Ferulic acid pretreatment alleviates the decrease in hardness of cooked Chinese radish (Raphanus sativus L. var. longipinnatus Bailey)

Sodium bicarbonate reduces the cooked hardness of lotus rhizome via side chain rearrangement and pectin degradation

In this study, 0.1% (W/V) sodium bicarbonate (SB) solution was used to soften lotus rhizome, and the mechanism was characterized by monoclonal antibodies labeling (mAbs) and atomic force microscopy (AFM). The results showed that the cell wall of lotus rhizome was disintegrated under SB treatment. In addition, the mAbs results revealed that low-esterified homogalacturonan (HG) at the tricellular junction was degraded, the rearrangement of Ara and the interaction between Gal and cellulose may be related to the texture changes. Compared with distilled water treatment, SB treatment reduced the relative content of pectin from 34.1% to 19.1% while increased that of cellulose from 65.9% to 80.9%. AFM results revealed that the height of CSF skeleton decreased from about 32 nm to 1.5 nm. These results clearly demonstrate that cooking with 0.1% SB can soften lotus rhizome through degradation of pectin and arrangement of side chains of rhamnogalacturonan-Ⅰ (RG-Ⅰ).

Comparative evaluation of package types in alleviating textural softening and package-swelling of Paocai during storage: Insight into microbial invasion, cell wall pectinolysis and alteration in sugar and organic acid profiles

The present study aimed to investigate the effect of initial vacuum package (VP), air package (AP) and salt-solution package (NP) on texture softening and package-swelling of Paocai by comparing the changes in physicochemical properties, pectinolysis, microstructure, microbial profile, as well as sugar and organic acid profiles during storage. Results showed that, when compared with AP and NP, with suppressive microbial invasion and less total pectinase activity, VP could retain more soluble pectin and induce more compact microstructure of Paocai, leading to higher hardness of Paocai during storage. As for package-swelling, VP mitigated gas-production in package by changing the microbial composition and metabolic patterns of sugar and organic acid in Paocai, especially targeted regulating the abundance of genus Kazachstania. This study provided a perspective for appropriate packaging technology to control the pectinase activity as well as cell-invading and gas-producing microorganisms for manufacturing fermented vegetable with better texture and non-package-swelling.

Development of a Novel Electrochemical Biosensor Based on Carbon Nanofibers-Gold Nanoparticles-Tyrosinase for the Detection of Ferulic Acid in Cosmetics

The present paper deals with the electrochemical behavior of three types of sensors based on modified screen-printed electrodes (SPEs): a sensor based on carbon nanofibers (CNF/SPE), a sensor based on nanofibers of carbon modified with gold nanoparticles (CNF-GNP/SPE) and a biosensor based on nanofibers of carbon modified with gold nanoparticles and tyrosinase (CNF-GNP-Ty/SPE). To prepare the biosensor, the tyrosinase (Ty) was immobilized on the surface of the electrode already modified with carbon nanofibers and gold nanoparticles, by the drop-and-dry technique. The electrochemical properties of the three electrodes were studied by cyclic voltammetry in electroactive solutions, and the position and shape of the active redox peaks are according to the nature of the materials modifying the electrodes. In the case of ferulic acid, a series of characteristic peaks were observed, the processes being more intense for the biosensor, with the higher sensitivity and selectivity being due to the immobilization of tyrosinase, a specific enzyme for phenolic compounds. The calibration curve was subsequently created using CNF-GNP-Ty/SPE in ferulic acid solutions of various concentrations in the range 0.1-129.6 μM. This new biosensor allowed low values of the detection threshold and quantification limit, 2.89 × 10-9 mol·L-1 and 9.64 × 10-9 mol·L-1, respectively, which shows that the electroanalytical method is feasible for quantifying ferulic acid in real samples. The ferulic acid was quantitatively determined in three cosmetic products by means of the CNF-GNP-Ty/SPE biosensor. The results obtained were validated by means of the spectrometric method in the infrared range, the differences between the values of the ferulic acid concentrations obtained by the two methods being under 5%.

Interactions between cell wall polysaccharides and polyphenols: Effect of molecular internal structure

Cell wall polysaccharides (CPSs) and polyphenols are major constituents of the dietary fiber complex in plant-based foods. Their digestion (by gut microbiota) and bioefficacy depend not only on their structure and quantity, but also on their intermolecular interactions. The composition and structure of these compounds vary with their dietary source (i.e., fruit or vegetable of origin) and can be further modified by food processing. Various components and structures of CPSs and polyphenols have been observed to demonstrate common and characteristic behaviors during interactions. However, at a fundamental level, the mechanisms that ultimately drive these interactions are still not fully understood. This review summarizes the current state of knowledge on the internal factors that influence CPS-polyphenol interactions, describes the different ways in which these interactions can be mediated by molecular composition or structure, and introduces the main methods for the analysis of these interactions, as well as the mechanisms involved. Furthermore, a comprehensive overview is provided of recent key findings in the area of CPS-polyphenol interactions. It is becoming clear that these interactions are shaped by a multitude of factors, the most important of which are the physicochemical properties of the partners: their morphology (surface area and porosity/pore shape), chemical composition (sugar ratio, solubility, and non-sugar components), and molecular architecture (molecular weight, degree of esterification, functional groups, and conformation). An improved understanding of the molecular mechanisms that drive interactions between CPSs and polyphenols may allow us to better establish a bridge between food processing and the bioavailability of colonic fermentation products from CPSs and antioxidant polyphenols, which could ultimately lead to the development of new guidelines for the design of healthier and more nutritious foods.

Acetic acid reducing the softening of lotus rhizome during heating by regulating the chelate-soluble polysaccharides

Lotus rhizomes were used to study on the relationship between the cell wall polysaccharides and cooked texture by adding acetic acid. Hardness and scanning electron microscopy results showed that acetic acid treatment can maintain higher hardness and the integrity of the cell wall. Then, the cell walls were sequentially extracted and divided into water-soluble fraction, chelate-soluble fraction (CSF), sodium carbonate-soluble fraction and hemicellulose fraction. The pectin fraction contents, monosaccharides composition, esterification degree and sugar ratios in different groups were evaluated, the results showed that acetic acid increased the total amount of CSF, decreased the esterification degree and less side chain compared that in the solely thermal treatment group. The nanostructures showed that acetic acid treatment maintained longer chain and destroy helical structure of CSF backbone. This work helps us to demonstrate the relationship between polysaccharides structure and cooked texture, and further control the plant-based vegetables processing texture in food industry.