Characteristics and properties of the quaternary ammonium-functionalized micron chitosan modified by zinc citrate chelates for encapsulation of betanin

Betanin is a high-value bioactive ingredient, but its application in the food industry is limited by its easy degradability. Encapsulation can improve the stability of various ingredients and is widely used in the food industry. In this work, chitosan modified by zinc citrate chelates (CS@Zn-CQDs) were synthesized by one-pot synthesis and the surface of them was quaternary ammonium-modified to get quaternary ammonium-functionalized micron chitosan modified by zinc citrate chelates (MQACS@Zn-CQDs). The loading capacity of MQACS@Zn-CQDs was 58.79%, which is higher than that of chitosan (CS, 0.72%), CS@Zn-CQDs (3.5%) and quaternary-ammonium functionalized CS@Zn-CQDs (QACS@Zn-CQDs, 50.47%). Encapsulation can keep the antioxidation ability of betalaines under high-temperature and alkaline (pH=10) environment, and the retained antioxidant activity of encapsulated betalaines is significantly higher than that of un-encapsulated betalaines. The cell viability was over 90% in betanin, CS, and betanin-MQACS@Zn-CQDs, showing that they have ideal food safety. CS, CS@Zn-CQDs, and MQACS@Zn-CQDs have good betanin delivery ability, and above 75% of betanin release was occurred in the intestine. MQACS@Zn-CQDs showed bacteriostatic activity against the spoilage bacteria derived from baked bread. In summary, MQACS@Zn-CQDs can be regarded as a promising novel carrier for the encapsulation of betanin or other hydrophilic nutraceuticals, and they have the potential of use in baked bread to inhibit spoilage bacteria.

Automated summary

In this study, a modified chitosan was synthesized to serve as a carrier for encapsulating hydrophilic nutraceuticals such as betanin. The modified chitosan exhibited good encapsulation ability, antioxidant activity, and antibacterial properties, making it a promising option for inhibiting spoilage bacteria in food.