QUALITY IMPROVEMENT OF COCOA (THEOBROMA CACAO) USING CONTROLLED SECONDARY FERMENTATION METHOD WITH ADDITIONN OF YEAST AND LEMON PEEL (CITRUS LIMON)

• Main Author: Dwiananta Yusantri, Sonia
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70508
• Institution: Institut Teknologi Bandung

Fermentation is one of the crucial steps in determining the final quality and the development of fine flavor precursors in cacao bean. Cacao bean quality and flavor are inconsistent since cacao farmers use natural fermentation method. The involvement of yeast, lactic acid bacteria, and acetic acid bacteria during cacao fermentation will produce cocoa products with distinct flavor. Secondary fermentation is a strategy for enhancing the quality of fermented cacao beans. This study aims to carry out secondary fermentation to ferment cocoa beans with the addition of a single yeast starter (Candida tropicalis) and dried lemon fruit or fresh lemon peel (Citrus limon) in various variations and determine the effect of the process on changes in the sugar, ethanol, organic acids, amino acids, total phenolics, quality, and flavor. Single yeast starter is added to stimulate the alcoholic process thus enhance the quality of the cacao beans. Lemon is added as a substrate for yeast during secondary fermentation and produce a new flavour in cacao beans. Secondary fermentation uses Forastero cacao beans from North Lombok that have been fermented naturally by farmers. The addition of a single yeast starter (Candida tropicalis) was 10 % (v/w) inoculum with a cell density of 107 cells/ml.The screening stage was carried out on a small scale using dried fruit or fresh lemon peel with each variations in the amount of 2 % (w/w), 4 % (w/w), and 6 % (w/w). The process was carried out in a controlled manner in a closed plastic box (17 x 11,5 x 5 cm) in an incubator at ± 30 °C. During fermentation the pH, temperature, CO2 content, relative humidity, microbial enumeration, cacao bean weight loss and fermentation index were observed at 0, 2, 4, 6, 8 and 10 hours. The scale-up also carried out in a same controlled fermentation in a closed plastic jar (circle radius 17 cm x height 20 cm) but were observed at 0, 30, 60, 90 and 120 minutes. The quality of fermented cacao beans was measured by the number of beans/ 100-gram which was compared to SNI 01- 2323:2008/ Amd 1:2010 standard. Moisture content of beans was measured by gravimetric test which was compared to SNI 2323-2008 standard. The pH level was measured with a pH meter. Sugar, ethanol, and organoc acid content was measured using High Performance Liquid Chromatography (HPLC). Amino acid content was measured using Ultra Performance Liquid Chromatography (UPLC). Total phenolic content was measured using Folin-Ciocalteau reagent. Organoleptic testing of secondary fermented cacao powder was performed on trained panelists. The screening results showed an increase in the quality of cacao beans from natural fermentation which had B quality to AA quality with 2% dried fruit and 2% lemon peel, and A quality with 4% and 6% lemon peel. The moisture content showed that all dried cacao beans are into the range (< 7,5%), where the addition of 2%, 4%, and 6% dried fruit respectively resulted a moisture content value at 5,16 ± 0,51%, 2,46 ± 0,14%, and 2,48 ± 0,13%. For the addition of 2%, 4%, and 6% lemon peel respectively resulted a moisture content value at 5,24 ± 0,44%, 5,15 ± 0,52%, and 4,28 ± 0,97%. The scaleup stage was determined by the highest fermentation index, which was achieved at 100 % by adding fresh lemon peel at 4% and 6% for 2 hours of fermentation. This showed an increase in the quality of cacao beans from natural fermentation which had A quality to AA quality. With 4% lemon peel at the 30th minute of fermentation and 6% lemon peel at the 60th minute of fermentation, the highest fermentation index reached 85%. The moisture content showed that both results were still into the range, with lemon peel 4% and 6% was 3,72 ± 1,06% and 3,63 ± 1,86%. The dry seed pH measured values were 5,48 ± 0,06 and 5,14 ± 0,01, respectively. Total phenolic showed an increase along with the length of secondary fermentation time, which was 344,64 ± 7,23 mg GAE/g for 4% lemon peel and 382,58 ± 0,00 mg GAE/g for 6% lemon peel. With the addition of 4% lemon peel, the total amino acids for sweet taste was 28,56 mg/g, bitter was 36,82 mg/g, and acid was 9,36 mg/g. While the addition of 6% lemon peel, the total amino acids for sweet taste was 28,29 mg/g, bitter was 33,72 mg/g, and acid was 8,63 mg/g. The organoleptic results of 4% lemon peel had the highest global score which 7,00 compared to 6% lemon peel with 6,50 and natural fermentation with 6,00. Lemon peel 4% showed the score taste of fresh fruit 2,5 and dried fruit 1,0. This research shows the potential of secondary fermentation to improve the quality and create new flavors of cocoa that is not yet perfect from natural fermentation.