Effect of probiotic lactobacilli on faecal enzyme and genotoxic activity in human faecal water in the presence of the carcinogen PhIP in vitro

The average β‐glucuronidase activity for children was 0.48 ± 0.04 U/mg, for adults 0.75 ± 0.27 U/mg and for elderly 1.55 ± 0.06 U/mg. For β‐glucosidase, it was 0.19 ± 0.02 U/mg for children, 0.77 ± 0.26 U/mg for adults and 1.18 ± 0.27 U/mg for elderly. In the presence of probiotics, the highest decrease in genotoxicity was observed for Lactobacillus casei 0908 (to 7.99 ± 1.32) and Lactobacillus paracasei 0919 (to 6.19 ± 1.44) for all children. In adults, lower mean genotoxicity was regarded after incubation of PhIP with L. casei 0908 (it was 5.27 ± 1.13) and L. paracasei 0919 (it was o 6.01 ± 1.00). For elderly, statistically significant decrease was maintained after incubation of PhIP with L. casei 0900 (to 6.72 ± 2.67).     

CRISPNESS AND CRUNCHINESS JUDGMENT OF APPLES BASED ON CONTACT ACOUSTIC EMISSION

Contact acoustic emission (AE) measurement, together with a puncture test, were used to evaluate the crispness and crunchiness of three apple cultivars. A storage program was used to induce changes in apple crispness and crunchiness. The instrumental measurements were compared with the results of sensory evaluation.
It was found that crispness and crunchiness could be evaluated instrumentally by measuring firmness, AE events, mean AE amplitude or the product of AE events and mean AE amplitude. For one cultivar, however, firmness was not correlated with any sensory attribute. Generally, the best correlation with sensory attributes was found for the exponential value of AE events. Contact AE allows the measurement of sensory crispness or crunchiness for a given apple cultivar or independently for any apple cultivar. Contact AE can be considered as a useful method for the evaluation of sound properties of wet-crisp foods.

PRACTICAL APPLICATIONS

Contact acoustic emission method can be used for instrumental evaluation of crispness and crunchiness of apples. The method allows more accurate evaluation of these attributes than firmness measurement. There is a chance to extend the application to other wet-crisp foods and to use the method together with other destructive tests, like texture profile analysis or single edge notched bend.     

INFLUENCE OF NONENZYMATIC GLYCOSYLATION (GLYCATION) OF PEA PROTEINS (PISUM SATIVUM) ON THEIR SUSCEPTIBILITY TO ENZYMATIC HYDROLYSIS

The Maillard reaction, also referred to as nonenzymatically glycosylation (glycation), causes changes to protein structure and occurs in food. The aim of this study was to investigate changes in susceptibility of glycated pea proteins to enzymatic hydrolysis. A pea proteins extract was glycated using different sugars (glucose, fructose, lactose and glucosamine). Then, the physicochemical changes of proteins after glycation in ultraviolet spectra as well as the content of sugars and free amino groups were determined and also separated electrophoretically. Native and glycated pea proteins were hydrolyzed for 120 min with pepsin (one-step hydrolysis) or with pepsin and trypsin (in two-step process). Pea proteins glycated by glucose and lactose were less susceptible to pepsin hydrolysis than the pea proteins glycated by fructose and glucosamine in comparison with native pea proteins. Glycated pea proteins were more susceptible to hydrolysis by pepsin and trypsin in the two-step hydrolysis than the native ones.

PRACTICAL APPLICATION

Nonenzymatic glycosylation (glycation) of food proteins is used for the improvement of their functional properties. The formed glycoproteins can be characterized by changing biochemical properties, i.e., the susceptibility to the enzymatic hydrolysis or the influence on the growth and survival of the gut microflora. For this reason, investigations on the effect of the glycation of food proteins on their biological properties were necessary from the nutritional and health-promoting point of view.     

THE EFFECT OF PRETREATMENT OF SHREDDED CELERIAC USING SOLUTIONS OF ENZYMATIC BROWNING INHIBITORS ON THE QUALITY OF MINIMALLY PROCESSED PRODUCT

ABSTRACT

The study investigated the effect of soaking celeriac flakes in solutions containing various concentrations of enzymatic browning inhibitors on the quality of stored minimally processed product. Ascorbic acid (0.2–0.5%), 4‐hexylresorcinol (0.003–0.01%), sodium chloride (0.1–0.5%) and sodium lactate (2–3%) were used as browning inhibitors. On the basis of the conducted tests, it was found that among the applied browning inhibitors, only ascorbic acid had an advantageous effect on the quality of stored celeriac flakes. Along with an increase in its concentration in the solution (0.2–0.5%) used for the pretreatment of the flakes, the value of color parameter a* decreased, while the value of parameter b* increased. At the concentration of ascorbic acid in the solution exceeding 0.25%, flake color in the sensory examination was evaluated as desirable. An increase of ascorbic acid concentration in the solution in the range from 0.2 to 0.4% resulted in a decrease in the total mesophilic and psychrophilic bacteria counts, respectively, by 3 and 1 log cfu/g of the stored product.

PRACTICAL APPLICATIONS

Minimal processing of celeriac provides convenience for consumers and many economic benefits for producers. Minimal processing of celeriac can induce disadvantageous changes in tissue, which may lead to darkening of the flakes and deterioration of product sensory attributes. Moreover, shredded raw material constitutes an excellent medium for the development of microorganisms. This article contains information about the effectiveness of enzymatic browning inhibitors for extending the shelf life of celeriac flakes. We show a range of concentrations of inhibitors, which improve the preservation of color, intrinsic taste and microbial quality of minimally processed celeriac.