The pathogenic and spoilage bacteria associated with red meat and application of different approaches of high CO2 packaging to extend product shelf-life.

With the fast-global development of packaging techniques, the potential antimicrobial effect of CO2, as a safe, cheap and readily available gas, makes it the integral component for packaging of meat products. The associated spoilage and/or pathogenic bacteria on raw meat may respond in different ways to elevated CO2 concentrations. The growth of some aerobic Gram-negative bacteria such as Pseudomonas spp. is significantly inhibited but some LAB bacteria may be allowed to grow faster and dominate the product. The antimicrobial efficacy of enriched CO2 packaging is attributed to the rate of CO2 solubility in the product which is itself affected by the level of headspace CO2, product pH, temperature and the ratio of headspace gas to product (G:P). This review, first, explores the varied range of beef and sheep meat spoilage and pathogenic bacteria and the intrinsic and extrinsic parameters that may influence the pattern of microbial growth and meat spoilage rate during storage. Then, the antimicrobial mechanism of elevated CO2 packaging will be discussed and the different approaches of achieving enriched CO2 packaging i.e. the traditional technique of flushing a desired gas mixture and/or using the new commercially developed CO2 emitters will then be compared in terms of their strengths, limitations and technical mode of action.

Identifying Chemical Differences in Cheddar Cheese Based on Maturity Level and Manufacturer Using Vibrational Spectroscopy and Chemometrics.

Cheese is a nutritious dairy product and a valuable commodity. Internationally, cheddar cheese is produced and consumed in large quantities, and it is the main cheese variety that is exported from Australia. Despite its importance, the analytical methods to that are used to determine cheese quality rely on traditional approaches that require time, are invasive, and which involve potentially hazardous chemicals. In contrast, spectroscopic techniques can rapidly provide molecular information and are non-destructive, fast, and chemical-free methods. Combined with partner recognition methods (chemometrics), they can identify small changes in the composition or condition of cheeses. In this work, we combined FTIR and Raman spectroscopies with principal component analysis (PCA) to investigate the effects of aging in commercial cheddar cheeses. Changes in the amide I and II bands were the main spectral characteristics responsible for classifying commercial cheddar cheeses based on the ripening time and manufacturer using FTIR, and bands from lipids, including ß'-polymorph of fat crystals, were more clearly determined through changes in the Raman spectra.

Microbial biopreservatives for controlling the spoilage of beef and lamb meat: their application and effects on meat quality.

Biopreservation is a recognized natural method for controlling the growth of undesirable bacteria on fresh meat. It offers the potential to inhibit spoilage bacteria and extend meat shelf-life, but this aspect has been much less studied compared to using the approach to target pathogenic bacteria. This review provides comprehensive information on the application of biopreservatives of microbial origin, mainly bacteriocins and protective cultures, in relation to bacterial spoilage of beef and lamb meat. The sensory effect of these biopreservatives, an aspect that often receives less attention in microbiological studies, is also reviewed. Microbial biopreservatives were found to be able to retard the growth of the major meat spoilage bacteria, Brochothrix thermosphacta, Pseudomonas spp., and Enterobacteriaceae. Their addition did not have any discernible negative impact on the sensory properties of meat, whether assessed by human sensory panels or instrumental and chemical analyses. Although results are promising, the concept of biopreservation for controlling spoilage bacteria on fresh meat is still in its infancy. Studies in this area are still lacking, especially for lamb. Biopreservatives need more testing under conditions representative of commercial meat production, along with studies of any possible sensory effects, in order to validate their potential for large-scale industrial applications.

Meat texture modification for dysphagia management and application of hydrocolloids: A review.

Dysphagia is a medical condition that describes the difficulty of swallowing food, and texture modified food (TMF) is the best intervention for dysphagia. The relevant guidelines to identify dysphagia food are provided by the International Dysphagia Diet Standardization Initiative (IDDSI). Developing texture modified meat is a challenging task due to its fibrous microstructure and harder texture. Various meat tenderization attempts are therefore evaluated in the literature. Meat texture modification for dysphagia is not just limited to tenderization but should be focused on safe swallowing attributes as well. The application of hydrocolloids for designing TMF has a major research focus as it is a cost-effective method and offers an opportunity for careful control. The present review focuses on the meat texture modification attempts that have been used in the past and present, with special attention to the use of hydrocolloids. Several studies have shown improvements in texture upon the addition of various hydrocolloids; however, few studies have attempted to develop texture modified meat for people with dysphagia. This area has to be further developed along with the sensory evaluations conducted with the dysphagia population, to validate the industrial application of hydrocolloids to TMF.

Quantitation of carotenoids and fatty acids from Atlantic salmon using a portable Raman device.

Raman spectroscopy can be a useful tool for performing non-destructive subsurface measurements, allowing for investigations on intact foods that would otherwise require food products to be prepared for analysis, thus creating food waste, and often requiring the addition of chemicals. To overcome this, we have developed a method to measure the concentration of pigment (astaxanthin) and fatty acids in whole, unfilleted Atlantic salmon through the skin using defocused Raman spectroscopy. Subsurface measurements were performed across different regions of Atlantic salmon. PLS regression of the measured spectra gave a moderate correlation between Raman bands and astaxanthin concentration (R2 = 0.5797) and good correlations for fatty acid concentrations (total, saturated, monounsaturated, polyunsaturated, trans; R2 = 0.7457 to 0.8249). This work shows that subsurface Raman measurements can provide useful quantitative information regarding important quality parameters (pigment and fatty acid concentrations) that can aid with production in aquaculture.

High moisture extrusion cooking of meat analogs: A review of mechanisms of protein texturization.

High-moisture extrusion cooking (HMEC) is an efficient method for converting proteins and polysaccharides into fibrous structure that is used in the industrial production of meat analogs. The purpose of this review is to systematically evaluate current knowledge regarding the modification of protein structure including denaturation and reassembly upon extrusion processing and to correlate this understanding to the structure of the final products. Although there is no consensus on the relative importance of a certain type of bond on extrudates' structure, literature suggests that, regardless of moisture level, these linkages and interactions give rise to distinctive hierarchical order. Both noncovalent and disulfide bonds contribute to the extrudates' fibrous structure. At high water levels, hydrogen and disulfide bonds play a dominant role in extrudates' texture. The process parameters including cooking temperature, screw speed, and moisture content have significant albeit different levels of impact on the texturization process. Their correlation with the ingredients' physiochemical properties provides a greater insight into the process-structure-function relationship of meat analogs. The tendency of protein and polysaccharide blends to phase separate rather than produce a homogeneous mix is a particularly important aspect that leads to the formation of fibrous layers when extruded. This review shows that systematic studies are required to measure and explain synergistic and competitive interactions between proteins and other ingredients such as carbohydrates with a focus on their incompatibility. The wide range of plant protein source can be utilized in the HMEC process to produce texturized products, including meat analogs.

Detection of Biomarkers Relating to Quality and Differentiation of Some Commercially Significant Whole Fish Using Spatially Off-Set Raman Spectroscopy.

Aquaculture represents a major part of the world's food supply. This area of food production is developing rapidly, and as such the tools and analytical techniques used to monitor and assess the quality of fish need to also develop and improve. The use of spatially off-set Raman spectroscopy (SORS) is particularly well-suited for these applications, given the ability of this technique to take subsurface measurements as well as being rapid, non-destructive and label-free compared to classical chemical analysis techniques. To explore this technique for analysing fish, SORS measurements were taken on commercially significant whole fish through the skin in different locations. The resulting spectra were of high quality with subsurface components such as lipids, carotenoids, proteins and guanine from iridophore cells clearly visible in the spectra. These spectral features were characterised and major bands identified. Chemometric analysis additionally showed that clear differences are present in spectra not only from different sections of a fish but also between different species. These results highlight the potential application for SORS analysis for rapid quality assessment and species identification in the aquaculture industry by taking through-skin measurements.

Investigation of chemical composition of meat using spatially off-set Raman spectroscopy.

Spatially off-set Raman spectroscopy (SORS) offers non-invasive chemical characterisation of the sub-surface of various biological tissues as it permits the assessment of diffusely scattering samples at depths of several orders of magnitude deeper than conventional Raman spectroscopy. Chemicals such as glycogen, glucose, lactate and cortisol are predictors of meat quality, however detection of these chemicals is limited to the surface of meat using conventional Raman spectroscopy as their concentration is higher within the tissue. Here, we have used SORS to detect spectral bands for glycogen, lactate, glucose and cortisol beneath the surface of meat tissue by spiking. To our knowledge, this is the first report on this method for potential application in meat quality analysis. We further validate our SORS spectral results using chemometric analysis to determine chemical-specific spectral characteristics suitable for chemical identification. The chemometric analysis clearly shows distinction of spiked metabolites into four distinct groups, even for such chemically similar compounds as glucose, glycogen and lactate.

Harvesting and blending options for lower alcohol wines: a sensory and chemical investigation.

BACKGROUND: Lower alcohol wines often have a poor reputation among consumers, in part due to their unsatisfactory flavours such as reduced overall aroma intensity or herbaceous characters. The aim of this study, performed on Verdelho and Petit Verdot, was to quantify the effectiveness of a monovarietal blend in which wines made from less ripe grapes were blended with an equivalent volume of a wine vinified from riper fruit to produce wines with a lower alcohol content and desirable ripe fruit flavours. RESULTS: Eleven and 13 attributes, for Verdelho and Petit Verdot, respectively, were selected during sensory descriptive analysis. Intensities of perceived 'acidity', 'sweetness' and 'alcohol' attributes were significantly different (P ≤ 0.05) between the blend (8.8 ± 0.1% v/v) and mature Verdelho (10.3 ± 0.1% v/v) wines, while no significant differences were found between the Petit Verdot blend (11.0 ± 0.1% v/v) and mature (12.6 ± 0.2% v/v) treatments. Volatile composition of wines was assessed using HS-SPME-GC-MS. Partial least square regression suggested relationships between sensory descriptors and chemical attributes in the wines, as well as the modifications of sensory and compositional profiles following blending. CONCLUSIONS: The blending practice described allowed the production of wines with lower alcohol content while retaining similar sensory profiles of the later harvested, riper fruit wines. © 2017 Society of Chemical Industry.

Changes in volatile composition and sensory attributes of wines during alcohol content reduction.

A desirable sensory profile is a major consumer driver for wine acceptability and should be considered during the production of reduced-alcohol wines. Although various viticultural practices and microbiological approaches show promising results, separation technologies such as membrane filtration, in particular reverse osmosis and evaporative perstraction, in addition to vacuum distillation, represent the most common commercial methods used to produce reduced-alcohol wine. However, ethanol removal from wine can result in a significant loss of volatile compounds such as esters (ethyl octanoate, ethyl acetate, isoamyl acetate) that contribute positively to the overall perceived aroma. These losses can potentially reduce the acceptability of the wine to consumers and decrease their willingness to purchase wines that have had their alcohol level reduced. The change in aroma as a result of the ethanol removal processes is influenced by a number of factors: the type of alcohol reduction process; the chemical-physical properties (volatility, hydrophobicity, steric hindrance) of the aroma compounds; the retention properties of the wine non-volatile matrix; and the ethanol level. This review identifies and summarises possible deleterious influences of the dealcoholisation process and describes best practice strategies to maintain the original wine composition. © 2016 Society of Chemical Industry.

Australian consumers' attitudes to packaged fresh meat products with added microbial bioprotective cultures for shelf-life extension.

The application of food-grade microbial cultures to fresh meat products is a promising natural approach for meat shelf-life extension. However, before its adoption into commercial practice, it is essential to understand consumers' attitudes to this approach and the resulting marketed products. This study investigated Australian consumers' willingness to purchase and consume packaged fresh meat products with added microbial cultures for shelf-life extension. A national online survey of over 800 respondents was conducted. Results indicated that most Australian consumers would be willing to buy and eat such products, with 17.8% of respondents less likely to buy and 11.1% unwilling to eat these products. Respondents' purchasing and consumption decisions were influenced by demographic factors, their food and meat shopping and consumption behaviors, and the value, taste, and type of the meat product. Consumer acceptance may be improved by increasing their awareness of the potential use of microbial cultures as natural antimicrobials for food shelf-life extension.

Investigation of the effects of addition of carboxy methyl cellulose (CMC) and tapioca starch (TS) on the beef patties targeted to the needs of people with dysphagia: A mixture design approach.

The D - optimal mixture design was used to optimize inclusions of hydrocolloids [carboxy methyl cellulose (CMC) 0-1% w/w, and tapioca starch (TS) 0-1% w/w] to create beef patties as a soft & bite-size food (level 6) according to the international dysphagia Diet Standardisation Initiative (IDDSI) guidelines. The effect of each ingredient and combination, on cooking properties and textural characteristics, were analysed. Results revealed that a combination of CMC and TS helped to improve the cooking yield and texture of beef patties. Optimization of ingredients obtained according to the maximum cooking yield, optimum colour, soft texture as per the IDDSI guidelines. Optimum formulation of patty contained beef 88.57%, CMC 0.89% and TS 0.02% with 0.87 desirability score. The beef patties containing hydrocolloids complied with the IDDSI fork pressure test. This test is recommended as a way to identify soft and bite-size foods for people with dysphagia.

Relationship between instrumental and sensory texture profile of beef semitendinosus muscles with different textures.

Texture of meat is a critical factor in oral processing and bolus formation, especially for people suffering from dysphagia. The present study evaluated and compared the texture changes of beef semitendinosus muscles upon cooking, using sensory panelists and instrumental texture profile analysis. Cooking losses were also estimated. The correlation between instrumental and sensory parameters were established. Training with sensory texture profile enabled panelists to clearly identify and describe meat textural attributes except cohesiveness and springiness. Increased cooking temperature (65-85°C) and time (30-60 min) significantly (p < .05) increased hardness, chewiness, and cook loss of beef whereas adhesiveness and juiciness decreased significantly. The correlation data showed significant positive correlations between instrumental and sensory hardness, chewiness, and adhesiveness and poor correlations between cohesiveness and springiness. Results show that the texture profile analyzer has a possibility to replace sensory analysis for hardness, chewiness, and adhesiveness; however, future work is needed to address cohesiveness and springiness of meat.

Evaluation of the potential of protective cultures to extend the microbial shelf-life of chilled lamb meat.

The use of protective cultures to inhibit spoilage bacteria is a promising natural preservation technique to extend the shelf-life of fresh meat. This study evaluated the effectiveness of six food-grade protective cultures (containing different combinations of Lactobacillus sakei, Pediococcus pentosaceus, Staphylococcus xylosus, and Staphylococcus carnosus) on naturally contaminated chill-stored (4 °C) lamb meat in different packaging systems. Only slight reductions of common meat spoilage bacteria Brochothrix thermosphacta, Pseudomonas spp., and Enterobacteriaceae were observed in culture-treated samples stored in modified atmosphere packaging (80% O2:20% CO2). Greater inhibitory effects were found in vacuum-packed lamb, with mixed cultures containing either L. sakei, S. carnosus, and S. xylosus or S. carnosus and L. sakei causing the most significant reductions. Protective cultures did not adversely affect meat color or pH. This study demonstrated the potential of protective cultures comprising lactic acid bacteria and coagulase-negative staphylococci in controlling microbial spoilage of lamb and, by inference, other types of meat as a natural solution for shelf-life extension.

Relationship between masticatory variables and bolus characteristics of meat with different textures.

The physiological transformations that happen during oral processing are complex and challenging to capture and measure; however, their knowledge can help design new products for people who struggle with mastication and swallowing. Here we relate chewing, saliva incorporation and bolus properties with initial meat texture. Three different textures (T1-tender, T2-intermediate, T3-tough) were created by cooking meat in different temperature time combinations and "ready-to-swallow" meat boluses were collected from 10 healthy individuals. Masticatory variables, saliva incorporation, and bolus mechanical and geometrical characteristics were analyzed. Meat texture showed significant effect on masticatory variables (number of chews and chewing duration) but not on saliva incorporation. Bolus mechanical characteristics (hardness, cohesiveness and adhesiveness) varied significantly (p < .05) with meat texture, where meat with a harder texture resulted in a harder bolus. Number of bolus particles changed significantly (p < .05) with increasing meat hardness, where harder meat produced more bolus particles. Significant (p < .05) intersubject variability was recorded for masticatory parameters and saliva incorporation. Mechanical and geometrical characteristics of "ready-to-swallow" meat bolus did not vary among subjects.

Assessment of the potential use of MALDI-TOF MS for the identification of bacteria associated with chilled vacuum-packaged lamb meat.

The focus of this study was to compare the effectiveness of MALDI-TOF MS and partial 16S rRNA gene sequencing for the identification of bacteria isolated from VP lamb meat stored chilled at 5 °C for 21 days, at the same time gaining insights into bacterial changes over time. The identity of bacterial isolates on non-selective and selective agars was determined by both methods and results compared. Results showed that total bacterial numbers increased over the 21 days (as expected) with Staphylococcus and Pseudomonas (day 0) being replaced by Carnobacterium, Brochothrix and members of the Enterobacteriaceae family by day 21. A high level of agreement (86-100%) for bacterial isolates' identity at genus level was observed between MALDI-TOF MS and partial 16S rRNA gene-based sequencing for isolates where identification was possible. With its cheaper cost and faster turnaround time, once optimized, MALDI-TOF MS could become a useful alternative to 16S rRNA gene-sequencing for the rapid identification of red meat bacterial isolates.

Volatile and sensory profiling of Shiraz wine in response to alcohol management: comparison of harvest timing versus technological approaches.

The aim of this study was to compare the volatile and sensory profiles of Australian Shiraz red wines produced by several methods to achieve alcohol concentrations of 10.5 and 13.5% v/v. These levels were considerably lower contents than the commercial wine (16-17% v/v) that was produced from this vineyard site. Wines were produced by: (i) harvest timing (19.3, 24 and 29.3 Brix); (ii) blending equal proportions of early harvest (19.3 Brix) and late harvest wines (29.3 Brix); and (iii) dealcoholization using reverse osmosis followed by a membrane contactor. Dealcoholization caused a significant loss of volatile compounds, particularly esters, while the blending treatment had an averaging effect on most analytes. Sensory descriptive analysis of treatments with 10.5% v/v alcohol showed that the perception of the herbaceous attribute was more intense in the early harvest wines in comparison to the dealcoholized wines, while those of dark fruit, raisin/prune, astringency and alcohol were lower. No sensory differences were found amongst the 13.5% v/v wines, except for alcohol. Sensory and compositional data were modelled by means of Common Dimension (ComDim) multi-block analysis and indicated which chemical components are important to the perceived wine sensory properties. Insights from this study will provide knowledge that may be applied to control or moderate both unripe sensory attributes in addition to a deficiency of ripe fruit aromas or mouthfeel characteristics in reduced-alcohol red wines.

A comparative study of partial dealcoholisation versus early harvest: Effects on wine volatile and sensory profiles.

Two Verdelho and Petit Verdot wines were produced from sequential harvests of grapes. The alcohol concentration of early harvest (EH) and late harvest (LH) wines were respectively 9% and 13.5% v/v for Verdelho, and 10.5% and 13% v/v for Petit Verdot. LH wines were dealcoholised to match the same alcohol level of EH samples using a combined reverse osmosis-evaporative perstraction process. In dealcoholised wines, there was a decrease in volatile compounds (esters particularly) compared to LH treatments. For both varieties, the sensory attribute ratings for overall aroma intensity and alcohol mouthfeel also decreased following dealcoholisation. Dealcoholised wines were distinctively different from both LH and EH wines even though these wines had similar alcohol level to EH wines. When dealcoholisation is considered for high-alcohol wines, it is important to consider that membrane effects can significantly change depending on the wine non-volatile matrix composition and the level of alcohol reduction required.