The results were compared with the typical semi-continuous extraction method. C ylin d er. PG-1. PG-3. PG-2. PG-4. Heater. Heater. Pomp. Gas meter. S eparato.
EXTRACTION OF FUNCTIONAL INGREDIENTS AND FRAGRANCE FROM CITRUS PEEL Yukihiro Kawamoto1, 2, Siti Machmudah1, 3, Rintarou Hoshino2, Syoji Hirayama2, Masahiro Tanaka2, Munehiro Hoshino4, Motonobu Goto1
1
Department of Chemical Engineering, Nagoya University, 464-8603, Japan
2
ASCII Co. Ltd., 827-0004, Japan
3
Sepuluh Nopember Institute of Technology, Surabaya 60111, Indonesia
4
Maruboshi Vinegar Co., Ltd., 827-0004, Japan
1. INTRODUCTION
Citrus is loved all over the world. There is a culture, which has been familiar to many kinds of sour citrus having distinct aroma in Japan. Its juice has been used in food products such as sauces and chilled sweets because of its unique and desirable flavor. The residue of citrus juice is mainly composed of peel, juice sack and seed. Notably, the peel contains valuable compounds, such as essential oil and flavones. Most of citrus essential oils and flavones have been left to remain in peel part. In this work a more efficient extraction method of the citrus ingredients and fragrances from peel part of the typical Japanese sour citruses, Citrus junos(Yuzu), Citrus sphaerocarpa(Kabosu), Citrus tamurana(Hyuganatsu), and Citrus aurantium(Daidai) using supercritical carbon dioxide(SC-CO2). The aromatic components contained in the essential oils of citruses are hydrocarbons with various structures such as monoterpenes, sesquiterpenes, and their oxygenated compounds. SC-CO2 has low critical temperature, low viscosity and it is easy to separate from the extract. In this study, we have developed a batch extraction method. The results were compared with the typical semi-continuous extraction method.
PG-1
PG-2
PG-3
PG-4
Gas meter BPR1
BPR3
Heater
Heater
Flow meter
Cooling bath
Heater
Separato Separator r
Extractor
Thermostat heater
CO Cylinder 2 Cylinder
Thermostat heater
Heater
BPR2
Pomp Pump
Chiller unit
Fig 1. Schematic diagram of SC-CO2 extraction apparatus
2. EXPERIMENT
2.1 MATERIALS
Sample of daidai fruit was harvested in Japan. The outer daidai peel was scraped automatically using a skinning machine (KR-ROBO-03, MITSUWA Co. Ltd., Niigata) which separate the flavedo part containing albedo. Its peel was scraped, placed inside an air-tight wrapping plastic bag, and then stored in a freezer at -20oC until extraction experiments were performed. No pre-drying treatment was carried out on the sample. The feed material contained water of approximately 80wt%. Prior to extraction experiments, the sample was gently thawed to room temperature.
2.2 Steam distillation
Approximately 40 g of scraped citrus peel was minced in 500 mL of distilled water, and placed into a 1L round flask. The flask was then connected to a distilling receiver for essential oil testing with Liebig condenser. Distillation was carried out at a temperature of 100oC for 24 h.
2.3 SC-CO2 extraction A semi-continuous flow SC-CO2 extraction apparatus (AKICO Co., Ltd., Tokyo) shown in schematic diagram in Fig. 1, was used in the experiments. Approximately 80 g of scraped citrus peel was placed in a 500 mL extractor having a height of 20 cm and inside diameter of 7 cm. Liquid CO2 from a cylinder with siphon attachment was passed through a chiller kept at 0oC, and compressed CO2 was flowed into the extractor covered by a thermostat heater that was maintained at the operating temperature. The supplied pressure of liquid CO2 was controlled by back-pressure regulator (BPR) 1, while the pressure in the extractor was controlled by BPR 2. The exit fluid from the extractor was expanded to a pressurized separator at 2 MPa and 0oC by BPR 3. CO2 flow rate was measured by a flow meter and a dry gas meter. Extracted oil was collected from the pressurized separator every 60 min for a total extraction time of 300 min, and weighed right after the collection. In the case of batch-wise extraction, the pressure was controlled in step wise consisted of a series of pressurization period, static high pressure period and depressurization period. In the static period, CO2 flow was stopped. The static period of step-wise pressure controlling extraction was set to 60 min. After the holding time, which allowed CO2 to penetrate into the sample matrix has elapsed, the system was depressurized to ambient, while collecting essential oil at the separator. These series of batch-wise pressurization-static-depressurization steps were conducted six times under various conditions. Extraction experiments were carried out at temperatures of 40, 60 and 80oC, pressures of 10, 20 and 30 MPa.
2.4 Recovery of extracted oil
The recovery (%) was defined as the weight of extracted oils per weight of oil obtained by steam distillation as shown below. Yield (%) =
weight of extracted oil weight of Steam distilled oil
× 100
2.5 Quantitative analysis of flavones Aqueous layer of the extracts were analyzed using a HPLC LC-10AD gradient system, equipped with Diode Array Detector SDP-M10A. Inertsil ODS-3 column was used for separation at 35oC. The mobile phase consisted of solvent A, 0.1 % acetic acid in water, and solvent B, 0.1 % acetic acid in acetonitrile (acetonitrile/water = 75/25, v/v). The flow rate was 1.0 mL/min. As shown in Table1, the gradient elution was carried out according to the following steps: time 0 min A-B (88:12); time 18 min A-B (78:22); time 28 min A-B (72:28); time 35 min A-B (62:38), time 48 min A-B (52:48), time 58 min A-B (0:100); time 70 min A-B (88:12). Peaks were measured at a wavelength of 285 nm to quantify flavones.
3. RESULT AND DISCUSSION
3.1 Comparison of recovery rate for each extraction method
The extract was collected in two layers consisting of the oil layer and water layer. Essential oils and flavones were able to recover in each layer, respectively. The essential oil extraction was carried out with a variety of citrus peel as a raw material. Fig.2 shows the effect of difference of extraction methods on the rate of essential oil recovery in the optimal extraction conditions. As a result, the batch-wise extraction method was higher than in the recovery rate for all citrus peel. Moreover, the recovery rates of essential oil obtained from all peel were more than 90%. By treatment under static pressurized condition, raw material underwent swelling under supercritical CO2 conditions. It was thought that SC-CO2 penetrated and diffused through the cell matrix with the target essential oil, and was highly dependent on density changes during depressurization step. 3.2 Extraction behavior of hesperidin
The amount of water derived from the raw material tended to increase with increasing temperature and increase with increasing pressure. Approximately 50% of water relative to the weight of the raw material has been extracted. It has been found that the flavonoid component is contained in the aqueous layer. Fig.3
shows the recovery of flavonoid glycoside hesperidin from Citrus junos peel under the condition of 80oC, 30MPa. Hesperidin have bioactivities such as hypolipidemic effect and apoptosis inducing effect in cancer cell [1].
100
Recovery [%]
80 60
Batch wise Semi-batch
40 20 0 Citrus Junos
Citrus Citrus sphaerocarpa tamurana
Citrus aurantium
Recovery of Hesperidin [%]
Fig.2 Effect of extraction method on the recovery of essential oil
80
80oC, 30MPa
70 60 50 40 30 20 10 0
1
2
3
4
5
6
Fraction
Fig.3 Recovery of hesperidin contained in the aqueous layer 4. CONCLUSION
The batch-wise approach was found suitable for SC-CO2 extraction of essential oil from various Japanese citrus peel like compared to that of the typical semi-continuous method. Batch-wise method was superior technique in the recovery rate of essential oil. In addition, the water layer portion include hesperidin.
REFFERENCES
[1] S. Kanno, A. Shouji, K. Asou, and M. Ishikawa, .J. Pharm. Sci., 92, 166–170 (2003)
