Biogenic amines as an indicator of rye leaven quality during production and storage.

Rye leaven, the basic constituent of sour rye soup ('zurek' or white borsch), was obtained through three methods of initiating lacto-fermentation of rye flour. Optimal concentrations of NaCl (1.5%) and garlic (0.5%) were selected by utilizing the response surface methodology. During the production and storage of leaven at 10 °C and 20 °C, the secalin proteins of rye flour degraded significantly and the concentration of free amino acids increased, making the rye leaven an environment potentially conducive to the formation of biogenic amines. Putrescine (max. conc: 116.7 mg kg-1) and tyramine (max. conc: 63.4 mg kg-1) were the amines that occurred in the largest amounts in the leavens. The final concentration of histamine (after 150 days of storage) did not exceed 22 mg kg-1. Regardless of the method of initiation of fermentation, the products that contained fewer biogenic amines better retained their sensory characteristics (r ≤ -0.89, p < 0.05) and had a higher number of lactic acid bacteria (r ≤ -0.66, p < 0.05).

Chemical Safety and Quality Attributes of Dried Sausage Snacks Stored in Modified Atmosphere.

A sausage snack was produced by air blast drying of cottage sausage, and its safety and quality were investigated during 10-week storage period in a modified atmosphere (20% CO2/80% N2) at 4 ± 1°C and 20 ± 1°C. The results of a sensory and instrumental evaluation of colour and texture showed that significantly greater changes in these parameters were caused by drying the sausage rather than during subsequent storage of the produced snacks. Although total viable count increased and reached a maximum value of 6.5 log CFU g-1 after 70 days of storage at 20 ± 1°C, Enterobacteriaceae were not detected. The histamine level was approx. 18 mg kg-1, while the average content of the other biogenic amines after 70 days of storage ranged from 4.4 mg kg-1 (cadaverine) to 32.1 mg kg-1 (tyramine). The biogenic amine index was small and varied from 34.5 mg kg-1 (in the sausage before drying) to 73.4 mg kg-1 (at the end of the snack storage at 20 ± 1°C). The lipid hydrolysis and oxidation proceeded slowly and did not pose a threat to the product quality. The combination of drying and modified atmosphere packaging maintains good quality and safety of sausage snack during 70 days at refrigerated storage and/or 4 weeks at room temperature.

Effect of Alcalase Modification of Yellow Lupin (Lupinus luteus L.) Protein Isolate on Some Functional Properties and Antioxidant Activity.

Protein isolate obtained from sweet yellow lupin (Lupinus luteus L.) and its Alcalase hydrolysates were examined for their functional and antioxidant properties in relation to surface hydrophobicity of proteins and peptides and molecular weight distribution. Enzymatic hydrolysis improved the foaming characteristics of lupin proteins, while the emulsifying properties deteriorated. It means that good foaming properties of preparations are determined by the presence of low-molecular δ conglutin and small subunits of γ conglutins. In turn, larger proteins such as α and ß conglutin are responsible for maintaining good emulsifying properties. The measured surface hydrophobicity was consistent with the results of emulsifying properties. It has also been shown that the scope of changes in antioxidant properties due to hydrolysis, measured by DPPH method and as reducing power, is more pronounced than with the use of ABTS and FRAP methods.

Nucleotide degradation, biogenic amine level and microbial contamination as quality indicators of cold-stored rainbow trout (Oncorhynchus mykiss) gravad.

The extent to which the transformation of nucleotides, biogenic amines, and microbiological changes affect the quality and shelf life of vacuum packaged low processed rainbow trout (Oncorhynchus mykiss) gravad during storage at 7 ± 1 °C for 42 days was investigated. Although total viable counts increased slowly up to 6 log CFU g-1 at the end of storage, coliform bacteria disappeared. The histamine concentration and the biogenic amine index increased up to 45.2 ± 1.62 mg kg-1 and 100 mg kg-1 respectively. The highest concentration of inosine monophosphate was achieved in freshly prepared gravad, whereas the hypoxanthine level increased with storage time up to 28 days. Among nucleotide ratios, the G value is more suitable for the determination of gravad quality than K, Ki and H values. Once the gravad obtained the limit of acceptability by the panelists (35 days) the G value rose to 470%.

Impact of enrichment with egg constituents on water status in gluten-free rice pasta - nuclear magnetic resonance and thermogravimetric approach.

Effects of freeze-dried egg white, yolk and whole egg enrichment on water behaviour in fresh pasta dough, dried and cooked rice pasta with respect to control samples were studied by 1H nuclear magnetic resonance (NMR) relaxometry and thermogravimetric analysis. Enrichments caused lower mobility of water (T2) localised within the starch-protein matrix in fresh dough as well as dried pasta. Water compartmentalization was also downgraded in cooked products. Water fractions with different T2 values were linked to temperature peaks at the first derivative of the thermogravimetric (DTG) curve. From the DTG curve strong interaction of water molecules with proteins of egg white was revealed. Egg proteins also influenced viscoelastic properties of dough, and enhanced the firmness and chewiness of cooked pasta. Structural changes induced by various types of enrichment were reflected in the different molecular mobility at the water-matrix interface (T1). The enrichments also altered the colour and cooking properties.

Effects of onion or caraway on the formation of biogenic amines during sauerkraut fermentation and refrigerated storage.

The effects of onion or caraway on changes in the content of biogenic amines were examined in sauerkraut during a fermentation process at 18 °C or 31 °C for 14 days and subsequent storage at 4 °C for 12 weeks. The amines were analysed by high-performance liquid chromatography with pre-column benzoylation. Total biogenic-amine concentration at the end of the fermentation was lower at 31 °C than at 18 °C. However, at this lower temperature, the presence of caraway or onion more significantly (than at 31 °C) reduced the total biogenic-amine content as compared to the control sample without an additive. After 12 weeks of refrigerated storage, concentrations of phenethylamine, tryptamine, and tyramine in the sauerkraut fermented with caraway (and concentrations of putrescine and tryptamine in the sauerkraut fermented with onion) at 31 °C increased as compared to the samples on the last day of fermentation, but did not pose a risk for consumer health.

The impact of LED lighting on the yield, morphological structure and some bioactive components in alfalfa (Medicago sativa L.) sprouts.

The aim of this study was to evaluate the impact of selected types of LED (light emitting diodes) lighting on the quality of alfalfa sprouts. In the experiment, cold white, warm white and multicolour: (red, green, blue-RGB) LEDs were applied, and dispersed sunlight was used as a control. The product was examined for the yield and the contents of dry matter, total polyphenols, ascorbic acid, chlorophylls, ß-carotene, lutein, neoxanthin and violaxanthin. Cotyledons' mass in the whole plant increased under LED illumination and was up to 50% greater for sprouts grown in RGB light compared to those cultivated in dispersed sunlight. The highest chlorophyll and carotenoid pigment contents in cotyledons were observed under RGB LED and cold white treatments. Similarly, RGB LEDs allows one to obtain the product with the highest level of total phenolic compounds. The highest ascorbic acid content was observed in sprouts growing under sunlight, followed by RGB.

Autoproteolysis rate of rainbow trout muscle proteins.

Effect of some physicochemical agents (pH, temperature and incubation time) and iced storage of farmed rainbow trout (Oncorhynchus mykiss) on autoproteolysis of muscle proteins and quality (sensory assessment, instrumental texture, total bacterial counts) were determined. The results showed that the autoproteolysis rate proceeded with its highest intensity at pH 4.2 and temperature about 55 degrees C. The rate of protein hydrolysis and protease activity, as well as microbial contamination, gradually increased with prolonged periods of iced storage of fish. Properly iced trout immediately after its evisceration was acceptable in quality for up to 10 days.