Upcycling of coffee pulp and mucilage (coffea arabica) in human foods

Abstract

Pulp and mucilage comprise potential contaminants in wet coffee processing. Nevertheless, these co-products represent a high nutritional value with low caloric level. The objective of this study was to evaluate the potential use of coffee pulp and mucilage as ingredients in the baking industry substituting ingredients like wheat flour (HT) and honey, respectively. Randomized complete block designs (RCBD) were implemented, analyzed through and ANOVA with Duncan mean´s separation and a probability lower than 5% (p ≤.05). First, the effects of coffee pulp on the physicochemical, sensory and nutritional characteristics of brownies were evaluated. Proximal analysis was conducted on the coffee pulp flour (HPC) from the Catuai and Lempira varieties. Brownies were developed with four formulations including a control and partial substitutions of WF with 30, 40 y 50% HPC (Phase I). Subsequently, the 50% HPC formulation was chosen as a control to develop three formulations with reduction in caloric intake from fat, sugar and both for the second phase of the study. Sensory, texture, and color analyses were evaluated in brownies in both phases. A protein and dietary fiber analysis was performed comparing the control brownie (100% HT) and the low-calorie brownie (50% HPC and reduced sugar). Humidity (6.23%), carbohydrates (48.55%), protein (8.84%), fat (2.60%), ash (7.61%), and crude fiber (25.86%) were evaluated in HPC with a caloric contribution of 391.95 Kcal/100 g. As HPC content was increased, better acceptance, more rigid consistency and darker color were observed in brownies. Brownies with a reduction of fat and sugar had good acceptance despite the decrease of calorie intake and differences in physical parameters. The 50% HPC brownie with reduced sugar resulted in high fiber content, making this co-product a potential ingredient to reduce the use of conventional flours. In parallel, the use of concentrated coffee mucilage (MCC) as a substitute for honey was evaluated in cookies. Three cookie treatments were developed with substituions (0, 50, 75%) of honey by MCC. The effect of these substitutions were evaluated in cookie color, calories, texture and sensory attributes of acceptance. The treatment with 50% MCC substitution resulted in better texture in cookies showing similar results in consumer acceptance compared to the honey sweetened cookies (control). It was concluded that the MCC did generate physicochemical changes in product formulation, but a partial substitution of sweeteners such as honey and sugar could be achieved. In general, uses and applications were demonstrated  for co-products that are currently discarded or used as organic fertilizers on coffee farms. Alternatives for revaluing these materials should continue to be evaluated and their reintroduction into human food as a priority.