초록

○ 연구결과
10종의 신선절단 채소류의 유통현황과 품질, 미생물적 현황과 문제점을 검토하였으며 이를 토대로 우수한 품질의 최소가공 제품유통을 위한 적합 갈변방지기술의 확보, 가공 및 유통 중 미생물 저감화를 통한 안전성 확보를 위한 기초기술을 확보하였음

Abstract ▼

Ⅳ. Results and Recommendation
1. Development of quality keeping and packaging method for fresh-cut vegetable produces during distribution
1) Investigation of present market conditions and quality changes of fresh-cut vegetables
The most of fresh-cut vegetables were sold at big supermarket w

Ⅳ. Results and Recommendation
1. Development of quality keeping and packaging method for fresh-cut vegetable produces during distribution
1) Investigation of present market conditions and quality changes of fresh-cut vegetables
The most of fresh-cut vegetables were sold at big supermarket was prepared by washing, peeling, cutting and wrapping in its own company and stored below 10℃ with high quality and safe comparatively, but there was no inscription for pretreatment methods and shelf-life of the products. Browning and some quality deterioration were occurred in lettuce, peeled potato and garlic during the distribution at market. The products sold at traditional market place was stored in room temperature, with quality deterioration like browning and without any inscription of pretreatment methods, date of preparation and shelf-life.
2) Development of pretreatment and processing techniques for fresh-cut vegetables with higher quality
Ascorbic acid, citric acid, sodium chloride and magnesium chloride were effective in preventing browning of fresh-cut vegetables, but the efficacy was different according to commodities. Blanching was effective treatment in preventing the browning of fresh-cut burdock and lotus root. When the ozone was cotreated with chemical antibrowning agents, the efficacy of browning inhibition was improved. When the products were processed at low temperature (below 4℃), the browning was more inhibited than the products processed at room temperature. Natural compounds for preventing enzymatic browning of fresh-cut vegetables were screened. Green tea extract(2%), polyphenol from green tea(0.5%), catechin(25mM) and polyphenon(5-10%) were more effective than ascorbic acid(1%) in preventing browning. Extract from kiwi fruit was effective for mushrooms. Among the oriental herbs, extract from asparagi radix, cassia, astragali radix and chinese yam were effective in both of browning and softening inhibition of mushroom.
3) Effects of cutting method and condition to quality
Strip cutting of sweet pumpkin caused more rapid reduce in hardness and titratable acidity than slicecutting during storage. Cutting with sharp knife was effective in browning prevention of cabbage than dull knife cutting.
4) Browning inhibition of cut surface in fresh-cut vegetables
Ascorbic acid, citric acid, sodium chloride and magnesium chloride and its composite(1:1:1:1, w/w) inhibited browning of cut surface. The effective antibrowning agents for commodities used in this experiment were as follows, burdock and lotus root;Ascorbic acid(3%), citric acid(2%) and malic acid(3%), potato;cystein(1%), sodium and magnesium chloride(1%) and ozone co-treatment, garlic;cystein(0.5%), platycodon;cystein(1%), cabbage;magnesium chloride(0.5%), lettuce and chicory;citric acid(0.5%), Agaricus bisporus;ascorbic acid(1%), extract from cnidium officinale, cassia and kiwi, Pleurotus ostreatus;ascorbic acid(1%), cysteine(1%), extracts from cnidium officinale, astragali radix and chinese yam, sweet pumpkin;ascorbic acid(1%), sodium chloride(1%), and magnesium chloride1%).
5) Quality evaluation of fresh-cut vegetables during storage
Fresh-cut vegetables processed by washing, cutting and dipping in suitable antibrowning agents were stored at 4℃ and the changes of quality attributes were measured during storage, root vegetables(burdock, lotus root) and garlic kept without browning for 2 weeks. The browning degree of potato was increased only 4% after 2 weeks storage, but the browning was occurred just after 1 or 2 days of storage in leaf vegetables. Hardness, pH, titratable acidity and color were different according to commodities.
6) Screening of adequate packaging method and materials for fresh-cut vegetables LDPE(low density polyethylene) film packaging was effective for the quality attributes (weight loss, respiration rate, hardness, browning degree and organoleptic quality) of mushroom during storage, but HDPE(high density polyethylene) film was effective for cabbage. Vacuum packaging of garlic and sweet pumpkin stimulated browning and softening.
2. Establishment of Microbiological Quality Safety of Commercially Available Ready to Eat Vegetables
1) Microbiological Characteristics of Commercially Available Ready to Use Vegetables
The microbial distribution of 9 kinds of ready to use(RTE) vegetables(cichorium intybus, sweet pumpkin, lotus root, garlic, mushroom, burdock, chinese bellflower, chinese cabbage, lettuce) were determined and total counts ranged from 10⁵ to 10⁷ CFU/g, respectively. Among them, the cichorium intybus showed the highest initial total counts of 7.45 log CFU/g, whereas the least initial total counts of 5.11 log CFU/g in garlic was observed. Initial yeast and molds of the RTE vegetables ranged from 10⁵ to 10⁸ CFU/g and a chinese bellflower had highest initial numbers of 8.03 log CFU/g, whereas the least numbers of 5.26 log CFU/g in gallic was observed. Coliforms ranged from 10² to 10⁸ CFU/g, except for burdock and no E.coli was enumerated. Averall, a chinese bellflower had the highest initial microbial flora among 9 samples. In the meantime, the total counts of the 9 RTE vegetables increased up to 10⁸ to 10¹⁰ CFU/g at 4oC after 7 d storage, whereas total counts were rapidly grown up to 10⁹ to 10¹⁰ CFU/g at 25oC after 4 d storage.
RTE vegetable samples commercially available in Korea were analyzed for the presence of Yersinia spp. and Listeria spp. by the conventional Food and Drug Administration protocol, and presumptive strains were identified by morphological, cultural and biochemical tests according to Bergey's manual and confirmed by API-Listeria kit. Also, serotypes, susceptibility to 12 antibiotics and virulence test using polymerase chain reaction were tested. Among the total 673 RTE vegetable samples, 27 samples (4.0%) were found to be contaminated with Yersinia species.
Among the 27 strains of Yersinia spp. isolates, 18 strains (2.7%) for Yersinia enterocolitica, 5 strains (0.5%) for Y. frederiksenii, 3 strains (0.7%) for Y. intermedia, and 1 strain (0.1%) for Y. agglomerance were identified, respectively. Of 40 Yersinia spp. isolates, Y. enterocolitica (67%) was the most predominant species in the RTE vegetable samples compared to other Yersinia species. According to serotypes of Y. enterocolitica isolates, O:3 (11.1%) and O:5 (11.1%) was the most predominant, respectively and followed by O:8 (5.6%) and others (72.2%). An antibiotic susceptibility test showed that Yersinia spp. isolates were very susceptible to the antibiotics tested, but they were very strongly resistant to ampicillin (94%), cephalothin (100%) and carbenicillin (83%), respectively. PCR with specific primers derived from yst of Y. enterocolitica and Hep-2 cell invasion assay were applied to confirm the pathogenic Y. enterocolitica, respectively. Among 18 strains of Yersinia enterocolitica isolates, PCR analysis showed that 16.7% (3 strains) of the Y. enterocolitica isolates proved to be pathogenic. Also, Hep-2 cell invasion assay showed 3 strains to be pathogenic, but different pathogenicity was observed compared to that of PCR. Among total 402 vegetable samples, 17 samples (4.2%) were found to be contaminated with Listeria species. Among the 17 strains of Listeria spp. isolates, only 2 strains (0.5%) for L. monocytogenes and 15 strains (3.7%) for L. innocua were identified, respectively. Of 17 Listeria spp. isolates, L. innocua (88.2%) was the most predominant species in the RTE vegetable samples compared to other Listeria species. Also, antibiotic susceptibility test showed that Listeria spp. isolates were very susceptible to the antibiotics tested, except for nalidixic acid. PCR with specific primers derived from hly of L. monocytogenes and an in vitro virulence assay were performed, Among 17 strains of Listeria spp., PCR analysis showed that 2 strains of L. monocytogenes isolates proved to be pathogenic, but none of L.innocua showed pathogenicity. Also, hybridoma Ped-2E9 cells assay showed that only L. monocytogenes isolates killed approximately 95-99% hybridoma cells after 6h, but L. innocua isolates had about 0-5% lethal effect.
2) Microbiological Assurance of Quality and Preservation by Pre-treatment and Packaging
Inactivation effects of ozone or organic acids on the microflora of lettuce and mushroom were analyzed. Water washing reduced the total counts and yeast and molds on the lettuce by 0.15 and 0.4 log CFU/g, but 3 ppm ozone treatment significantly enhanced the inactivation effects by 2.89 and 2.79 log CFU/g reduction, respectively. The the total counts and yeast and molds on enoki mushroom were more resistant to ozone treatment than that of lettuce at the same treatment. Inactivation effects of ozone on lettuce or enoki mushroom increased as ozone concentrations and dipping time increased, but the greatest inactivation effect was observed at 3 ppm ozone treatment for 3 min. When E. coli O157:H7 inoculated into lettuce was treated with 1 to 5 ppm ozone for designated dipping time, the optimal condition for the reduction of the pathogen was 3 ppm ozone for 3 min and L. monocytogenes was more resistant than that of E. coli O157:H7 at the same condition. Also, 3 ppm ozone treatment reduced significantly the number of E. coli O157:H7 inoculated into lettuce by 2 log CFU/g, but little inactivation effect was observed in enoki mushroom. Thus, this results show that inactivation effect of ozone on the foodborne pathogens could be different from types of organisms, types of foods and environments.
In the meantime, organic acids treatments (1% acetic, 1% citric and 1% lactic acid) for 1.5 min reduced the total counts on the lettuce by 1.63, 1.89 and 2.05 log CFU/g, but the combined 3 ppm ozone with each organic acid treatments significantly enhanced the inactivation effects by 3.0, 3.69 and 3.31 log CFU/g reduction, respectively. Similar results were observed in the yeast and molds and the strongest synergistic inactivation effects was occurred at the combined treatment of 3ppm ozone and 1% citric acid. The the total counts and yeast and molds on enoki mushroom were more resistant to combination of 3 ppm ozone and 1% citric acid than that of lettuce at the same treatment. On the other hand, when E. coli O157:H7 inoculated into lettuce and enoki mushroom were treated with combined 3 ppm ozone with 1% organic acids, the combined treatment showed the 3 times and 2 times stronger inactivation effects than those of single treatment of organic acid alone, respectively. Similar pattern was observed in L. monocytogenes inoculated into lettuce and enoki mushroom, but the inactivation effect of L.monocytogenes was significantly more decreased than that of E. coli O157:H7 at the same condition.
The growth of total counts on the lettuce or enoki mushroom by 3 ppm ozone and 1% citric acid, singly or combined during storage at 5℃ and 15℃ for 14 days are determined. When lettuce was stored at 5℃, the total counts in combined treatment significantly reduced up to 10 d storage compared with single treatment, but enhanced inactivation effect was observed only up to 3 d storage at 15℃ and similar growth was occurred after 7 d storage. Also, similar pattern was observe in the yeast and molds. When E. coli O157:H7 or L. monocytogenes inoculated into the lettuce by 3 ppm ozone and 1% citric acid, singly or combined were stored at 5℃ for 14 days, the combined treatment significantly reduced the growth of the pathogens up to 7d storage compared with single treatment, but similar growth was occurred after 7 d storage. Similar patterns were observed in enoki mushroom, the growth of the pathogens in enoki mushroom was more faster than that of lettuce. In the meantime, there was little influence on the growth inhibition of microorganisms between general packaging and micro perforated film packaging in the pre-treated lettuce and enoki mushroom during storage at 5℃ and 15℃.

목차 Contents

• 제출문 ... 1
• 요약문 ... 3
• SUMMARY ... 11
• CONTENTS ... 20
• 목차 ... 23
• 제1장 연구개발과제의 개요 ... 25
• 1절 연구개발의 필요성 ... 25
• 1. 기술적 측면 ... 25
• 2. 경제·산업적 측면 ... 25
• 3. 사회·문화적 측면 ... 26
• 2절 연구개발 내용 및 범위 ... 27
• 제2장 국내외 기술개발 현황 ... 29
• 제3장 연구개발수행 내용 및 결과 ... 31
• 1절 연구 수행 방법 ... 31
• 1. 신선편이 채소류 제품의 유통 중 고품질 유지방법의 개발 및 적정 포장기술 확립 ... 31
• 가. 재료 및 최소가공처리 ... 31
• 나. 갈변도 및 색도 측정 ... 31
• 다. 포장내부의 가스분석 ... 32
• 라. 경도 측정 ... 32
• 마. pH, 가용성고형분 및 적정 산도 측정 ... 32
• 바. 총페놀 함량 측정 ... 33
• 사. PPO (polyphenol oxidase) 활성 측정 ... 33
• 아. 관능검사 ... 33
• 2. 신선편이 채소류 제품의 유통 중 미생물적 안전성 확립 ... 34
• 가. 시료의 채취 ... 34
• 나. 시판 신선편이 야채류로부터 미생물 균총 분석 ... 34
• 다. 시판 신선편이 야채류로부터 병원성균의 분리 동정 ... 35
• 라. 양상치와 팽이버섯에 균주 접종 ... 39
• 마. 오존수의 생성과 생성량 ... 40
• 바. 미생물의 처리와 분석 ... 41
• 사. 포장재별 미생물 저감화 ... 42
• 2절 연구 내용 및 결과 ... 43
• 1. 신선편이 채소류 제품의 현황 조사 및 유통 중 고품질 유지방법의 개발 및 적정 포장 기술 확립 ... 43
• 가. 시판 신선편이 채소류 제품의 현황 조사 및 유통 중 품질변화 조사 ... 43
• 나. 고품질 신선편이 채소류 가공제품을 위한 전처리 기술 및 가공기술 개발 ... 49
• 1) 화학적 방법이 갈변에 미치는 영향 ... 49
• 2) 물리적 방법이 갈변에 미치는 영향 ... 61
• 3) 저온가공이 품질 특성에 미치는 영향 ... 65
• 4) 천연추출물이 신선절단 채소류의 품질특성에 미치는 영향 ... 68
• 5) 신선 절단방법이 채소류의 품질에 미치는 영향 ... 82
• 6) 신선편이 채소류의 고품질 유지를 위한 품목별 최적 조성물의 개발 ... 89
• 7) 적정 포장 방법의 검토 및 적용 시 품질 변화 ... 95
• 8) 관능적 평가 ... 104
• 2. 신선편이 채소류 제품의 유통 중 미생물적 안전성 확립 ... 108
• 가. 온도변화에 따른 시판 신선편이 채소류의 각종 미생물 현황 조사 ... 108
• 나. 부패 및 병원성 미생물의 분리·동정 및 생화학적 특성 분석 ... 113
• 다. 양상치와 팽이버섯에 대한 오존 효과 ... 120
• 라. 전처리 및 포장의 병용처리시 미생물 생육변화 ... 131
• 마. 저장온도에 따른 미생물의 성장 ... 135
• 제4장 참고문헌 ... 144
• 끝페이지 ... 150