Source: UNIVERSITY OF FLORIDA submitted to
QUALITY ENHANCEMENT OF COFFEE BEANS BY ACID AND ENZYME TREATMENT
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0208321
Grant No.
2006-34135-17614
Project No.
FLA-FOS-04566
Proposal No.
2006-04350
Multistate No.
(N/A)
Program Code
AH
Project Start Date
Sep 15, 2006
Project End Date
Aug 31, 2009
Grant Year
2013
Project Director
Marshall, M. R.
Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
FOOD SCIENCE & HUMAN NUTRITION
Non Technical Summary
The worlds most expensive, and best quality coffee is Kopi Luwak, made from beans that are digested by the animal Luwak. Chnages occur to the beans due to stomach acids, enzymes, and fermentation in its digestive track. A method that would eliminate the necessity of the Luwak, and would reproducibly result in superior quality beans would add value to lesser quality coffee, and improve the economic situation of farmers, while supplying good coffee at a reaonable price to consumers. Our purpose is to find the optimal treatment conditions of coffee beans with acids, enzymes, and fermentation to emulate the conditions in the digestive track of the Luwak. Objective and taste panel evaluations of quality will be performed.
Animal Health Component
65%
Research Effort Categories
Basic
35%
Applied
65%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
5012232202060%
5022232200040%
Goals / Objectives
1.To develop a treatment method to enhance the quality of the coffee prepared from coffee beans produced in the Caribbean. This will involve a digestion process including acid and enzyme treatment of the beans. 2.To quantify the value added to the coffee beans by taste tests, and by scientific demonstration of the changes that occur as a result of the treatments. 3.To optimize the newly developed method for scalable commercial applications based on economics of raw materials and processing requirements.
Project Methods
Approach 1. To conduct chemical and physical analyses to determine the differencesbetween regular and digested coffee beans. a.Kopi Luwak beans, and regular beans from the same region will be obtained. b.Chemical analyses will be performed. These include proximate analysis (Kjeldahl for proteins, Soxhlet for lipids, ashing, moisture determination, carbohydrates by difference), protein profile by the SDS and natural gel electrophoresis and by capillary electrophoresis, electron micrographs of the surface of the beans, and aroma profile by Gas Chromatography (GC), olfactory port, and/or GC/MS or HPLC. c.Physical properties such as pH, titratable acidity, color, viscosity, and turbidity of the coffee drink will be measured. d.Microbial properties of the beans will be determined: total plate count, yeast/mold count, coliform/E.coli: 3-M petrifilm will be used. As a result, we will understand the chemical and physical differences existing between regular and Luwak processed coffee beans. Approach 2. To establish a baseline of quality using Kopi Luwak coffee by sensory tests. a.Trained sensory panel for descriptive organoleptic evaluation b.Consumer panel for preference tests As a result, we will understand the sensory characteristics of the gold standard to which all other samples will be compared. Approach 3. Preliminary experiments to determine the selection of processing parameters such as pH, enzymes to be used, temperature, time of exposure, and post-treatment processing conditions. The following will be the independent variables that affect the quality of the resulting beans and therefore the coffee drink: a.The mix of enzymes, b.The environment (pH, temperature) c.The sequence and exposure time of the beans to the different enzymes d.The inoculation with fermentation bacteria (lactic acid bacteria) e.The time of exposure to fermentation, f.Fermentation conditions (pH, temperature) After each process, coffee will be evaluated by sensory panel for the affirmation or rejection of the step towards the objective. As a result, we will understand and select the important process parameters having an impact on the final quality. Approach 4. To develop an experimental design to optimize the process conditions for quality enhancement effectiveness and cost saving. a.Response Surface Methodology will be adopted to develop an efficient experimental design to vary the independent variables selected in the previous step (at least 3 levels) b.Coffee drink taste testing will be the determining criterion for optimization of the process variables. As a result we will determine the optimum process conditions that result in the best quality product confirmed by taste tests. Approach 5. To quantify the quality enhancement of the resulting coffee drinks by chemical and physical tests. a.After optimum conditions are found, the chemical and physical attributes of the resulting coffee beans will be measured. b.This will allow further development of easy-to-use tests for quality control and assurance during the commercial operations. c.All tests mentioned in Approach 1 will be used.

Progress 09/15/06 to 08/31/09

Outputs
OUTPUTS: A method was developed to improve the quality attributes of raw coffee beans by treating them with acid and enzymes. All samples were analyzed by sensory tests, and electron microscopy for changes caused by treatments. An electronic nose was used to sniff the headspace of samples. A machine vision system, a non-destructive method to evaluate colors on non-uniform surfaces, was used to measure color of green and roasted beans before and after treatment. A roaster that can precisely control the heating profile during roasting was purchased and will be used to study color in coffee. Experiments were conducted to roast green coffee beans over time. Samples were taken at various times through roasting and color of the beans was assessed using a Machine Vision system. Color of coffee beans changed from green (L*=46.62, a*=3.75, b*=6.94) to dark brown (L*=13.65, a*=8.53, b*=-4.62) during the roasting. Two consecutive stages of color changes were observed: (i) drying and degradation of green pigments, mainly chlorophyll, with a significant increase (a=0.05) in L-value and (ii) melanoidin formation via Maillard reaction and Strecker degradation. Color of coffee extracts changed from light green (L*=48.09, a*=-3.23, b*=12.71) to dark brown (L*=14.84, a*=18.36, b*=23.98). No significant differences (a=0.05) were observed in L-value of extracts during the first 6 min of roast but a steep decrease in L-values was detected at 8 min. Changes in L*, a*, and b* values were used to develop a kinetic model of color during roasting. Total phenolics were analyzed during roasting and antioxidant capacity determined. Total phenolics reached maximum concentration at 189C, probably due to phenolic compounds via Maillard reaction but then decreased to the lowest level by the end of roasting (alpha=0.05). This is associated with degradation of the same phenolic compounds in the final stage of roasting where temperatures reach more than 200C. Free radical scavenging activity was highest at 166C and decreased to its lowest level at 209C (alpha=0.05). Antioxidant capacity of roasted coffee was significantly (alpha=0.05) higher when compared to green coffee. Trigonelline, caffeine and chlorogenic acids are present in coffee and have been associated with its antioxidant capacity. Although chlorogenic acid decreases in concentration during roasting, one possible explanation for the increase in the overall antioxidant activity might be the incorporation of fragments of these decomposed compounds in the melanoidin structure. This research targets the coffee industry. The enhancement of flavor and reduction of bitterness after treatment can be a competitive advantage, and an economic boost to the industry. This work has been submitted to Annual Meetings of the Institute of Food Technologists. This work will support the degrees for one Masters student and one PHD student. Ipanema Coffees from Brazil is acknowledged for contributing the coffee used in this study. This research targets the coffee industry. The enhancement of flavor and the reduction of coffee bitterness after treatment can be a competitive advantage, and an economic boost to the industry. PARTICIPANTS: Ipanema Coffees from Brazil is acknowledged for contributing the coffee used in this study. This research targets the coffee industry. TARGET AUDIENCES: This research targets the coffee industry. The enhancement of flavor and reduction of bitterness after treatment can be a competitive advantage, and an economic boost to the industry. This work has been submitted to Annual Meetings of the Institute of Food Technologists. This work will support the degrees for one Masters student and one PHD student. PROJECT MODIFICATIONS: Performed a study on color of paprika while waiting for a new roaster. This allowed the PHD student to train and learn the machine vision system. Thus, the student was able to immediately perform his color work once the roaster came.

Impacts
Electron microscope images showed extensive modification at the surface of beans with enzyme treatment. These changes have been quantified using image analysis method. One initial problem was the ability to control the roasting process, a key process in coffee manufacturing. A new roaster that can precisely control the heating profile of the beans during roasting was used. Sensory tests were conducted to compare the coffee resulting from the treated beans to those from controls. The results of the sensory tests revealed that the treated beans resulted in coffee that had much more flavor, and had much less bitterness. This was confirmed by gas chromatographic data. The decrease in bitterness was not due to a loss of caffeine, since both the treated and control samples had the same levels of caffeine. The potential impact of this method is to improve the flavor volatiles, and decrease the bitterness of the coffee beans. Therefore marginal quality beans can be improved, and become economically important. While waiting for the roaster, the PHD student working of roasting and color of coffee beans performed experiments on color degradation of paprika to prepare for the color analysis of coffee roasting. Paprika is a mild, powdered seasoning made from drying and milling red pepper fruits, Capsicum annuum L. Paprika is one of the most used natural colorants in the food industry. Its commercial value depends on the characteristic red color of the product. This research was conducted to study the effect of particle size (fine, medium, and coarse) and storage (light and dark, oxygen and nitrogen headspace) on color degradation of commercial paprika stored up to 63 days. Color and visual texture was assessed using the machine vision system. Particle sizes played an important role in paprika's perceived color. Finely ground product has brighter red color (L=22.43, a=61.06, b=38.66) compared to a coarse product (L=20.16, a=58.71, b=34.69). The combination of oxygen and light has a detrimental effect on paprika pigments while the combination of light, dark and nitrogen showed little change in color. Coarse particles had greater color degradation, due mainly to greater access of oxygen and light. Regardless of particle size, absence of either oxygen or light can prevent color degradation of paprika. Coffee color was followed through roasting and two consecutive color changes were observed. Total phenolics increased during initial roasting followed by a small decrease during the final roasting stage. Antioxidant capacity was significantly (alpha=0.05) in final roasted coffee compared to the green coffee beans while free radical scavenging activity initially increased and then decreased during the intermediate stages of roasting. The correlation between temperature of coffee beans on color and antioxidant capacity will help in the decision making process for coffee roasting and support the coffee industries in the Carribean. A Master's thesis was completed as a result of the study and a PHD student is finishing their study on kinetic modeling of coffee roasting.

Publications

  • de Azeredo, A. Ramirez-Rodrigues, M. Plaza, M. and Balaban, M. 2008. Effect of particle size and storage conditions in color degradation of paprika (Capsicum annuum), 175-35, 2008 National IFT Meeting, New Orleans, LA. de Azeredo, A. Ramirez-Rodrigues, M. Marshall, M. and Balaban, M. 2009. Coffee roasting color analysis, 057-37, 2009 National IFT Meeting, Anaheim, CA. de Azeredo, A. Ramirez-Rodrigues, M. Marshall, M. and Balaban, M. 2009. Total phenolics and antioxidant capacity of coffee during roasting, 025-04, 2009 National IFT Meeting, Anaheim, CA.


Progress 09/15/07 to 09/14/08

Outputs
OUTPUTS: A method was developed to improve the quality attributes of raw coffee beans by treating them with acid and enzymes. The treated samples and the controls were analyzed by sensory tests, and by electron microscopy for changes as a result of treatment. An electronic nose was used to sniff the headspace of samples. A machine vision system was used to measure color of green and roasted beans before and after treatments. A Master's thesis was completed as a result of the study. One problem was the ability to control the roasting process, a key process in coffee manufacturing. A roaster that can precisely control the heating profile during roasting was purchased and it will be used to study color changes in coffee. Experiments were conducted to roast green coffee beans for a period of time. Samples were taken at various times through the roasting process and color of the beans was assessed using a Machine Vision system, a non-destructive method that can be used to evaluate colors in non-uniform surfaces. Changes in L*, a*, and b* values were used to develop a kinetic model of color changes during the roasting. Dissemination: This research targets the coffee industry. The enhancement of flavor, and the reduction of bitterness of the resulting coffee after treatment can be a competitive advantage, and an economic boost to the industry. This study will be submitted to the Annual Meeting of the Institute of Food Technologists that will be held in Anaheim, CA from June 6 to 10. PARTICIPANTS: This work will support the degrees for one Masters student and one PHD student. Ipanema Coffees from Brazil is acknowledged for contributing the coffee used in this work. TARGET AUDIENCES: This research targets the coffee industry. The enhancement of flavor, and the reduction of bitterness of the resulting coffee after treatment can be a competitive advantage, and an economic boost to the industry. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The electron microscope images showed extensive modification at the surface of the beans with enzyme treatment. These changes have been quantified using image analysis method. A new roaster that can precisely control the heating profile of the beans during roasting was used. Sensory tests were conducted to compare the coffee resulting from the treated beans to those from controls. The results of the sensory tests revealed that the treated beans resulted in coffee that had much more flavor, and had much less bitterness. This was confirmed by gas chromatographic data. The decrease in bitterness was not due to a loss of caffeine, since both the treated and control samples had the same levels of caffeine. The potential impact of this method is to improve the flavor volatiles, and decrease the bitterness of the coffee beans. Therefore marginal quality beans can be improved, and become economically important. While waiting for the roaster the PHD student working of roasting and color of coffee beans performed experiments on color degradation of paprika. Paprika is a mild, powdered seasoning made from drying and milling red pepper fruits, Capsicum annuum L. Paprika is one of the most used natural colorants in the food industry. Its commercial value depends on the characteristic red color of the product from the carotenoids pigments capsanthin and capsorubin. This research was conducted to study the effect of particle sizes (fine, medium, and coarse) and storage conditions (light and dark, oxygen and nitrogen headspace) on color degradation of commercial paprika stored for up to 63 days. Commercial paprika powder (Capsicum annuum L) was separated into three particle sizes: fine (less than 300mm), medium (300mm to 355mm), and coarse (greater than 355mm) by passing it through a set of sieves. The fractions were stored under four different conditions: light + oxygen, light + nitrogen, dark + oxygen, and dark + nitrogen for up to 63 days. Color was assessed using Machine Vision (MV), a non-destructive technique used to monitor color in non-uniform surfaces. Visual texture analysis was also conducted using MV. Particle sizes seem to play an important role in paprika's perceived color. Finely ground product has brighter red color (L=22.43, a=61.06, b=38.66) compared to a coarse product (L=20.16, a=58.71, b=34.69). The combination of oxygen and light has a detrimental effect on paprika pigments. After 63 days of storage in the presence of oxygen and light, DE value for fine, medium and coarse systems were 8.38, 9.96 and 16.79 respectively. No significant difference (a>0.05) was observed in color degradation under the storage conditions of light + nitrogen, dark + nitrogen, and dark + oxygen. Coarse particles had greater color degradation, due mainly to greater access of oxygen and light. Regardless of particle size, absence of either oxygen or light can prevent color degradation of paprika.

Publications

  • de Azeredo, A. Ramirez-Rodrigues, M. Plaza, M. and Balaban, M. 2008. Effect of particle size and storage conditions in color degradation of paprika (Capsicum annuum), 175-35, 2008 National IFT Meeting, New Orleans, LA.


Progress 09/15/06 to 09/14/07

Outputs
OUTPUTS: A method was developed to improve the quality attributes of raw coffee beans by treating them with acid and enzymes. The process emulates the digestive action of stomach and intestines on the beans. Experiments were conducted to treat the beans for a period of time (up to 24 hrs) with acid and proteolytic enzymes (such as pepsin). The treated samples and the controls were analyzed by sensory tests, and by electron microscopy for changes as a result of treatment. A method of image analysis was developed to quantify the changes at the surface characteristics of the beans. An electronic nose was used to sniff the headspace of samples. A machine vision system was used to measure color of green and roasted beans before and after treatments. A Master's thesis was completed as a result of the study so far. In the second year, it is intended to identify key flavor and volatile compounds that affect the quality of the beans, and determine the kinetics of their change as a result of the treatments. A Ph.D. student is working on these objectives. TARGET AUDIENCES: This research targets the coffee industry. The enhancement of flavor, and the reduction of bitterness of the resulting coffee after treatment can be a competitive advantage, and an economic boost to the industry.

Impacts
The electron microscope images showed extensive modification at the surface of the beans. These changes have been quantified using the image analysis method developed. Sensory tests were conducted to compare the coffee resulting from the treated beans to those from controls. A new roaster that can precisely control the heating profile of the beans during roasting was used. Without this roaster, comparison of the samples would be meaningless, since most of the flavor and aroma compounds in coffee develop as a result of roasting. The results of the sensory tests revealed that the treated beans resulted in coffee that had much more flavor, and had much less bitterness. This was confirmed by gas chromatographic data. The decrease in bitterness was not due to a loss of caffeine, since both the treated and control samples had the same levels of caffeine. Discriminant function analysis of e-nose data resulted in a good separation between treated and control samples. For green and roasted beans significant differences for L*, a*, and b* values were found between treated and control samples. The potential impact of this method is to improve the flavor / volatiles, and decrease the bitterness of the coffee beans. Therefore marginal quality beans can be improved, and become economically important.

Publications

  • Quality enhancement of coffee by acid and enzyme treatments. Luis Federico Martinez Valencia. 2007. M.Sc. Thesis. Food Science and Human Nutrition Dept. University of Florida.