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.

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).

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.

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.

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.

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B(1) production of Fusarium verticillioides and F. proliferatum on corn. Part I: the effect of initial headspace carbon dioxide concentration.

The effect of modified atmospheres on the growth and fumonisin B(1) production of Fusarium verticillioides and Fusarium proliferatum on corn is presented in a series of two papers. In this, the first part, the effect of initial headspace (IH) carbon dioxide concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was evaluated. It was observed that at all a(w) values studied, increase in the IH CO(2) concentration generally resulted in a decrease in the colony growth rate (g, mm day(-1)) and maximum colony diameter (D(max), mm) and an increase in the lag phase duration (lambda, day). Although both a(w) and IH CO(2) concentration had significant and synergistic effects on g, a(w) had the largest effect. As little as 10% IH CO(2) completely inhibited the production of fumonisin B(1) by F. verticillioides. F. proliferatum was more resistant and required 40, 30 and 10% IH CO(2) at a(w) 0.984, 0.951 and 0.930, respectively, to completely inhibit fumonisin B(1) production. These results demonstrate that modified atmospheres containing high CO(2) levels could potentially be employed for the protection of corn from fungal spoilage and mycotoxin contamination during the post-harvest period.

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B(1) production of Fusarium verticillioides and F. proliferatum on corn. Part II: The effect of initial headspace oxygen concentration.

This paper is the second in a series of two that describe the effect of modified atmospheres on the growth and mycotoxin production of Fusarium verticillioides and Fusarium proliferatum on corn. In this part, the effect of initial headspace (IH) oxygen concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was investigated. In addition, the impact of vacuum packaging and in-cooperation of O(2) scrubbing sachets was also studied. It was observed that at all a(w) values studied, reduction of IH O(2) concentration from 20 to 2% had no significant effect on the colony growth rate (g, mm d(-1)) and lag phase duration (lambda, d). However, g and lambda were positively and negatively correlated to a(w). The IH O(2) concentration was determined to have a a(w) dependent effect on the oxygen consumption rate. Although the maximum colony diameter (D(max), mm) decreased with the reduction of the IH O(2) level, the greatest mycelial density occurred at 10% IH O(2) for both isolates. This observation was accompanied by a trend of a decrease in the value of the IH O(2) level at which the most fumonisin B(1) was produced from 15 to 5% when the a(w) was decreased from 0.976 to 0.930 for F. verticillioides. For F. proliferatum the optimum conditions for fumonisin B(1) production shifted from 20% at a(w) 0.976 to 10% at both 0.951 and 0.930. Vacuum packaging and the in-cooperation of O(2) absorbing sachets completely inhibited the growth of both isolates. These results together with those reported in Part I of the study indicate that O(2) should preferably be completely excluded from modified atmospheres that are employed to protect stored corn from fungal growth and mycotoxin production.

Interaction of water activity and bicarbonate salts in the inhibition of growth and mycotoxin production by Fusarium and Aspergillus species of importance to corn.

The combined effects of water activity (a(w)) and ammonium/sodium bicarbonate on growth and mycotoxin production in corn by Fusarium and Aspergillus species were investigated. Interaction was observed between the salts and a(w) on the colony growth rates and lag phase durations of all isolates. Growth stimulation at low salt levels was observed only for the Fusarium isolates as the fastest growth of F. verticillioides and F. proliferatum occurred at levels of 0.1-0.2 and 0.5% ammonium and sodium bicarbonate, respectively. Although the complete inhibition of the growth of the Fusarium and Aspergillus isolates investigated took place at a level of 1% ammonium bicarbonate as much as 4% sodium bicarbonate failed to completely inhibit the growth of the Aspergillus isolates. Increase in concentration of either salt generally resulted in large reductions of both fumonisin B(1) and aflatoxin B(1) production. According to the sensorial analysis performed, corn treated with up to 1% ammonium bicarbonate was still acceptable for consumption, whereas corn treated with at least 2% sodium bicarbonate was determined to be sensorially unsuitable. Ammonium bicarbonate can be concluded to be more suitable for protecting stored corn from fungal contamination as it was capable of completely inhibiting both growth and mycotoxin production of the Fusarium and Aspergillus isolates of most importance to corn at levels that were still sensorially acceptable. Therefore ammonium bicarbonate could possibly be applied as a cheap and easy to apply treatment for use in resource limited developing countries.

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.

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.

Predictive modelling of the individual and combined effect of water activity and temperature on the radial growth of Fusarium verticilliodes and F. proliferatum on corn.

The major objective of this study was to develop validated models to describe the effect of a(w) and temperature on the radial growth on corn of the two major fumonisin producing Fusaria, namely Fusarium verticilliodes and F. proliferatum. The growth of these two isolates on corn was therefore studied at water activities between 0.810-0.985 and temperatures between 15 and 30 degrees C. Minimum a(w) for growth was 0.869 and 0.854 for F. verticilliodes and F. proliferatum, respectively. No growth took place at a(w) values equal to 0.831 and 0.838 for F. verticilliodes and F. proliferatum, respectively. The colony growth rates, g (mm d(-1)) were determined by fitting a flexible growth model describing the change in colony diameter (mm) with respect to time (days). Secondary models, relating the colony growth rate with a(w) or a(w) and temperature were developed. A third order polynomial equation and the linear Arrhenius-Davey model were used to describe the combined effect of temperature and a(w) on g. The combined modelling approaches, predicting g (mm d(-1)) at any a(w) and/or temperature were validated on independently collected data. All models proved to be good predictors of the growth rates of both isolates on maize within the experimental conditions. The third order polynomial equation had bias factors of 1.042 and 1.054 and accuracy factors of 1.128 and 1.380 for F. verticilliodes and F. proliferatum, respectively. The linear Arrhenius-Davey model had bias factors of 0.978 and 1.002 and accuracy factors of 1.098 and 1.122 for F. verticilliodes and F. proliferatum, respectively. The results confirm the general finding that a(w) has a greater influence on fungal growth than temperature. The developed models can be applied for the prevention of Fusarium growth on maize and the development of models that incorporate other factors important to mould growth on maize.

Combined liquid and gas chromatographic characterisation of polyglycerol fatty acid esters.

In the present study a combined liquid and gas chromatographic technique is described for the analysis of polyglycerol fatty acid esters. Liquid chromatographic fractionation of samples resulted in pure standards of monoesters of di- and triglycerols and diesters of di- and triglycerols. Confirmation of their identity was achieved by LC-MS analysis. Moreover, a chromatographic identification of the mono- and diesters of cyclic diglycerol was proposed. From the isolation of pure esters and their gas chromatographic analysis, it was revealed that co-elution of several compounds occurred. Thus it was shown that prefractionation of the sample using a simplified liquid chromatographic separation, was necessary in order to characterise the esters correctly. In combination with some other chemical analyses, a complete profile of the chemical composition of polyglycerol fatty acid esters can be obtained.

Influence of acetate and CO2 on the TMAO-reduction reaction by Shewanella baltica.

In this work, the TMAO-reduction by Shewanella baltica, one of the representative spoilage organisms in modified atmosphere packaged marine fish fillets, and the effect of acetate and CO2 on this reduction were studied in vitro. The growth of S. baltica and the corresponding evolution of some compounds (acetate, lactate, pyruvate, glucose and trimethylamine (TMA)) were followed during storage at 4 degrees C in two types of broths. The first medium was a defined medium (pH = 6.8) to which lactate or pyruvate was added as hydrogen donor. Pyruvate showed to be more efficient as H-donor for S. baltica than lactate, as growth was much faster when equimolar amounts of pyruvate instead of lactate were present. Although the growth of S. baltica, when pyruvate is used as H-donor and no acetate is added, was not much inhibited by the CO2-atmosphere, CO2 had a pronounced effect on the studied reactions as it partly inhibited the reduction of pyruvate to acetate. The effect of acetate on this reaction was, on the other hand, not significant. To simulate the reactions occurring in situ, a buffered fish extract (pH = 6.8) was used. In spite of the neutral pH, the growth of S. baltica in this medium was highly inhibited by relatively small concentrations of acetate (< 0.3%). When 0.1% of acetate was added to the fish extract, less acetate was formed and lactate was more slowly consumed in comparison to the experiments without the addition of acetate. The consumption of lactate and the production of acetate were almost completely inhibited when the fish extract contained 0.25% of acetate. Apparently, the addition of acetate inhibited the use of lactate as H-donor. After extended storage times (17 days at 4 degrees C) TMA production started. Most probably, alternative H-donors were used by S. baltica, from which the pathway seems to be less energy efficient. This can be deduced from the exceptional growth inhibition of S. baltica by small amounts of acetate. However, when practical storage times for fish (e.g. 6 days at 4 degrees C after packaging) are considered, growth and TMAO-reduction by S. baltica was completely inhibited during this period by 0.25% of acetate.