Changes in Carrot Juice Components Bacteria

Food Sci. Technol.. Int., 2 (4), 246-252, 1996 Changes in Carrot Juice Components Due to Fermentation by Selected Lactic Acid Bacteria Hideki SAKAMOT0,1'2 Masaru KOGUCHI,2 YukioIsHIGUR02 and Tokichi MIYAKAWA1 1 Department of Fermentation Technology, Faculty of Engineering, Hiroshima University, Higashihiroshima 739, Japan 2Research Institute, Kagome Co., Ltd., 17, Nishitomiyama, Nishinasun(~mach~ Nasu-gun, Tochigi 329-27, Japan Received May 1 7, 1996 Lactic acid bacteria were evaluated for suitability in producing a fermented carrot juice. All nine strains of lactic acid bacteria studied grew well in the juice. Sensory evaluation indicated that L. delbrueckii subsp. bulgaricus IAM-1120 and L. helveticus JCM-1120 produced the most favorable juice. These strains produced less diacetyl, suggesting that the lack of diacetyl production is an important factor for acceptable fermented juice. Moreover, decreased aldehyde and increased ketone components of fermented carrot juice by these selected strains was observed by gas chromatography/mass spectrometry, and this was suggested to contribute to taste improve- ment. Although the color of the fermented juice changed in fresh orange color, there was no significant difference in carotenoid composition and their contents. Keywords: carrot juice, Iactic acid fermentation, diacetyl, color, carotenoid Lactic acid bacteria have a long history in food production, organoleptically-preferable lactic acid fermentation and the because lactic acid fermentation contributes to improved change in the components of carrot juice due to fermentation storage qualities, physical properties and flavor. Recently, the have not been adequately studied. physiological functions of lactic acid bacteria, such as reliev- In this study, Iactic acid bacteria suitable for the production ing intestinal disorders and having an immunostimulation of carrot juice were selected, and subsequent changes in the effect, have attracted public attention (Benno, 1994). Typical carrot juice components due to fermentation were evaluated. examples of foods produced using lactic acid bacteria include More detailed chemical analysis was done on the juice processed dairy products (e.g., cheese, yogurt), traditional products of specific strains which sensory panelists preferred. feamented cereal products (e.g., miso, soy sauce, sake) and processed meat products (e.g., sausage, etc.). It is interesting to Materials and Methods note that lactic acid bacteria selected for these foods vary Preparation of carrot juice Carrot juice was prepared depending on the food materials (Nakano, 1967). For by the following process in the Kagome Research Institute production of lactic acid fermented vegetable products such pilot plant, Tochigi. Carrots (variety: Kuroda-5-sun) ob- as sauerkraut and pickles (Daeschel & Fleming, 1984), tained from a local market were washed, blanched in a hot halotolerant lactic acid bacteria of the groups Pediococcus or water at 90'C for 30 min and lye-peeled by a roller-type Lactobacillus are used and give the products a specific fiavor. peeling machine. They were crushed into small pieces (aver- However, there were few reports about the lactic acid bacteria age size 2-3 mm) using a micrograder Model MR-130 (5 mm suitable for vegetable juice applications. screen size, Seiken Co., Ltd., Tokyo) heated to 85'C and In this study, Iactic acid fermentation was examined using centrifuged by decanter Model HS-204LS (IHI Co., Ltd., carrots as a substrate. Among vegetables, carrots are the Tokyo) at 3,000 rpm for 10min. After pasteurization at richest in p-carotene compounds, which are attributed to l05'C for 30 s by a plate-type heat exchanger Model MRS-2 providing certain health effects (Hart & Scott, 1995). Because (Hisaka, Works Ltd., Osaka), the juice was concentrated to carrots contain only a small amount of organic acids, carrot 36% Brix by evaporator Model CT-1B (Alfa Laval Co., Ltd., juice (pH 5.6-6.0) is a low acid food and requires retort Lund, Sweden) at 60'C 55 cmHg pressure. The mass obtained sterilization after canning for storage. However, this steriliza- was packed in a polyethylenefilm bags and stored at -20'C tion method causes quality deterioration of carrot juice due to in a freezer. severe heat treatment and is an inefficient process for commer- Before each experiment, concentrated carrot juice was cial production. In contrast, Iactic acid ferrnentation changes thawed in a cold room (5'C) and diluted with distilled water the fiavor and results in a more acidic juice which may not to 6.5% Brix, which corresponded to raw carrot juice. This require as much heat processing. carrot juice was poured into Erlenmeyer flasks, pasteurized in To date, malolactic fermentation of carrot juice by the hot water (95'C, 5 min) and cooled rapidly under running tap addition of malic acid (Takanami et al, 199 l) and traditional water. Indian lactic acid fermented beverage (kanji) from black Microorganisms and media Lactic acid bacteria used carrot (Berry et al, 1 989) have been reported. However, in this study belong to 6 types of genera Lactobacillus, Lactic Acid Ferrnentation of Carrot Juice 247 Enterococcus faecalis I FO- 1 2694, Leuconostoc mesen teroides Volatile analysis Volatile components were analyzed IFO- 1 2060, and Streptococcus thermophilus IF0-3535. The by GC-MS using an HP 5972A (Hewlett-Packard Co., Palo six Lactobacillus strains used were L. acidophilus IFO- 1 395 1 , Alto, CA, USA) mass spectrometer fitted with an HP 5890 L. delbrueckii subsp. bulgaricus (L. bulgaricus) IAM- I 1 20, L. series 11 GC and an HP Chemstation data system. Carrot casei IAM-1045, L. delbrueckii subsp. delbrueckii (L. del- juices were centrifuged at 8,000 rpm for 5 min, and the brueckii) IFO- I 085, L. helveticus JCM-1 120 and L. planta- supernatants were diluted 1:10 with distilled water. The rum IF0-3070. mixture of 10 ml diluted sample and 5 pl o-dichlorobenzene/ MRS broth (Man et al, 1960) was used for lactic acid benzyl alcohol (0.012%, v/v) solution as an internal standard bacteria growth. BL agar medium (Eiken Chemical Co., Ltd., were put into a 25 ml glass tube. The tube was connected to Tokyo) was used for the determination of the viable cell a Purge & Trap Concentrator LSC-2000 (Tekmar Co., population as colony foaming units (cfu)/ml after cultivation Cincinati, OH, USA) and held at 60'C. On purging with for 48 h at 30'C under anaerobic conditions (BBL Gas Pak, helium gas (40 ml/min) for 60 min, the gases generated were H2+C02 anaerobic system, Japan Becton Dickinson Co., trapped onto a Tenax-TA (GL Science Inc., Tokyo) tube. Ltd., Tokyo). After 15 min of helium gas aeration for dehydration, the tube Fermentation of carrot juice Lactic acid bacteria were was heated at 200'C for 6 min to desorb the volatiles. Then the first pre-incubated in MRS medium. The bacteria were volatiles were cryofocused at - 100'C and directly introduced inoculated into 100ml of medium in a 200 ml fiask and into the analyzer with a capillary column J & W DB-WAX stationarily Incubated at 37'C for 20 h in a water bath. The (30 mX0.25 mm i.d., df=0.5 pm) at 200'C for 2 min. The bacteria showing slower growth were activated by repeating temperature program was isothermal for I min at 40'C and the above procedure. Precultures were prepared by inocula- was then raised to 190'C at 3'C/min. The detector tempera- tion of MRS culture into 100 ml of reconstituted carrot juice ture was 250'C. The ionization voltage was 70 eV (EI mode), in a 200 ml Erlenmeyer fiask at an inoculum ratio of 3% (v/ and the mass range was m/z 35-300. Determination of the v) and by incubation under the same conditions as mentioned diacetyl concentration was done based on standard curves above. obtained by the same method, using O. l, 0.5, I .O and 2.0 ppm For the fermentation test, these precultures were used by diacetyl solutions. inoculation similarly into 200 ml of reconstituted carrot juice Sensory evaluation Each fermented carrot juice was in a 500 ml Erlenmeyer fiask at an inoculum ratio of 3% (v/ evaluated by the paired-preference test (Yamaguchi, 1973), v) and stationary incubation at 37'C for 20 h in the incubator. using non- fermented carrot juice as a control with 1 5 trained After fermentation, all juices, including non-fermented con- sensory panelists. Samples were kept in a glass bottle at 20'C trol samples were filled into 200 ml glass bottles and pasteur- and were tested under a red lamp to distinguish the difference ized at 95'C for 5 min. They were stored in a 5'C cold room in color. Panelists were also asked to describe their reasons for until each analysis. selection. Statistical analyses were judged by the two-tailed Chemica/ analysis Total acidity was determined by test. titration with O. I N NaOH and expressed as percent lactic Color and carotenoid analysis The color of treated acid. The pH measurements were made with a pH meter F- 12 carrot juice was measured by a Hunter color difference meter (Horiba Ltd., Kyoto) equipped with a glass electrode. ND-~80 (Nippon Denshoku Ind. Co., Ltd., Tokyo). The Individual organic acids (citric, acetic, Iactic and malic) absorption spectra of the juice were analyzed using a U-32 lO were determined by HPLC using a Shodex A0-30 system spectrophotometer (Hitachi, Ltd.). The analysis of a-, and (Showa Denko K.K., Tokyo) and an 8cX300 mm Lonpack ~-carotene content and the composition of carotenoids was KC-81 1 separating column at 80'C. Samples were diluted I :3 done by the reversed phase HPLC technique, after extracting and a 20 pl aliquot was injected after filtration using a the carotenoids frorn the juice samples.

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