The recent development of coffee industry is largely driven by consumers’ interests in more sophisticated and complex coffee flavors. Coffee products with novel and desirable sensory attributes can attract substantial interest from the market. The traditional method of coffee cherry on-farm process lacks controllability and consistency in flavour development, therefore a more controllable and targeted biotransformation technique is warranted.
Our technology involves the application of innovative biotreatment on sterilised green coffee beans with selected strains of lactic acid bacteria and yeasts, followed by the proper roasting of fermented green coffee beans. The treated coffee beans exhibit novel aromas which combines the essence of coffee and fruity wine, without alcohol content in it. The naturally generated fruity and wine-like aroma in the treated coffee is strong enough to be easily detected by consumers. Furthermore, it elevates the acidity of the resulted coffee, which is an attribute of a high-quality coffee. The final roasted coffee can be utilized in the preparation of specialty coffees, coffee beverages, coffee flavouring, and other coffee-related products.
Besides the positive flavour modification, our technology also has the advantage in being more environmentally friendly by reducing water usage, as compared to the traditional wet on-farm processing of coffee cherries. The process is controllable and suitable for industrial production. In particular, the process is suitable for low-end green coffee beans to improve their quality.
This invention involves fermentation of sterilized green coffee beans using defined microorganisms with or without sugar supplementation, followed by roasting the treated green coffee beans.
The “green coffee beans” refers to the raw coffee seeds that have been produced with on-farm processing in which the coffee seeds are released from rest of the coffee cherries. Dried and un-dried green coffee beans from various coffee varieties and different on-farm processing are all suitable for this invention. It should be noted that the use of dried green coffee beans facilitates transportation and storage.
The potential fermentation microorganisms are not restricted to the endogenous microbiota on coffee matrix but include vast variations of fermentation microorganisms that are commercially available and used in the processing of other foods. The microorganisms used in the invention include the dairy lactic acid bacteria Lactococcus lactis subsp.cremoris ATCC 19257, the wine yeasts Saccharomyces cerevisiae Merit.ferm and Pichia kluyveri FrootZen. The selection of microbial stains is based on their abilities to survive and metabolize in the green coffee fermentation matrix, to modify the flavour-related constituents in the green coffee beans, and to positively modify the final roasted coffee flavour. With proper selection and combination of fermentation microorganisms, targeted modulation and improvement of coffee sensory attributes can be achieved.
The treated green or roasted coffee beans can be supplied to food and beverage companies and flavouring companies, or specialty coffee shops. Potential applications of the specialty coffee (raw and roasted) from the invention:
In recent years, we witnessed the “third wave of coffee” that emphasizes on the careful preparation of high-quality coffee beans to make beverages with premium sensory characteristics. The recent development of coffee industry is largely driven by consumers’ interests in more sophisticated, complex and novel flavours of their coffees. Our invention involves production of green coffee beans with enhanced aromatic potential, the final roasted coffees exhibit unique and pleasant sensory characteristics, which distinguishes it from the rest of the coffee products.
Traditionally, green coffee beans are processed by “on-farm processing”, during which the coffee seeds are released from the rest of coffee cherries using different methods in the coffee farm shortly after the cherry harvest. The resulted coffee seeds are termed as “green coffee beans”. If conducted properly, the spontaneous microbial fermentation that takes place during traditional on-farm processing can positively modulate the flavour-related constituents in green coffee beans and characterizes the final product with preferable/desirable flavour. However, such uncontrolled process suffers from lack of controllability, low consistency, large water consumption, together with high weather- and location-dependency. Thus, there is a strong need in the industry for a controllable, eco-friendly, and economic bio-transformation technique for green coffee bean processing. Our invention meets this demand with an innovative post-harvest process technique in which fully controlled microbial fermentations are applied directly on on-farm processed green coffee beans, particular those dry- or semi-dry processed ones with limit aroma potential and low market value.