Spoilage evaluation of raw Atlantic salmon (Salmo salar) stored under modified atmospheres by multivariate statistics and augmented ordinal regression.

The development of quality monitoring systems for perishable food products like seafood requires extensive data collection under specified packaging and storage conditions, followed by advanced data analysis and interpretation. Even though the benefits of using volatile organic compounds as food quality indices have been recognized, few studies have focused on real-time quantification of the seafood volatilome and subsequent systematic identification of the most important spoilage indicators. In this study, spoilage of Atlantic salmon (Salmo salar) stored under modified atmospheres (% CO2/O2/N2) and air was characterized by performing multivariate statistical analysis and augmented ordinal regression modelling for data collected by microbiological, chemical and sensory analyses. Out of 25 compounds quantified by selected-ion flow-tube mass spectrometry, ethanol, dimethyl sulfide and hydrogen sulfide were found characteristic under anaerobic conditions (0/0/100 and 60/0/40), whereas spoilage under air was primarily associated with the production of alcohols and ketones. Under high-O2 MAP (60/40/0), only 3-methylbutanal fulfilled the identification criteria. Overall, this manuscript presents a systematic and widely applicable methodology for the identification of most potential seafood spoilage indicators within the context of intelligent packaging technology development. In particular, parallel application of statistics and modelling was found highly beneficial for the performance of the quality characterization process and for the practical applicability of the obtained results in food quality monitoring.

Microbiological, chemical and sensory spoilage analysis of raw Atlantic cod (Gadus morhua) stored under modified atmospheres.

During fish spoilage, microbial metabolism leads to the production of volatile organic compounds (VOCs), characteristic off-odors and eventual consumer rejection. The aim of the present study was to contribute to the development of intelligent packaging technologies by identifying and quantifying VOCs that indicate spoilage of raw Atlantic cod (Gadus morhua) under atmospheres (%v/v CO2/O2/N2) 60/40/0, 60/5/35 and air. Spoilage was examined by microbiological, chemical and sensory analyses over storage time at 4 or 8 °C. Selected-ion flow-tube mass spectrometry (SIFT-MS) was used for quantifying selected VOCs and amplicon sequencing of the 16S rRNA gene was used for the characterization of the cod microbiota. OTUs classified within the Photobacterium genus increased in relative abundance over time under all storage conditions, suggesting that Photobacterium contributed to spoilage and VOC production. The onset of exponential VOC concentration increase and sensory rejection occurred at high total plate counts (7-7.5 log). Monitoring of early spoilage thus calls for sensitivity for low VOC concentrations.

Isoepoxydon dehydrogenase (idh) gene expression in relation to patulin production by Penicillium expansum under different temperature and atmosphere.

Penicillium expansum growth and patulin production occur mainly at post-harvest stage during the long-term storage of apples. Low temperature in combination with reduced oxygen concentrations is commonly applied as a control strategy to extend apple shelf life and supply the market throughout the year. Our in vitro study investigated the effect of temperature and atmosphere on expression of the idh gene in relation to the patulin production by P. expansum. The idh gene encodes the isoepoxydon dehydrogenase enzyme, a key enzyme in the patulin biosynthesis pathway. First, a reverse transcription real-time PCR (RT-qPCR) method was optimized to measure accurately the P. expansum idh mRNA levels relative to the mRNA levels of three reference genes (18S, ß-tubulin, calmodulin), taking into account important parameters such as PCR inhibition and multiple reference gene stability. Subsequently, two P. expansum field isolates and one reference strain were grown on apple puree agar medium (APAM) under three conditions of temperature and atmosphere: 20 °C - air, 4 °C - air and 4 °C - controlled atmosphere (CA; 3% O2). When P. expansum strains reached a 0.5 and 2.0 cm colony diameter, idh expression and patulin concentrations were determined by means of the developed RT-qPCR and an HPLC-UV method, respectively. The in vitro study showed a clear reduction in patulin production and down-regulation of the idh gene expression when P. expansum was grown under 4 °C - CA. The results suggest that stress (low temperature and oxygen level) caused a delay of the fungal metabolism rather than a complete inhibition of toxin biosynthesis. A good correlation was found between the idh expression and patulin production, corroborating that temperature and atmosphere affected patulin production by acting at the transcriptional level of the idh gene. Finally, a reliable RT-qPCR can be considered as an alternative tool to investigate the effect of control strategies on the toxin formation in food.

Acrylamide mitigation strategies: critical appraisal of the FoodDrinkEurope toolbox.

FoodDrinkEurope Federation recently released the latest version of the Acrylamide Toolbox to support manufacturers in acrylamide reduction activities giving indication about the possible mitigation strategies. The Toolbox is intended for small and medium size enterprises with limited R&D resources, however no comments about the pro and cons of the different measures were provided to advise the potential users. Experts of the field are aware that not all the strategies proposed have equal value in terms of efficacy and cost/benefit ratio. This consideration prompted us to provide a qualitative science-based ranking of the mitigation strategies proposed in the acrylamide Toolbox, focusing on bakery and fried potato products. Five authors from different geographical areas having a publication record on acrylamide mitigation strategies worked independently ranking the efficacy of the acrylamide mitigation strategies taking into account three key parameters: (i) reduction rate; (ii) side effects; and (iii) applicability and economic impact. On the basis of their own experience and considering selected literature of the last ten years, the authors scored for each key parameter the acrylamide mitigation strategies proposed in the Toolbox. As expected, all strategies selected in the Toolbox turned out to be useful, however, not at the same level. The use of enzyme asparaginase and the selection of low sugar varieties were considered the best mitigation strategies in bakery and in potato products, respectively. According to authors' opinion most of the other mitigation strategies, although effective, either have relevant side effects on the sensory profile of the products, or they are not easy to implement in industrial production. The final outcome was a science based commented ranking which can enrich the acrylamide Toolbox supporting individual manufacturer in taking the best actions to reduce the acrylamide content in their specific production context.

THE INFLUENCE OF SALT CONTENT AT DIFFERENT CONCENTRATIONS OF TERASI TO THE SENSORY CHARACTERISTICS OF SAMBAL TERASI, THE CHILI SAUCE ADDED WITH TERASI.

The type of terasi (the Indonesian seafood fermented paste) and the ingredients used can give sambal terasi (ST), the chili sauce added with terasi, its identity and taste distinction. Inherit from its production, salt content differs the flavor(s) of product added with terasi. This research explored the role of terasi salt content, either from the origin of terasi or by salt adjustment, to the products acceptability and sensory characteristics perceived during subsequent sensorial evaluations. Six types of terasi were characterized based on the proximate and salt content, and prepared as STs with and without salt adjustment at several terasi concentrations. 118 panelists conducted sensory evaluations for overall acceptability at 12.5% terasi; at lower concentration specific tastes (sweet, bitter, salty, sour, umami, fishy and rebon) were characterized by 80 panelists. Results showed that the acceptance of ST is more due to its innate origin salt content and to the suitability saltiness perceived. The specific odor of terasi, combining with other taste(s), when prepared at higher terasi concentration as practiced in restaurant, home and commercial products showed masking effect(s). After saltiness adjusted, different types of terasi showed different taste characteristics. Preferred ST were different between higher and lower concentration. Better tastes characteristics and stronger spices taste were found at lower salt content (and terasi concentration).

MALDI-based identification of stable hazelnut protein derived tryptic marker peptides.

Food allergy is an important health problem especially in industrialised countries. Tree nuts, among which are hazelnuts (Corylus avellana), are typically causing serious and life-threatening symptoms in sensitive subjects. Hazelnut is used as a food ingredient in pastry, confectionary products, ice cream and meat products, therefore undeclared hazelnut can be often present as a cross-contaminant representing a threat for allergic consumers. Mass spectrometric techniques are used for the detection of food allergens in processed foods, but limited information regarding stable tryptic peptide markers for hazelnut is available. The aim of this study was to detect stable peptide markers from modified hazelnut protein through the Maillard reaction and oxidation in a buffered solution. Peptides ³95Gly-Arg4°³ from Cor a 11 and ²°9Gln-Arg²¹7, ³5¹Ile-Arg³6³, 464Ala-Arg478 and 4°¹Val-Arg4¹7 from Cor a 9 hazelnut allergens proved to be the most stable and could be detected and confirmed with high scores in most of the modified samples. The identified peptides can be further used as analytical targets for the development of more robust quantitative methods for hazelnut detection in processed foods.

Age-dependent sensitization to the 7S-vicilin-like protein Cor a 11 from hazelnut (Corylus avellana) in a birch-endemic region.

BACKGROUND: Hazelnut (Corylus avellana) allergy exhibits age and geographically distinct sensitization patterns that have not yet been fully resolved. OBJECTIVE: To study sensitization to Cor a 11 in different age groups of hazelnut-allergic patients and infants with atopic dermatitis (AD) sensitized to hazelnut in a birch-endemic region. METHODS: Sera from 80 hazelnut-allergic patients, 33 infants under 1 year of age with AD (24 sensitized and 9 not sensitized to hazelnut), 32 healthy control individuals, and 29 birch pollen-allergic but hazelnut-tolerant individuals were tested for immunoglobulin (Ig) E reactivity to Cor a 11 by ImmunoCAP. IgE reactivity to Cor a 1.01, Cor a 1.04, Cor a 8, and Cor a 9 was studied by ISAC microarray. RESULTS: Forty patients (22 preschool children, 10 schoolchildren, and 8 adults) with systemic reactions on consumption of hazelnut were sensitized to Cor a 11 (respective rates of 36%, 40%, and 12.5%). Forty patients (6 preschool children, 10 schoolchildren, and 24 adults) reported oral allergy syndrome but only 2 of them (of preschool age) were sensitized to Cor a 11. Two (8%) of the AD infants sensitized to hazelnut showed IgE reactivity to Cor a 11. This reactivity was not observed in any of the AD infants without sensitization to hazelnut, in any of the birch-pollen allergic patients without hazelnut allergy, or in any of the healthy control individuals. CONCLUSION: Sensitization to Cor a 11 in a birch-endemic region is predominantly found in children with severe hazelnut allergy, a finding that is consistent with observations concerning sensitization to Cor a 9.

Effect of protein glycation in the presence or absence of wheat proteins on detection of soybean proteins by commercial ELISA.

Soybean (Glycine max) is the world's primary provider of protein and oil and is widely used in foodstuffs. However, the use of soybean in foodstuffs might pose a serious threat to allergic consumers since some proteins can cause allergic reactions. To date mostly ELISA methods are used for testing contamination of foodstuffs with soybean. In view of the complexity regarding allergen detection in foodstuffs and appropriate food product labelling, the aim of this study was to investigate the impact of the Maillard reaction on the detectability of soybean proteins using commercial ELISA kits. Accumulation of protein-bound carbonyls, modification of reactive lysine residues and severe aggregation as a result of incubation with glucose, in the presence or absence of soluble wheat proteins, were recorded. Moreover, detection of soybean proteins by means of three commercial ELISA kits was strongly altered and was highly dependent on the type of kit used.

ELISA detection of hazelnut proteins: effect of protein glycation in the presence or absence of wheat proteins.

Hazelnuts are widely used in the food industry, especially confectionary foods. Nevertheless, these nuts contain several allergenic proteins that may be unexpectedly present as contaminants in various foods and may pose a serious threat to allergic consumers. The enzyme-linked immunosorbent assay (ELISA) is the preferred method to assess the level of hazelnut protein contamination. It is commonly used by both the food industry and enforcement agencies. Several ELISA kits are commercially available. However, protein detectability by ELISA may be affected by severe changes that proteins undergo during processing. The aim of this study is therefore to investigate the impact of processing on the ability to detect hazelnut protein by four commercial ELISA kits. Hazelnut proteins in the presence or absence of soluble wheat proteins were modified with glucose via the Maillard reaction. Changes in hazelnut proteins, such as the formation of protein-bound carbonyls, losses of reactive lysine residues and free amino groups, and severe aggregation dramatically affected the hazelnut protein detection by the commercial kits. The observed impact was highly dependent on the type of ELISA kit used.

Assessment of the acrylamide intake of the Belgian population and the effect of mitigation strategies.

The acrylamide (AA) intake of the Belgian consumer was calculated based on AA monitoring data of the Belgian Federal Agency for the Safety of the Food Chain (FASFC) and consumption data of the Belgian food consumption survey coordinated by the Scientific Institute for Public Health (3214 participants of 15 years or older). The average AA exposure, calculated probabilistically, was 0.4 microg kg(-1) body weight (bw) day(-1) (P97.5 = 1.6 microg kg(-1) bw day(-1)), the main contributors to the average intake being chips (23%), coffee (19%), biscuits (13%), and bread (12%). Additionally, the impact of a number of AA mitigation scenarios was evaluated (German minimization concept, scenarios for mitigation from the literature, signal values), which is an important issue for public health as well as for policy-makers. Specific actions in cooperation with the food industry to reduce the AA content of foods seems to be a more efficient strategy than mere implementation of signal values. Considering that an important share of the AA intake is due to prepared meals, the catering industry as well as consumers need to be better informed on the various possibilities for keeping the AA content of meals as low as possible.

Optimization and evaluation of a decontamination step with peroxyacetic acid for fresh-cut produce.

Since several disadvantages are associated with the use of sodium hypochlorite as a decontamination agent, the attention for alternative agents such as peroxyacetic acid (PAA) is increasing. In this study the effectiveness of PAA to remove the native microflora was tested in four types of fresh-cut vegetables: grated carrots, fresh-cut white cabbage, iceberg lettuce and leek. Furthermore, the influence of varying PAA concentrations (0, 25, 80, 150 and 250 ppm) and varying contact times (1, 5 and 10 min) was described by means of a linear model. The efficiency of PAA to remove the native flora was highly dependent on the type of fresh-cut produce: the highest microbial reductions were obtained for carrots (0.5-3.5 log cfu/g) and white cabbage (0.5-3.5 log cfu/g) followed by iceberg lettuce (0.4-2.4 log cfu/g). The obtained efficiency was the lowest for fresh-cut leek (0.4-1.4 log cfu/g). Furthermore, all the treated samples, regardless of the type of vegetable and the contact time and concentration of the PAA treatment, were acceptable for consumption.

Effects of food composition on the inactivation of foodborne microorganisms by chlorine dioxide.

Chlorine dioxide (ClO2) is a strong oxidizing agent that can be applied in solution as well as in the gaseous state. It has bactericidal, fungicidal and viricidal properties. Several food-related microorganisms, including Gram-negative and Gram-positive bacteria, yeasts, mould spores and Bacillus cereus spores were tested for their susceptibility to 0.08 mg/L gaseous ClO2 during 1 min at a relative humidity of 90%. In this screening, the resistance of the different groups of microorganisms towards gaseous ClO2 generally increased in the order Gram-negative bacteria, Gram-positive bacteria, yeasts and mould spores and Bacillus cereus spores. With this treatment, reductions of microbial numbers between 0.1 and 3.5 log cfu/cm2 could be achieved. The effects of the food components starch, fat, protein and NaCl on the antimicrobial activity of gaseous ClO2 were also evaluated. Soluble starch, corn oil, butter, whey protein isolate and NaCl were added in incremental concentrations to portions of an agar medium. Then, plates of the supplemented agars were inoculated with Leuconostoc mesenteroïdes at numbers of 4 log cfu/cm2 and subsequently treated with ClO2. Both soluble starch and NaCl did not have an effect on the antimicrobial efficiency of ClO2. However, butter, corn oil or whey protein in the agar almost eliminated the antimicrobial effect of ClO2. In corn oil-water emulsions treated with gaseous ClO2 the peroxide value increased significantly, indicating the formation of primary oxidation products. Similarly, a treatment with ClO2 increased the protein carbonyl content and induced the transformation of SH-groups to -S-S-groups in whey protein. The findings suggest that gaseous ClO2 will be a highly effective decontaminating agent for carbohydrate-rich foods, but that it would be less effective for the decontamination of high-protein and fatty foods.