The objective of the study was to analyse cellular structure of selected cereal products and its effect on acoustic emission generated during their breaking. Analyses were carried out for biscuits “A” and “B” and crackers. The structure of those products was determined by means of an electron scanning microscope FEI QUANTA 200 at 20x magnification, which enabled carrying out analyses in the natural form of products examined without their preliminary preparation. The cakes were subjected to a fracture test with a velocity of 50 mm/min in a testing machine coupled with an accelerometer registering acoustic emission (AE) in a frequency range of 0–15 kHz. Parameters of cellular structure were found to depend on the type of product. The structure of the material affected the acoustic emission generated during its breaking. Materials with smaller air pores generated sounds with a weaker acoustic energy. Large cellular spaces of the products caused a higher share of low-frequency sounds in the acoustic emission.
This paper documents the growth of Listeria monocytogenes, Enterococcus spp., coli and Escherichia coli bacteria in tvorog packaged under vacuum, CO₂ atmosphere, with the use of oxygen absorbers, and tvorog packaged under ambient atmosphere and cold stored at 5°C for 7, 14 and 21 days. The study indicates that the investigated packaging methods do not affect the growth of Listeria monocytogenes and Enterococcus spp in tvorog. The inhibited growth of the above bacteria during cold storage of tvorog was more related to the presence of acidifying bacteria and the product’s high acidity. Tvorog contamination with coli and Escherichia coli bacteria was very low. After 7 days, the above bacteria were detected only in tvorog samples packaged under ambient atmosphere.
Porównano sygnał emisji akustycznej (EA) generowany podczas trójpunktowego łamania ciastek, rejestrowanego dwoma różnymi sensorami. Badania przeprowadzono na krakersach, herbatnikach „A" i „В" o różnej aktywności wody. Sygnał emisji akustycznej (EA) generowany podczas łamania ciastek z prędkością 50 mm/min rejestrowano sensorami drgań o zakresie częstotliwości 0-15 kHz i 0-30 kHz. Rodzaj sensora użytego do pomiaru emisji akustycznej znacząco wpływa na amplitudę i częstotliwości generowanego sygnału EA. Czułość sensora oraz jego zakres pomiarowy są podstawowymi wyznacznikami w analizie zarejestrowanej energii akustycznej.