Food Science Commons^™

Enzymatic Synthesis Of Galactooligosaccharides From Whey Permeate, Federica Manucci

Masters

Galactooligosaccharides (GOS) are prebiotics that have a beneficial effect on human health by promoting the growth of probiotic bacteria in the gut. GOS are commonly produced from lactose in a reaction catalysed by β-galactosidase, termed transglycosylation. In the present work the synthesis of GOS from Whey Permeate (WP) using commercially available β-galactosidases was studied. The enzymes used were from Kluyveromyces lactis (Maxilact® L2000) and Escherichia coli. Initially, a novel quantitative TLC-based assay to monitor GOS synthesis was developed. This method was employed for kinetic analysis but precision and bias problems in quantification were observed. An HPLC assay was subsequently developed …

The Effects Of Acid Adaptation On Escherichia Coli Inactivation Using Power Ultrasound, Sonal Patil, Paula Bourke, Bridget Cullen, Jesus Maria Frias, Patrick Cullen

Articles

Inactivation of Escherichia coli in liquids was carried out using power ultrasound. Parameters examined included amplitude levels (0.4µm, 7.5 µm, 37.5 µm), treatment time, cell condition (non-adapted cells, acid adapted cells), liquid media (TSB, model orange juice and model apple juice) and E. coli strain (ATCC 25922, NCTC 12900). The efficacy of ultrasound treatment was found to be a function of amplitude level, treatment time and media (p0.95), with the highest inactivation achieved using an amplitude of 37.5 µm. The D-values of E. coli 25922 at all amplitudes in model orange juice were not significantly different than in TSB media. …

Modelling Browning And Brown Spotting Of Mushrooms (Agaricus Bisporus) Stored In Controlled Environmental Conditions Using Image Analysis, Catherine Barry-Ryan, Jesus Maria Frias, Leixuri Aguirre, Helen Grogan

Articles

Mushrooms have a short postharvest shelf life compared to most vegetables, due to a very high metabolic activity and high water content, making them prone to microbial spoilage and to exhibit enzymatic browning. Storage conditions and natural product variability are both important factors that affect the management of mushrooms, and both of them can be managed using monitoring systems. In order to study the effect of the temperature and relative humidity on the whiteness decrease and appearance of brown spotting, an image analysis system was employed. Twenty five batches of mushrooms were subjected to combinations of three storage temperatures (T) …

Orange Juices Enriched With Chitosan: Optimisation For Extending The Shelf-Life, Catherine Barry-Ryan, Ana Belen Martin-Diana, Daniel Rico, J. Barat

Articles

Optimisation of the incorporation of chitosan in orange juice was accomplished by the evaluation of quality and nutritional markers. Response surface methodology was applied to obtain quadratic and second degree response surface model equations. The analyses showed that increases in chitosan concentration extended the quality of the orange juice significantly (p < 0.05), reducing enzymatic and non-enzymatic browning and controlling the spoilage during the storage time; however, concentrations N 1 g L− 1 produced a significant (p < 0.05) reduction in the concentrations of ascorbic acid and carotenoids associated with the positive charge of chitosan and its ability to flocculate and coagulate negatively charged substances. Also, concentrations N 1 g L− 1 were scored as unacceptable for the sensory panel due to an increase in bitterness. The study recommends the use of chitosan at concentrations up to 1 g L− 1 to extend quality and preserve ascorbic acid and carotenoids during storage time of fresh orange juice, thus avoiding the use of standard thermal treatments which produces a negative impact on the nutritional value. Industrial relevance: One of the major problems of fresh orange juice is its limited shelf-life. Spoilage and quick degradation of vitamins are two of the most important causes of quality loss during the shelf-life of this product. Moreover, the U. S. Food and Drug Administration issued a warning to consumers against drinking unpasteurised orange juice products because of the potential contamination with Salmonella typhimurium and its association with an outbreak of human disease caused by this organism [FDA issues nationwide health alert on Orchid Island unpasteurised orange juice. Products Recalls, Market Withdrawals and Safety Alerts.]. The main objective of this study was the study of chitosan as a natural preservative for extending the shelf-life of orange juice and as an alternative to pasteurisation.

Identification Of Volatile Quality Markers Of Ready-To-Use Lettuce And Cabbage, Catherine Barry-Ryan, Michael Devereux, Julien Lonchamp

Articles

Volatile emission changes of ready-to-use vegetables directly result from minimal processing and can reflect the sensory changes occurring in the product. Based on the detection of key volatile compounds, novel on-line and consumer quality-monitoring methods can be developed. The aim of this study was to identify volatile biomarkers for a range of leafy green ready-to-use vegetables (Butterhead and Iceberg lettuce and Irish York cabbage). Headspace volatile compounds were monitored using gas chromatography/mass spectrometry (GC/MS). The sensory quality of the products was evaluated at days 1, 7 and 14 using sensory and analytical measurements. Changes of volatile concentrations and sensory attributes …

Impact Of Plant Essential Oils On Microbiological, Organoleptic And Quality Markers Of Minimally Processed Vegetables, Jorge Gutierrez, Paula Bourke, Julien Lonchamp, Catherine Barry-Ryan

Articles

The objectives of this study were to evaluate the efficacy of plant essential oils (EOs) for control of the natural spoilage microflora on ready-to-eat (RTE) lettuce and carrots whilst also considering their impact on organoleptic properties. Initial decontamination effects achieved using EOs were comparable to that observed with chlorine and solution containing oregano recorded a significantly lower initial TVC level than the water treatment on carrots (p < 0.05). No significant differences were found between the EO treatments and chlorine considering gas composition, color, texture and water activity of samples. The sensory panel found EO treatments acceptable for carrots throughout storage, while lettuce washed with the EO solutions were rejected for overall appreciation by Day 7. Correlating microbial and sensory changes with volatile emissions identified 12 volatile quality markers. Oregano might be a suitable decontamination alternative to chlorine for RTE carrots, while the identification of volatile quality markers is a useful complement to sensory and microbiological assessments in the monitoring of organoleptic property changes and shelf-life of fresh vegetables. Industrial relevance There is industrial demand for natural alternatives to chlorine, which is commonly used for decontamination of fresh produce but which has limitations with respect to antimicrobial efficacy and possible formation of carcinogenic compounds in water. Plant essential oils have proven antimicrobial and other bioactive properties, however their usefulness in foods can be mitigated by their high sensory impact. This study examined the application of EOs for fresh produce decontamination addressing control of spoilage microflora and improving shelf-life characteristics whilst also considering the impact on organoleptic properties. The effectiveness of oregano as a decontamination treatment was comparable with that of chlorine. Carrot discs treated with the EO regimes were acceptable in terms of sensory quality and appreciation, therefore oregano could offer a natural alternative for the washing and preservation of fresh produce. Combining EOs with other natural preservatives might minimize doses and reduce the impact on organoleptic properties of fresh vegetables.

Extrinsic Control Parameters For Ozone Inactivation Of Escherichia Coli Using A Bubble Column, Sonal Patil, Patrick Cullen, Bridget Cullen, Jesus Maria Frias, Paula Bourke

Articles

Aims: To investigate the effect of extrinsic control parameters for ozone inactivation of E. coli in a bubble column. Methods and Results: Ozone inactivation of Escherichia coli ATCC 25922 in Tryptic Soya Broth was examined. The parameters studied included temperature (ambient, 20, 25 and 30°C), exposure time (up to 30 min), gas flow rate (0·03, 0·06, 0·12, 0·25, 0·5 and 0·75 l min−1) and concentration level (five different levels). The efficacy of ozone treatment was a function of the parameters investigated and optimum control parameters of flow rate (0·12 l min−1), temperature (ambient) and ozone concentration (75 μg ml−1) resulted …

Antimicrobial Activity Of Plant Essential Oils Using Food Model Media: Efficacy, Synergistic Potential And Interaction With Food Components, Jorge Gutierrez, Catherine Barry-Ryan, Paula Bourke

Articles

The aim of this study was to optimise the antimicrobial efficacy of plant essential oils (EOs) for control of Listeria spp. and spoilage bacteria using food model media based on lettuce, meat and milk. The EOs evaluated were lemon balm, marjoram, oregano and thyme and their minimum inhibitory concentrations (MIC) were determined against Enterobacter spp., Listeria spp., Lactobacillus spp., and Pseudomonas spp. using the agar dilution method and/or the absorbance based microplate assay. MICs were significantly lower in lettuce and beef media than in TSB. Listeria strains were more sensitive than spoilage bacteria, and oregano and thyme were the most …

An Investigation Of The Sensory Properties Of Legumes As Influenced By Irish Consumer's Knowledge And Acceptance., Anne O'Leary, Therese G. Cadden, Ivano Caprioli

Conference papers

The health benefits related to legume consumption are many and varied, however the acceptability of this nutritive food has received very little attention.

The aim of this research is to investigate consumer knowledge of the health benefits associated with regular consumption of legumes and to explore consumer acceptability of legumes.

The study highlights how recipe formulation, consumption patterns, health behaviour and sensory properties all intertwine to shape an individuals acceptance of legumes.

Detection Of Numerous Verotoxigenic E. Coli Serotypes, With Multiple Antibiotic Resistance From Cattle Faeces And Soil, L. Scott, P. Mcgee, Ciara Walsh, Seamus Fanning, T. Sweeney, J. Blanco, M. Karczmarczyk, B. Earley, N. Leonard, J.J. Sheridan

Articles

Verotoxigenic E. coli (VTEC) belong to a diverse range of serotypes. Serotypes O157 and O26 are predominately identified in VTEC-associated disease in Europe, however due to difficulty in detection little is known about the epidemiology of non-O157 serotypes. This study reports the identification of 7 VTEC serotypes from cattle faeces and soil. Cattle faeces samples (n = 128) were taken from animals in 6 different farms, with soil samples (n = 20) obtained from 1 farm. After sample incubation in modified tryptone soy broth (mTSB) supplemented with streptomycin sulphate samples were plated onto sorbitol MacConkey (SMAC) also supplemented …

Inactivation Of Escherichia Coli In Orange Juice Using Ozone, Sonal Patil, Paula Bourke, Jesus Maria Frias, Brijesh Tiwari, Patrick Cullen

Articles

This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10⁶ CFU mL^-1) as a challenge microorganism was treated with ozone at 75-78µg mL^-1 for different time periods (0-18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500mm or 1mm sieves. Fast inactivation rates for total reduction of E. coli …

Application Of Natural Antimicrobials For Food Preservation, Brijesh Tiwari, Vasilis Valdramidis, Colm O' Donnell, Kasiviswanathan Muthukumarappan, Patrick Cullen, Paula Bourke

Articles

In this review, antimicrobials from a range of plant, animal, and microbial sources are reviewed 10 along with their potential applications in food systems. Chemical and biochemical antimicrobial 11 compounds derived from these natural sources and their activity against a range of pathogenic and 12 spoilage microorganisms pertinent to food, together with their effects on food organoleptic proper- 13 ties, are outlined. Factors influencing the antimicrobial activity of such agents are discussed 14 including extraction methods, molecular weight, and agent origin. These issues are considered in 15 conjunction with the latest developments in the quantification of the minimum inhibitory (and …