Influence of Phosphorylation and Acetylation on Structural, Physicochemical and Functional Properties of Chestnut Starch

Chestnut is popular worldwide for its unique flavor, high eating quality and nutrition. Here, we evaluated the influence of phosphorylation and acetylation on the structural, physicochemical and functional properties of chestnut starch. Scanning electron micrographs showed the agglomeration of starch granules and the appearance of numerous dents on the starch granule surface under phosphorylation and acetylation. X-ray diffractograms confirmed that the modification treatments did not affect the C-type crystal pattern, but reduced the relative crystallinity of the chestnut starch, particularly phosphorylation. Moreover, modification improved the paste transparency of the starch. Differential scanning calorimeter analysis revealed that the gelatinization temperature and enthalpy of the starch decreased with the increasing substitution degree, particularly in phosphorylated starch. The Rapid Visco Analyser analysis demonstrated that phosphorylation could greatly improve the pasting properties of chestnut starch. In addition, phosphorylated and acetylated starch had a smaller amount of slowly digested starch and a larger amount of resistant starch relative to native chestnut starch. In conclusion, the functional and physicochemical properties of chestnut starch can be significantly improved through phosphorylation and acetylation, demonstrating its great application potential as a food additive.

Inhibition of Bacterial Adhesion and Antibiofilm Activities of a Glycolipid Biosurfactant from Lactobacillus rhamnosus with Its Physicochemical and Functional Properties

Biosurfactants derived from different microbes are an alternative to chemical surfactants, which have broad applications in food, oil, biodegradation, cosmetic, agriculture, pesticide and medicine/pharmaceutical industries. This is due to their environmentally friendly, biocompatible, biodegradable, effectiveness to work under various environmental conditions and non-toxic nature. Lactic acid bacteria (LAB)-derived glycolipid biosurfactants can play a major role in preventing bacterial attachment, biofilm eradication and related infections in various clinical settings and industries. Hence, it is important to explore and identify the novel molecule/method for the treatment of biofilms of pathogenic bacteria. In the present study, a probiotic Lactobacillus rhamnosus (L. rhamnosus) strain was isolated from human breast milk. Firstly, its ability to produce biosurfactants, and its physicochemical and functional properties (critical micelle concentration (CMC), reduction in surface tension, emulsification index (% EI24), etc.) were evaluated. Secondly, inhibition of bacterial adhesion and biofilm eradication by cell-bound biosurfactants from L. rhamnosus was performed against various biofilm-forming pathogens (B. subtilis, P. aeruginosa, S. aureus and E. coli). Finally, bacterial cell damage, viability of cells within the biofilm, exopolysaccharide (EPS) production and identification of the structural analogues of the crude biosurfactant via gas chromatography–mass spectrometry (GC–MS) analysis were also evaluated. As a result, L. rhamnosus was found to produce 4.32 ± 0.19 g/L biosurfactant that displayed a CMC of 3.0 g/L and reduced the surface tension from 71.12 ± 0.73 mN/m to 41.76 ± 0.60 mN/m. L. rhamnosus cell-bound crude biosurfactant was found to be effective against all the tested bacterial pathogens. It displayed potent anti-adhesion and antibiofilm ability by inhibiting the bacterial attachment to surfaces, leading to the disruption of biofilm formation by altering the integrity and viability of bacterial cells within biofilms. Our results also confirm the ability of the L. rhamnosus cell-bound-derived biosurfactant to damage the architecture of the biofilm matrix, as a result of the reduced total EPS content. Our findings may be further explored as a green alternative/approach to chemically synthesized toxic antibiofilm agents for controlling bacterial adhesion and biofilm eradication.

Effect of Traditional Process Methods on the Physicochemical and Functional Properties of a Traditional Food Salt (Nikkih) Obtained from Waste Biomass Peels of Musa paradisiaca and Musa acuminate

In Cameroon, agrofood waste biomass such as peels of Musa paradisiaca and Musa acuminate is being valorized using various traditional processing methods to produce a traditional functional food salt, potash, locally called nikkih. Nikkih has been reported to have varying physicochemical and functional properties, which negatively affect the quality and stability of food prepared using it. This work aims at evaluating the effect of traditional process methods on the physicochemical and functional properties of nikkih produced from these peels in view of the optimization of the process. The peels were preprocessed using two methods: boiling at 90oC before drying and direct drying of raw samples. All samples were dried and combusted to ash at varying temperatures of 250oC, 300o C, and 350oC and times of 30 min, 60 min, and 90 min. The ash obtained was dissolved in varied volumes of water, filtered to obtain the nikkih. Yellow achu soup was prepared through the dry gum method using water and read palm oil, with nikkih as emulsifier. The physicochemical and functional properties of nikkih on yellow achu soup were evaluated using standard methods. The ash yield ranged from 10.62 ± 0.12% to 7.10 ± 0.05%, with the raw samples combusted at 3000C and 2500C having the highest and lowest values respectively. The pH of nikkih ranged from 10.95 ± 0 to 12.01 ± 0.056 while potash content ranged from 32.45 ± 0.905% to 72.29 ± 1.31%, with the highest and lowest values obtained from the raw sample combusted at 2500C and the boiled samples combusted at 3500C respectively. Alkaline content ranged from 61.7 ± 0.141% to 52.8 ± 0.141%, with boiled M. acuminate combusted at 3500C having the highest value and the lowest from raw M. paradisiaca combusted at 2500C. The foaming capacity and foam stability ranged from 6.9 ± 0.01% to 16.07 ± 2.51% and from 3.20 ± 0.07% to 11.205 ± 2.39% for M. acuminate and M. paradisiaca respectively. The emulsification index ranged from 85.62 ± 0.09% to 86.67 ± 1.141% after 24 hrs and from 26.0 ± 0.94% to 27.02 ± 2.390% after 48 hrs, with the highest value from the raw M. acuminate combusted at 350oC and the lowest from that combusted at 3000C. The potash source, pretreatment method, combustion conditions, and dilution factors all had an effect on the physicochemical and functional properties of nikkih.