Hydrogel properties of non-conventional starches from guabiju, pinhão, and uvaia seeds.

The physicochemical properties of starch vary depending on the botanical sources, thereby influencing the gelatinisation/retrogradation properties and subsequently affecting the hydrogels characteristics. This study aimed to assess the influence of botanical sources influence on starch and hydrogel properties using non-conventional starch derived from guabiju, pinhão, and uvaia seeds. Hydrogels were prepared by starch gelatinisation followed by 6 h ageing period at room temperature (20 ± 2 °C) and subjected to five freeze-thaw cycles. Pinhão starch exhibited a higher viscosity peak and breakdown, along with a lower final viscosity and setback, compared to guabiju and uvaia starches. The significantly different pasting properties influenced the porous microstructure, water absorption (p-value: 0.01), and resistance of the hydrogels (p-value: 0.01). The guabiju starch hydrogels showed a uniform pore structure without cavities, whereas pinhão and uvaia starch hydrogels exhibited agglomerated and spongy pore structures. Furthermore, the guabiju starch hydrogel demonstrated the lowest water absorption (4.56 g/g) and the highest compression resistance (1448.50 g) among all the studied starch hydrogels. In contrast, the pinhão starch hydrogel showed the highest water absorption (7.43 g/; p-value: 0.01) among all studied starch hydrogels. The hardness of uvaia starch hydrogel did not differ significantly from the guabiju and pinhão starch hydrogel. The different non-conventional starches reveal important variations in the hydrogels characteristics. This provides insights into how amylose and amylopectin interact and present alternatives for using these unique starch-based hydrogels in diverse applications.

Antilisterial activity of cinnamon essential oil, pomegranate extract, or strawberry tree extract against Listeria monocytogenes in slices of dry-cured ham and pork loin.

Owing to concerns about the antimicrobial resistance of agents that can prevent the growth of Listeria monocytogenes in meat, researchers have investigated natural preservatives with antilisterial effects. However, in vivo application of essential oils and plant extracts usually results in reduced antimicrobial activity in meat products when compared to in vitro studies. This study aimed to evaluate the in vivo antimicrobial activity of cinnamon essential oil, pomegranate, and strawberry tree extracts in slices of dry-cured ham and pork loin against L. monocytogenes. Fragments of sterile dry-cured ham were inoculated with 100 µL cinnamon oil 0.5%, pomegranate, or strawberry crude extract. After 10 min, 100 µL of L. monocytogenes serotype 4b (104 colony-forming unit [CFU]/mL) was inoculated, and samples were incubated at 7 °C for 7 d to simulate the processing and storage temperature conditions of dry-cured meat products. L. monocytogenes was detected and quantified. Only strawberry extract presented significant differences (P < 0.05) from the control; thus, it was selected for the assay with 2% and 4% salt-treated pork loin. The strawberry tree extract significantly (P < 0.05) reduced the growth of L. monocytogenes in dry-cured ham. However, it could not reduce L. monocytogenes growth in pork loin, regardless of the salt concentration. This is the first report on the antimicrobial effect of strawberry tree leaf extract against L. monocytogenes in dry-cured ham.

Listeria monocytogenes: health risk and a challenge for food processing establishments.

Listeria monocytogenes is a pathogenic bacterium present in several environments able to survive and proliferate in food processing plants, contaminating products that when ingested can lead to listeriosis. Worldwide, the bacterium has been isolated from foods of animal and plant origin and its occurrence in ready-to-eat foods is a challenge for food processing establishments. Serotypes 1/2a, 1/2b, 1/2c, and 4b related to 95% of listeriosis cases have been detected in different foods and presented resistance to common antibiotics such as tetracycline and penicillin. The analysis and dissemination of the presence of L. monocytogenes in different foods are essential to anchor control and prevention measures. In Brazil, despite the lack of official data on contamination by L. monocytogenes, some studies have reported the presence of bacteria in various foods and food processing environments. Thus, this review focuses on presenting the main characteristics of the L. monocytogenes, resistance to antimicrobial agents, and occurrence in several foods and countries from 2010 to 2020.