Evolution of volatile compounds and biogenic amines throughout the shelf life of marinated and salted anchovies (Engraulis encrasicolus)

The use of a novel smartphone testing platform for the development of colorimetric sensor receptors for food spoilage

This work presents a novel smartphone testing platform for the validation of colorimetric sensor receptors (CSRs) in the form of layers that enables reliable and straightforward determination of their color change in a closed system using a commercially available color sensor. The food-compatible model CSR used for the method development was made of black carrot extract and ethyl cellulose. The colorimetric responses were studied in detail for NH₃, dimethylamine (DMA), and trimethylamine (TMA) by analyzing changes in the value of the total color difference (ΔE) with the increasing logarithm of the mass concentration (log γ) of the analytes. The method was partially validated for the detection limit (LOD), the limit of quantification, sensitivity, and linear γ range. The fastest reaction times were obtained for the NH₃ analyte, while the calculated LOD values were quite similar (1.48 mg L^-1 for NH₃, 1.55 mg L^-1 for DMA, and 1.58 mg L^-1 for TMA). The applicability of CSRs was shown for different types of muscle food. Frozen (boneless and skinless) hake fillets were used for additional experimental work in which the color changes of the CSRs were correlated with the values of the total volatile basic nitrogen (TVB-N) and the total counts of aerobic and anaerobic microorganisms. The developed testing platform shows great promise for the development of CSRs that define the quality of a broad variety of muscle food.

Volatile compounds, physicochemical and sensory characteristics of Colatura di Alici, a traditional Italian fish sauce

BACKGROUND

The present study reports for the first time the physical, chemical and sensory characterization of a traditional fish sauce from Italy, called 'Colatura di Alici', which is considered to be the direct descendant of the ancient roman sauce 'Garum'.

RESULTS

Among the volatile compounds, carboxylic acids, aldehydes, sulphuric compounds and pyrazines were identified. The most abundant compounds identified were 3-methyl-butanoic acid, nonanal and 3-methyl-butanal. The sample A had the highest amount of volatile fatty acids (>250 μg kg^-1 ) and sample B had the highest concentration of aldehydes (>80 μg kg^-1 ). These volatile compounds arise from the long fermentation activity and oxidation of fatty acids of the fish flesh and are responsible for the strong cheesy and fishy aroma. The protein content ranged from 90 to 130 g kg^-1 , and the soluble solids ranged from 30 to 38 °Brix, as a result of the high amount of NaCl used during processing. The sensory analysis showed a great intensity for the cheesy, fishy and umami attributes, and a medium intensity for the roasted and meaty attributes.

CONCLUSION

For the first time, the volatile compounds and sensory characteristics of this traditional fish sauce are reported. The samples differ in terms of sensory and aromatic profiles. These differences are probably linked to the poorly standardized methods used in the production process. Overall, the results of the present study could be used by local fish sauce producers to monitor the quality of the product and to improve the production process. © 2020 Society of Chemical Industry.

Comprehensive profiling of lipid oxidation volatile compounds during storage of mayonnaise

Lipid oxidation is a primary cause of quality deterioration in mayonnaise that leads to a decrease in the nutritional and sensorial value. The evolution of volatile oxidation compounds in sunflower oil mayonnaise stored at varying temperatures for 92 days and the antioxidative effect of butylated hydroxyanisole were investigated by static headspace extraction and separation by two dimensional gas chromatography/time-of-flight mass spectrometry. Considerable differences in the headspace composition of samples stored at 4, 25 and 38 °C were found due to the different oxidation levels reached. The content of hexanal in mayonnaise at 1-5 days of storage at 38 °C could be used to predict the corresponding compound in mayonnaise at 1-62 days of storage at 25 °C. The 10 most important discriminating volatile compounds during lipid oxidation of mayonnaise (at 38 °C for 92 days) are 3-hexenal, pentanal, 2-heptenal, 2-ethylfuran, hexanal, benzeneacetaldehyde, 2-pentylfuran, 3-methylhexane, 1-pentanol and 2,4-heptadienal. More than half of these compounds have a close relationship with the initial content of linoleic acid that agrees with the fatty acid profile of sunflower oil (~ 70% linoleic acid). These volatiles could be used as additional markers of oxidation in sunflower oil mayonnaise.

Determination of Volatile Components from Live Water Lily Flowers by an Orthogonal-Array-Design-Assisted Trapping Cell

A convenient and easy-moving, modified, headspace solid-phase microextraction (HS-SPME) device was developed for monitoring a living plant’s volatile organic compounds (VOCs). It consisted of a polyethylene terephthalate (PET) bottle as a sampling chamber, and certain variables were considered when using the HS-SPME device, including the material used and the fiber position, the direction of the airstream, and the distance between the sample and the fan. The results from varying those factors, generated by the orthogonal array design (OAD) method, were used to optimize the modified HS-SPME conditions. Based on the current literature regarding extracting fragrances by SPME, we selected polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polydimethylsiloxane (PDMS) as the fiber materials. Using the OAD method, PDMS/DVB was found to be the better fiber material when it was parallel to the fan, and also when the airstream provided positive pressure to the sample with the fan near the sample. The device was used to sample biogenic volatile compounds emitted from fresh Nymphaea caerulea (water lily) flowers, followed by gas chromatography-mass spectrometry (GC-MS) analysis. For the method validation, under the optimum conditions, the calculated detection limit value of the model compound (butyl decanoate) was 0.14 ng on column, which was equal to 1.41 ppm for the injection. The relative standard deviations of the intra-day and inter-day precisions were 1.21% and 3.05%. Thirty-three compounds were separated and identified. The main components in the vapor phase of N. caerulea were benzyl acetate (10.4%), pentadecane (15.5%), 6,9-heptadecadiene (40.1%), and 8-heptadecene (15.3%).

Mixed Starter Culture Regulates Biogenic Amines Formation via Decarboxylation and Transamination during Chinese Rice Wine Fermentation

The utilization of amine-negative starter based on an understanding of nitrogen metabolism is a useful method for controlling biogenic amine (BA) in Chinese rice wine (CRW) fermentation. The contribution of brewing materials to protein degradation was analyzed; wheat Qu protein had no effect, and yeast autolysis generated 10% amino nitrogen. Milling degree of rice was strongly correlated with BAs formation ( R² = 0.99). Subsequently, Lactobacillus plantarum and Staphylococcus xylosus were coinoculated as amine-negative starter at an optimized ratio of 1:2. Coinoculation induced a significant reduction in total BAs (43.7%, 44.5 mg L^-1), putrescine (43.0%, 20.4 mg L^-1), tyramine (42.8%, 14.3 mg L^-1), and histamine (42.6%, 3.5 mg L^-1) content. Notably, BAs degradation ability of Staphylococcus xylosus was stronger than the suppression effect of Lactobacillus plantarum, and higher lactic acid bacteria (LAB) amount has a positive correlation with lower BAs content. Overall, mixed strains exerted a synergistic effect in lowering BAs accumulation via decarboxylation and transamination.

Changes in Postfermentation Quality during the Distribution Process of Anchovy ( Engraulis japonicus) Fish Sauce

In the present study, we evaluated the changes in quality that can occur during the distribution of nonheated anchovy ( Engraulis japonicus) fish sauce after packaging. The pH values of all samples ranged from 5.5 to 5.8, and there were no significant differences ( P > 0.05) in pH among the samples during storage regardless of storage temperature or salt concentration. The initial total volatile base nitrogen concentration in all samples after bottling was 115 to 121 mg/100 mL, but this concentration increased gradually with storage time. After 1 year of storage, total volatile base nitrogen concentration had increased to approximately 170% of the initial concentration (166 to 194 mg/100 mL). Amino nitrogen increased slightly during storage but was significantly lower than the increase in amino nitrogen during general anchovy fish sauce fermentation with anchovy flesh. Most of the free amino acids increased slightly during the storage period regardless of storage temperature or salt concentration, but tyrosine and histidine increased and then decreased during the storage period. The histamine concentration of the anchovy fish sauce at a salt concentration of 20% was 43.3 mg/100 mL initially, but after 1 year the histamine concentration was 89.7 mg/100 mL in samples stored at 10°C, 102.6 mg/100 mL in samples stored at 25°C, and 116.8 mg/100 mL in samples stored at 35°C . Changes in putrescine and cadaverine concentrations were similar to those in histamine; concentrations increased about twofold from the initial concentrations after 1 year of storage. However, the rate of increase in putrescine from 4 months after storage was very high, and cadaverine slightly decreased by 12 months of storage. High scores for umami and aroma sensory characteristics were given to samples stored at 10°C, but samples stored 35°C were given high scores for rancid. Despite the overall low scores for aroma and umami for samples stored at 35°C, the quality of the anchovy fish sauce as a fermented food was considered acceptable.

Effective Prevention of Oxidative Deterioration of Fish Oil: Focus on Flavor Deterioration

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), both abundant in fish oil, are known to have significant biochemical and physiological effects primarily linked to the improvement of human health, especially cardiovascular and brain health. However, the incorporation of fish oil into foods and beverages is often challenging, as fish oil is very easily oxidized and can cause undesirable flavors. This review discusses this rapid formation of the fishy and metallic off-flavors, focusing especially on an early stage of fish oil oxidation. Although oxidative stability and quality of commercialized fish oil have improved over the past few years, there is a still a problem with its application: Flavor deterioration can be found even at very low oxidation levels. This review also notes the effective way to inhibit the formation of the volatile compounds responsible for the flavor deterioration.