibrium model with ATR-IR spectroscopic data.

Acid-base functional groups at the surface of Anoxybacillus flavithermus (AF) were assigned from the modeling of batch titration data of bacterial suspensions and compared with those determined from in situ infrared spectroscopic titration analysis. The computer program FITMOD was used to generate a two-site Donnan model (site 1: pKa = 3.26, wet concn = 2.

Infrared spectroscopic studies of siderophore-related hydroxamic acid ligands adsorbed on titanium dioxide.

The adhesion of bacteria to metal oxide and other mineral surfaces may involve bacterial siderophores, many of which contain hydroxamic acid (Ha) ligands. The adsorption behavior of the siderophore-related ligands acetohydroxamic acid, N-methylformohydroxamic acid, N-methylacetohydroxamic acid, and 1-hydroxy-2-piperidone on titanium dioxide thin films has been investigated using in situ ATR-IR spectroscopy with variation of concentration and pH. All the ligands were found to adsorb strongly on the TiO2 surface as hydroxamate ions and form bidentate surface complexes.

Monitoring metal ion binding in single-layer Pseudomonas aeruginosa biofilms using ATR-IR spectroscopy.

The binding of metal ions to Pseudomonas aeruginosa PAO1 cells attached to a ZnSe surface has been observed in this research through cation exchange experiments using ATR-IR spectroscopy. A biofilm consisting of a single layer of Pseudomonas aeruginosa PAO1 cells was formed on a ZnSe prism by flowing a bacterial suspension in a 0.03 mol L(-)(1) NaNO(3) solution at pH 5.