Development of an edible coating containing Plectranthus amboinicus powder for frozen dough products

Plectranthus amboinicus is a plant widely used in folk medicine, with its bioactive properties, attributed to thymol and carvacrol, well-documented in the literature. Innovation and the development of new food products have spurred research into the use of plant fractions for coatings in the bakery sector. The United Nations has set forth 17 Sustainable Development Goals (SDGs); the food industry can contribute to several of these, with innovative research directly supporting SDGs 2, 3, 9, 11, and 12. This study aimed to develop coatings enriched with Plectranthus amboinicus powder and to analyze the effects of freezing on the doughs treated with these coatings over a 60-day period. The coating was developed using modified starch, based on a central composite rotatable design (CCRD) consisting of 11 experimental runs. The coating formulation involved dissolving the modified starch in water, heating the mixture to 80°C, and adding 20.2% (v/v) glycerol. The best coating formulations were trial 4, containing 2% ascorbic acid and 7.5% malvarisco, and trial 8, containing 2.2% ascorbic acid and 6.25% malvarisco. The breads were prepared using a basic formulation; after being shaped into balls, they were submerged in the coating for 3 minutes, with the excess allowed to drain for 1 minute. Every 15 days, the breads were thawed and subjected to various analyses: evaluation of the fermentation process, specific volume, density, expansion index, dough volume generated during fermentation, and crumb structure analysis. An analysis of the results revealed that the technological quality of the doughs declined over the course of the freezing period; however, the coating helped mitigate the damage observed in breads that did not receive any treatment. The circularity of the air cells (alveoli) shifted from initial values ​​at time zero (0.948^aB±0.01) for P4 and (0.981^aA±0.01) for P8 to (0.873^eB±0.01) for P4 and (0.898^dA±0.01) for P8 after 60 days of freezing. It was observed that both the number of air cells formed and their circularity were higher in sample P8 than in sample P4. This is because sample P4 contains a higher proportion of malvarisco, which negatively affects physical properties by damaging the gluten network. Overall, the reduction in the number of air cells was 34.38% for sample P8 and 35.05% for sample P4. Consequently, the P8 coating demonstrated superior physical properties compared to P4. It was concluded that it is possible to develop various edible coatings for use in the baking industry, and that formulations with a lower content of malvarisco yielded better results over a 60-day freezing period.