Active coatings of thermoplastic starch and chitosan with alpha-tocopherol/bentonite for special green coffee beans

• Published in: International journal of biological macromolecules 2021-02, Vol.170, p.810-819
• Main Authors: Ferreira, Laura Fonseca, Figueiredo, Luísa Pereira, Martins, Maria Alice, Luvizaro, Lucas Baldo, bLara, Bruna Rage Baldone de, Oliveira, Cassiano Rodrigues de, Júnior, Mário Guimarães, Tonoli, Gustavo H.D., Dias, Marali Vilela
• Format: Article
• Language: English
• Subjects: alpha-Tocopherol - chemistry; Antioxidant activity; Antioxidants - chemistry; Bentonite - chemistry; Cavitation energy; Chitosan - chemistry; Coffee - chemistry; Food Preservation - methods; Starch - chemistry; Steam; Ultrasonic probe; WVP; XRD
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2020.12.199

The quality of green coffee beans (GCBs) is possibly affected by storage conditions. Edible polymer coatings for GCBs can help preserve flavors and improve shelf life of GCBs. This study aimed to incorporate α-tocopherol, a powerful antioxidant, in thermoplastic starch [TPS] and chitosan [TPC] and determined the best cavitation energy (960–3840 J·mL−1) using an ultrasonic probe. Then, we evaluated the incorporation of bentonite (0% and 2% m/m) and α-tocopherol (0% and 10% m/m) in the best energy cavitation/biopolymer combination. The TPS and TPC coatings demonstrated good adherence to the GCBs, measured by surface energy. The dispersion of α-tocopherol in TPC, with cavitation energy 960 J·mL−1, promoted greater stability (greater zeta potential), thereby increasing antioxidant activity by 28% compared to TPS, therefore, was selected for a second stage. Incorporation of 2% bentonite into the TPC, with 10% α-tocopherol, resulted in a 3.7 × 10−10 g·m−1·s−1·Pa−1 water vapor permeability, which is satisfactory for prevented of moisture gain during storage. The compressive load showed values of 375 N to the non-coated GCB and around 475 N with the insertion of coatings to the GCB. Thus, a TPC/α-tocopherol/bentonite combination, dispersed with 960 J·mL−1 energy, was highly effective in the development of biopolymeric coatings for the GCBs. •Green coffee bean coatings were developed and characterized.•The treatments presented satisfactory WVP.•The coatings could protect green coffee beans from compression.•In the roast the coatings will possibly melt and break free from the roasted coffee beans.