Food ChemistryVolume 190, 1 January

Food Chemistry
Volume 190, 1 January 2016, Pages 755–762

Cover image
Influence of fermentation on glucosinolates and glucobrassicin degradation products in sauerkraut

Kalpana Palania, , , Britta Harbaum-Piaydaa, Diana Meskeb, Julia Katharina Kepplera, Wilhelm Bockelmannb, Knut J. Hellerb, Karin Schwarza
Show more
doi:10.1016/j.foodchem.2015.06.012
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Highlights
•
The influence of fermentation time on glucosinolates (GLS) was monitored for the first time.
•
Fermentation leads to complete degradation of GLS and decreased content of indole-3-acetonitrile.
•
Fermentation increases ascorbigen and indole-3-carbinol content, and storage period decreases their content.
Abstract
A systematic investigation was carried out on the influence of fermentation on glucosinolates and their degradation products from fresh raw cabbage, throughout fermentation at 20 °C and storage at 4 °C. Glucosinolates were degraded dramatically between Day 2 and 5 of fermentation and by Day 7 there was no detectable amount of glucosinolates left. Fermentation led to formation of potential bioactive compounds ascorbigen (13.0 μmol/100 g FW) and indole-3-carbinol (4.52 μmol/100 g FW) with their higher concentrations from Day 5 to Day 9. However, during storage indole-3-carbinol slowly degraded to 0.68 μmol/100 g FW, while ascorbigen was relatively stable from Week 4 until Week 8 at 6.78 μmol/100 g FW. In contrast, the content of indole-3-acetonitrile decreased rapidly during fermentation from 3.6 to 0.14 μmol/100 g FW. The results imply a maximum of health beneficial compounds after fermentation (7–9 days) in contrast to raw cabbage or stored sauerkraut.

Keywords
Fermentation; White cabbage; Sauerkraut; Glucosinolates; Glucobrassicin degradation products; Ascorbigen; Indole-3-carbinol; Indole-3-acetonitrile; Bioactive compounds; Lactic acid bacteria
1. Introduction
Epidemiological studies have shown that regular consumption of Brassica vegetables including cabbage, broccoli, cauliflower, Brussels sprouts and kale decrease the risk of various cancers ( Verhoeven et al., 1996 and Wu et al., 2009). The inverse association between consumption of Brassica vegetables and risk of cancer is mainly due to the presence of a unique family of secondary metabolites called glucosinolates ( Verhoeven et al., 1997 and Zhang and Talalay, 1994). Glucosinolates are characterised by a core sulfated isothiocyanate group, conjugated to β-thioglucose and a side-chain of diverse range (alkyl, aromatic, indole). To date approximately 200 distinct glucosinolates have been reported ( Clarke, 2010). Though glucosinolates themselves are not bioactive, during disruption of plant cells the coexisting enzyme myrosinase hydrolyses glucosinolates with a loss of glucose moiety to an unstable intermediate, which then further degrades to form various products, such as isothiocyanates, thiocyanates, nitriles, epithionitriles. Various degradation products act as anticancer agents by influencing phase I and phase II enzymes: for example the isothiocyanates sulforaphane and iberin, and indoles, such as indole-3-carbinol (I3C), ascorbigen (ABG) ( Ernst et al., 2013, van Poppel et al., 1999, Wagner and Rimbach, 2009 and Zhang and Talalay, 1994). Antimicrobial, antioxidant and anti-inflammatory activities of isothiocyanates and other sulphur compounds originating from Brassica vegetables have also been reported ( Kyung and Fleming, 1997, Lin et al., 2008 and Mastelić et al., 2010). However, some of the glucosinolate degradation products exhibit deleterious effects in the diet, especially the nitrile compounds such as indole-3-acetonitrile (I3A) ( Agerbirk, de Vos, Kim, & Jander, 2009).

The glucosinolate content in Brassica vegetables varies considerably with pre-harvest conditions such as soil type, fertiliser, light, temperature, and post-harvest conditions, like storage, cutting, blanching and cooking ( Verkerk et al., 2009). Post-harvest processing especially fermentation results in extended shelf life of the product and produces several potentially beneficial breakdown products. Among the fermented Brassica products, sauerkraut is a well-known traditional food made from shredded, brined white cabbage and it is commonly consumed in Europe. Ciska and Tolonen reported that fermentation results in complete degradation of glucosinolates and increased contents of health-promoting compounds, including sulforaphane, ABG and I3C ( Ciska and Pathak, 2004 and Tolonen et al., 2004). In addition, fermentation increased the antioxidant potential in Chinese Pak Choi ( Harbaum, Hubbermann, Zhu, & Schwarz, 2008), red cabbage ( Hunaefi, Akumo, & Smetanska, 2013) and white cabbage ( Kusznierewicz et al., 2008 and Peñas et al., 2012).

There are a few studies available about the effect of storage time and pasteurisation on glucosinolate content (Ciska and Honke, 2012, Ciska and Pathak, 2004 and Peñas et al., 2013). However, the influence of fermentation time on glucosinolates content has not yet been studied. Particularly, information is lacking on how glucosinolates are changed during the entire fermentation period starting from raw cabbage to sauerkraut. Therefore, specific analytical methods were developed in order to profile the changes in glucosinolates and glucobrassicin degradation products continuously from the beginning of fermentation until the end of storage. In addition, the change in microbiological content (lactic acid bacteria) has been closely monitored to see if there is a correlation between glucosinolate degradation and microbial population. The results obtained provide new insights on the importance of fermentation time to obtain health-promoting compounds and the importance of raw materials selection to obtain good end-products.

2. Materials and methods
2.1. Chemicals

Pottasium salt of glucobrassicin, glucoiberin, glucoraphanin were bought from PhytoLab GmbH &Co, KG (Vestenbergsgreuth, Germany). I3C, I3A and sinigrin hydrate were bought from Sigma–Aldrich. ABG was synthesised in our laboratories. Solvents were from Carl Roth GmbH & Co. KG (Karlsruhe, Germany).

2.2. Fermentation

White cabbage heads (Brassica oleracea L. var. capitata) cv. Storema RZ and cv. Lennox, which had been grown under standard conditions and harvested in October 2012, were donated by Rijk Zwann Company, Marne, Germany. Three cabbage heads were used from each cultivar, after removing core and outer layers, the cabbage heads were shredded into 2–3 mm thick slices using a food processor (Major Classic KM 800, Kenwood). The shredded plant material was mixed well with 0.9% salt and transferred into fermentation pots (150 mL glass containers with lid). The salted cabbage material was tightly pressed into the pots, pots were closed and placed into vacuum desiccators and kept under vacuum for 5 min to remove residual air. The pots were kept at 19–20 °C throughout fermentation and when a pH value of about 4.0 was reached (Day 9), the pots were stored in a refrigerator and continuously analysed.

2.3. Sampling

The fermentation experiment was carried out in 30 parallel pots, opening 3 pots at each sampling time. Sampling was done at Days 0, 2, 5, 7, 9, 14, 21, 28, 42 and 56; pH was measured immediately after opening the fermentation pots. Thereafter, fresh samples (containing cabbage strips with fermentation liquid) were taken for microbiological analysis and for extraction of volatiles and ABG content. Remaining samples were frozen with liquid nitrogen, dried in a freeze dryer, milled to fine powder and stored in a dessicator in the dark until glucosinolate analyses.

2.4. pH measurement and microbial analysis

The pH was measured directly from the fermentation pot containing shredded cabbage and juice by a pH meter (WTW Inolab IDS Multi 9420). Three fermentation pots were opened at each time point and each pot was measured three times.

For microbial analysis, five different media were applied for measuring growth by enumeration of colony-forming units (cfu) per g sauerkraut (drained weight). Total mesophilic, aerobic bacteria were determined on plate count (PC) agar, total lactic acid bacteria (LAB) on DeMan–Rogosa–Sharp (MRS) agar (De Man et al., 1960), peroxide-producing LAB on MRS agar supplemented with Prussian Blue (MRS-P) (Saito, Seki, Iida, Nakayama, & Yoshida, 2007), Enterobacteriaceae on violet red bile dextrose (VRBD) agar ( Mossel, Mengerink, & Scholts, 1962), and yeasts on yeast extract glucose chloramphenicol (YGC) agar. For each sample, 10 g of sauerkraut were filled into sterile stomacher bags and after mixing with 90 mL sterile Ringer’s solution homogenised for 1 min in a stomacher (Bagmixer 400; Interscience, St Nom, France) set at level 4. Appropriate decimal dilutions in ¼ strength Ringer’s solution were made and 0.1 mL of the dilutions were plated onto agar plates in duplicates. After aerobic incubation at 30 °C for 72 h (PC), 25 °C for 72 h (YGC), 37 °C for 24 h (VRBD), and anaerobic incubation at 30 °C for 72 h (MRS and MRS-PB), respectively, cfu were counted.

For 16S rDNA sequencing, genomic DNA was extracted from cell material of purified single colonies with the aid of the ZR Bacterial/Fungal DNA Mini Kit (ZymoResearch, Freiburg, Germany) following the protocol of the supplier. Using primers 16Suni_27F and 16Suni_1492R (Lane, 1991), 16S rDNA was amplified by polymerase chain reaction (PCR) as follows: (1) 98 °C for 3 min; (2) 98 °C for 10 s; (3) 53 °C for 30 s; (4) 72 °C for 90 s; (5) 72 °C for 10 min. After completion of the program, samples were stored at 4 °C. PCR products were purified by Nucleospin® gel and PCR clean-up (Macherey–Nagel, Düren, Germany) following the protocol of the supplier. DNA sequences were determined at Eurofins Genomics (Ebersberg, Germany) using the same primers as for PCR. DNA sequences were subjected to BlastN analyses at the NCBI web site for species identification (Altschul, Gish, Miller, Myers, & Lipman, 1990

Food Chemistry
Volume 190, 1 January 2016, Pages 755–762

Cover image
Influence of fermentation on glucosinolates and glucobrassicin degradation products in sauerkraut

Kalpana Palania, , , Britta Harbaum-Piaydaa, Diana Meskeb, Julia Katharina Kepplera, Wilhelm Bockelmannb, Knut J. Hellerb, Karin Schwarza
 Show more
doi:10.1016/j.foodchem.2015.06.012
Get rights and content
Highlights
•
The influence of fermentation time on glucosinolates (GLS) was monitored for the first time.
•
Fermentation leads to complete degradation of GLS and decreased content of indole-3-acetonitrile.
•
Fermentation increases ascorbigen and indole-3-carbinol content, and storage period decreases their content.
Abstract
A systematic investigation was carried out on the influence of fermentation on glucosinolates and their degradation products from fresh raw cabbage, throughout fermentation at 20 °C and storage at 4 °C. Glucosinolates were degraded dramatically between Day 2 and 5 of fermentation and by Day 7 there was no detectable amount of glucosinolates left. Fermentation led to formation of potential bioactive compounds ascorbigen (13.0 μmol/100 g FW) and indole-3-carbinol (4.52 μmol/100 g FW) with their higher concentrations from Day 5 to Day 9. However, during storage indole-3-carbinol slowly degraded to 0.68 μmol/100 g FW, while ascorbigen was relatively stable from Week 4 until Week 8 at 6.78 μmol/100 g FW. In contrast, the content of indole-3-acetonitrile decreased rapidly during fermentation from 3.6 to 0.14 μmol/100 g FW. The results imply a maximum of health beneficial compounds after fermentation (7–9 days) in contrast to raw cabbage or stored sauerkraut.

Keywords
Fermentation; White cabbage; Sauerkraut; Glucosinolates; Glucobrassicin degradation products; Ascorbigen; Indole-3-carbinol; Indole-3-acetonitrile; Bioactive compounds; Lactic acid bacteria
1. Introduction
Epidemiological studies have shown that regular consumption of Brassica vegetables including cabbage, broccoli, cauliflower, Brussels sprouts and kale decrease the risk of various cancers ( Verhoeven et al., 1996 and Wu et al., 2009). The inverse association between consumption of Brassica vegetables and risk of cancer is mainly due to the presence of a unique family of secondary metabolites called glucosinolates ( Verhoeven et al., 1997 and Zhang and Talalay, 1994). Glucosinolates are characterised by a core sulfated isothiocyanate group, conjugated to β-thioglucose and a side-chain of diverse range (alkyl, aromatic, indole). To date approximately 200 distinct glucosinolates have been reported ( Clarke, 2010). Though glucosinolates themselves are not bioactive, during disruption of plant cells the coexisting enzyme myrosinase hydrolyses glucosinolates with a loss of glucose moiety to an unstable intermediate, which then further degrades to form various products, such as isothiocyanates, thiocyanates, nitriles, epithionitriles. Various degradation products act as anticancer agents by influencing phase I and phase II enzymes: for example the isothiocyanates sulforaphane and iberin, and indoles, such as indole-3-carbinol (I3C), ascorbigen (ABG) ( Ernst et al., 2013, van Poppel et al., 1999, Wagner and Rimbach, 2009 and Zhang and Talalay, 1994). Antimicrobial, antioxidant and anti-inflammatory activities of isothiocyanates and other sulphur compounds originating from Brassica vegetables have also been reported ( Kyung and Fleming, 1997, Lin et al., 2008 and Mastelić et al., 2010). However, some of the glucosinolate degradation products exhibit deleterious effects in the diet, especially the nitrile compounds such as indole-3-acetonitrile (I3A) ( Agerbirk, de Vos, Kim, & Jander, 2009).

The glucosinolate content in Brassica vegetables varies considerably with pre-harvest conditions such as soil type, fertiliser, light, temperature, and post-harvest conditions, like storage, cutting, blanching and cooking ( Verkerk et al., 2009). Post-harvest processing especially fermentation results in extended shelf life of the product and produces several potentially beneficial breakdown products. Among the fermented Brassica products, sauerkraut is a well-known traditional food made from shredded, brined white cabbage and it is commonly consumed in Europe. Ciska and Tolonen reported that fermentation results in complete degradation of glucosinolates and increased contents of health-promoting compounds, including sulforaphane, ABG and I3C ( Ciska and Pathak, 2004 and Tolonen et al., 2004). In addition, fermentation increased the antioxidant potential in Chinese Pak Choi ( Harbaum, Hubbermann, Zhu, & Schwarz, 2008), red cabbage ( Hunaefi, Akumo, & Smetanska, 2013) and white cabbage ( Kusznierewicz et al., 2008 and Peñas et al., 2012).

There are a few studies available about the effect of storage time and pasteurisation on glucosinolate content (Ciska and Honke, 2012, Ciska and Pathak, 2004 and Peñas et al., 2013). However, the influence of fermentation time on glucosinolates content has not yet been studied. Particularly, information is lacking on how glucosinolates are changed during the entire fermentation period starting from raw cabbage to sauerkraut. Therefore, specific analytical methods were developed in order to profile the changes in glucosinolates and glucobrassicin degradation products continuously from the beginning of fermentation until the end of storage. In addition, the change in microbiological content (lactic acid bacteria) has been closely monitored to see if there is a correlation between glucosinolate degradation and microbial population. The results obtained provide new insights on the importance of fermentation time to obtain health-promoting compounds and the importance of raw materials selection to obtain good end-products.

2. Materials and methods
2.1. Chemicals

Pottasium salt of glucobrassicin, glucoiberin, glucoraphanin were bought from PhytoLab GmbH &Co, KG (Vestenbergsgreuth, Germany). I3C, I3A and sinigrin hydrate were bought from Sigma–Aldrich. ABG was synthesised in our laboratories. Solvents were from Carl Roth GmbH & Co. KG (Karlsruhe, Germany).

2.2. Fermentation

White cabbage heads (Brassica oleracea L. var. capitata) cv. Storema RZ and cv. Lennox, which had been grown under standard conditions and harvested in October 2012, were donated by Rijk Zwann Company, Marne, Germany. Three cabbage heads were used from each cultivar, after removing core and outer layers, the cabbage heads were shredded into 2–3 mm thick slices using a food processor (Major Classic KM 800, Kenwood). The shredded plant material was mixed well with 0.9% salt and transferred into fermentation pots (150 mL glass containers with lid). The salted cabbage material was tightly pressed into the pots, pots were closed and placed into vacuum desiccators and kept under vacuum for 5 min to remove residual air. The pots were kept at 19–20 °C throughout fermentation and when a pH value of about 4.0 was reached (Day 9), the pots were stored in a refrigerator and continuously analysed.

2.3. Sampling

The fermentation experiment was carried out in 30 parallel pots, opening 3 pots at each sampling time. Sampling was done at Days 0, 2, 5, 7, 9, 14, 21, 28, 42 and 56; pH was measured immediately after opening the fermentation pots. Thereafter, fresh samples (containing cabbage strips with fermentation liquid) were taken for microbiological analysis and for extraction of volatiles and ABG content. Remaining samples were frozen with liquid nitrogen, dried in a freeze dryer, milled to fine powder and stored in a dessicator in the dark until glucosinolate analyses.

2.4. pH measurement and microbial analysis

The pH was measured directly from the fermentation pot containing shredded cabbage and juice by a pH meter (WTW Inolab IDS Multi 9420). Three fermentation pots were opened at each time point and each pot was measured three times.

For microbial analysis, five different media were applied for measuring growth by enumeration of colony-forming units (cfu) per g sauerkraut (drained weight). Total mesophilic, aerobic bacteria were determined on plate count (PC) agar, total lactic acid bacteria (LAB) on DeMan–Rogosa–Sharp (MRS) agar (De Man et al., 1960), peroxide-producing LAB on MRS agar supplemented with Prussian Blue (MRS-P) (Saito, Seki, Iida, Nakayama, & Yoshida, 2007), Enterobacteriaceae on violet red bile dextrose (VRBD) agar ( Mossel, Mengerink, & Scholts, 1962), and yeasts on yeast extract glucose chloramphenicol (YGC) agar. For each sample, 10 g of sauerkraut were filled into sterile stomacher bags and after mixing with 90 mL sterile Ringer’s solution homogenised for 1 min in a stomacher (Bagmixer 400; Interscience, St Nom, France) set at level 4. Appropriate decimal dilutions in ¼ strength Ringer’s solution were made and 0.1 mL of the dilutions were plated onto agar plates in duplicates. After aerobic incubation at 30 °C for 72 h (PC), 25 °C for 72 h (YGC), 37 °C for 24 h (VRBD), and anaerobic incubation at 30 °C for 72 h (MRS and MRS-PB), respectively, cfu were counted.

For 16S rDNA sequencing, genomic DNA was extracted from cell material of purified single colonies with the aid of the ZR Bacterial/Fungal DNA Mini Kit (ZymoResearch, Freiburg, Germany) following the protocol of the supplier. Using primers 16Suni_27F and 16Suni_1492R (Lane, 1991), 16S rDNA was amplified by polymerase chain reaction (PCR) as follows: (1) 98 °C for 3 min; (2) 98 °C for 10 s; (3) 53 °C for 30 s; (4) 72 °C for 90 s; (5) 72 °C for 10 min. After completion of the program, samples were stored at 4 °C. PCR products were purified by Nucleospin® gel and PCR clean-up (Macherey–Nagel, Düren, Germany) following the protocol of the supplier. DNA sequences were determined at Eurofins Genomics (Ebersberg, Germany) using the same primers as for PCR. DNA sequences were subjected to BlastN analyses at the NCBI web site for species identification (Altschul, Gish, Miller, Myers, & Lipman, 1990

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เคมีอาหารปริมาณ 190, 1 2016 มกราคม หน้า 755-762 ภาพปกอิทธิพลของการหมักในผลิตภัณฑ์ย่อยสลาย glucosinolates และ glucobrassicin ใน sauerkrautKalpana Palania,,, Britta Harbaum Piaydaa, Diana Meskeb จูเลีย Katharina Kepplera วิลเฮล์ม Bockelmannb, Knut J. Hellerb คาริน Schwarza ดูเพิ่มเติมdoi:10.1016/j.foodchem.2015.06.012ได้รับสิทธิและเนื้อหาไฮไลท์•อิทธิพลของเวลาหมักใน glucosinolates (GLS) ถูกตรวจสอบเป็นครั้งแรก•หมักให้สมบูรณ์ของ GLS และลดเนื้อหาของอินโดล-3-acetonitrile•หมักเพิ่ม ascorbigen และเนื้อหาอินโดล-3-carbinol และระยะเวลาการจัดเก็บลดเนื้อหาบทคัดย่อตรวจสอบระบบได้ดำเนินการกับอิทธิพลของหมัก glucosinolates และผลิตภัณฑ์ย่อยสลายจากสดดิบกะหล่ำปลี หมักที่ 20 ° C และเก็บที่ 4 องศาเซลเซียส Glucosinolates ที่เสื่อมโทรมอย่างมากระหว่างวันที่ 2 และที่ 5 ของการหมัก และ โดย 7 วัน มีจำนวน glucosinolates ซ้ายไม่สามารถตรวจสอบได้ หมักที่นำไปสู่การกำเนิดของการเกิดสารประกอบกรรมการก ascorbigen (13.0 μmol/100 g FW) และอินโดล-3-carbinol (4.52 μmol/100 g FW) กับความเข้มข้นสูงของพวกเขาจาก 5 วันถึง 9 วัน อย่างไรก็ตาม ในระหว่างการเก็บอินโดล-3-carbinol ช้าลดลงเมื่อถึง 0.68 μmol/100 g FW, ascorbigen ที่ค่อนข้างมีเสถียรภาพจาก 4 สัปดาห์จนถึง 8 สัปดาห์ที่ 6.78 μmol/100 g FW ในทางตรงกันข้าม เนื้อหาของอินโดล-3-acetonitrile ลดลงอย่างรวดเร็วในระหว่างการหมักจาก 3.6 การ 0.14 μmol/100 g FW ผลลัพธ์เป็นสิทธิ์แบบสูงสุดของสารที่เป็นประโยชน์ต่อสุขภาพหลังหมัก (7-9 วัน) ตรงข้ามกะหล่ำปลีดิบหรือ sauerkraut เก็บไว้คำสำคัญหมัก กะหล่ำปลีสีขาว Sauerkraut Glucosinolates ผลิตภัณฑ์ย่อยสลาย Glucobrassicin Ascorbigen อินโดล-3-carbinol อินโดล-3-acetonitrile สารกรรมการก แบคทีเรียกรดแลกติก1. บทนำEpidemiological studies have shown that regular consumption of Brassica vegetables including cabbage, broccoli, cauliflower, Brussels sprouts and kale decrease the risk of various cancers ( Verhoeven et al., 1996 and Wu et al., 2009). The inverse association between consumption of Brassica vegetables and risk of cancer is mainly due to the presence of a unique family of secondary metabolites called glucosinolates ( Verhoeven et al., 1997 and Zhang and Talalay, 1994). Glucosinolates are characterised by a core sulfated isothiocyanate group, conjugated to β-thioglucose and a side-chain of diverse range (alkyl, aromatic, indole). To date approximately 200 distinct glucosinolates have been reported ( Clarke, 2010). Though glucosinolates themselves are not bioactive, during disruption of plant cells the coexisting enzyme myrosinase hydrolyses glucosinolates with a loss of glucose moiety to an unstable intermediate, which then further degrades to form various products, such as isothiocyanates, thiocyanates, nitriles, epithionitriles. Various degradation products act as anticancer agents by influencing phase I and phase II enzymes: for example the isothiocyanates sulforaphane and iberin, and indoles, such as indole-3-carbinol (I3C), ascorbigen (ABG) ( Ernst et al., 2013, van Poppel et al., 1999, Wagner and Rimbach, 2009 and Zhang and Talalay, 1994). Antimicrobial, antioxidant and anti-inflammatory activities of isothiocyanates and other sulphur compounds originating from Brassica vegetables have also been reported ( Kyung and Fleming, 1997, Lin et al., 2008 and Mastelić et al., 2010). However, some of the glucosinolate degradation products exhibit deleterious effects in the diet, especially the nitrile compounds such as indole-3-acetonitrile (I3A) ( Agerbirk, de Vos, Kim, & Jander, 2009).เนื้อหา glucosinolate ในผักผักไปจนมาก มีเงื่อนไขก่อนการเก็บเกี่ยวชนิดดิน fertiliser แสง อุณหภูมิ และสภาพหลังการเก็บเกี่ยว เช่นเก็บ ตัด blanching และทำอาหาร (Verkerk et al., 2009) หลังเก็บเกี่ยวแปรรูปหมักโดยเฉพาะอย่างยิ่งผลขยายอายุการเก็บรักษาผลิตภัณฑ์ และก่อให้เกิดประโยชน์อาจแบ่งหลายผลิตภัณฑ์ ในผลิตภัณฑ์ผักดอง sauerkraut เป็นอาหารดั้งเดิมรู้จักทำจากกะหล่ำปลีสีขาวที่หั่น brined และโดยทั่วไปได้ใช้ในยุโรป Ciska และ Tolonen รายงานว่า หมักผลย่อยสลายสมบูรณ์ glucosinolates และเนื้อหาที่เพิ่มขึ้นของการส่งเสริมสุขภาพสารประกอบ รวม sulforaphane, ABG และ I3C (Ciska และ Pathak, 2004 และ Tolonen et al., 2004) นอกจากนี้ หมักเพิ่มสารต้านอนุมูลอิสระมีศักยภาพในกะหล่ำปลีจีน Pak Choi (Harbaum, Hubbermann ซู & Schwarz, 2008), แดง (Hunaefi, Akumo, & Smetanska, 2013) และกะหล่ำปลีสีขาว (Kusznierewicz et al., 2008 และ Peñas et al., 2012)There are a few studies available about the effect of storage time and pasteurisation on glucosinolate content (Ciska and Honke, 2012, Ciska and Pathak, 2004 and Peñas et al., 2013). However, the influence of fermentation time on glucosinolates content has not yet been studied. Particularly, information is lacking on how glucosinolates are changed during the entire fermentation period starting from raw cabbage to sauerkraut. Therefore, specific analytical methods were developed in order to profile the changes in glucosinolates and glucobrassicin degradation products continuously from the beginning of fermentation until the end of storage. In addition, the change in microbiological content (lactic acid bacteria) has been closely monitored to see if there is a correlation between glucosinolate degradation and microbial population. The results obtained provide new insights on the importance of fermentation time to obtain health-promoting compounds and the importance of raw materials selection to obtain good end-products.2. Materials and methods2.1. ChemicalsPottasium salt of glucobrassicin, glucoiberin, glucoraphanin were bought from PhytoLab GmbH &Co, KG (Vestenbergsgreuth, Germany). I3C, I3A and sinigrin hydrate were bought from Sigma–Aldrich. ABG was synthesised in our laboratories. Solvents were from Carl Roth GmbH & Co. KG (Karlsruhe, Germany).2.2. FermentationWhite cabbage heads (Brassica oleracea L. var. capitata) cv. Storema RZ and cv. Lennox, which had been grown under standard conditions and harvested in October 2012, were donated by Rijk Zwann Company, Marne, Germany. Three cabbage heads were used from each cultivar, after removing core and outer layers, the cabbage heads were shredded into 2–3 mm thick slices using a food processor (Major Classic KM 800, Kenwood). The shredded plant material was mixed well with 0.9% salt and transferred into fermentation pots (150 mL glass containers with lid). The salted cabbage material was tightly pressed into the pots, pots were closed and placed into vacuum desiccators and kept under vacuum for 5 min to remove residual air. The pots were kept at 19–20 °C throughout fermentation and when a pH value of about 4.0 was reached (Day 9), the pots were stored in a refrigerator and continuously analysed.2.3. SamplingThe fermentation experiment was carried out in 30 parallel pots, opening 3 pots at each sampling time. Sampling was done at Days 0, 2, 5, 7, 9, 14, 21, 28, 42 and 56; pH was measured immediately after opening the fermentation pots. Thereafter, fresh samples (containing cabbage strips with fermentation liquid) were taken for microbiological analysis and for extraction of volatiles and ABG content. Remaining samples were frozen with liquid nitrogen, dried in a freeze dryer, milled to fine powder and stored in a dessicator in the dark until glucosinolate analyses.2.4. pH measurement and microbial analysisThe pH was measured directly from the fermentation pot containing shredded cabbage and juice by a pH meter (WTW Inolab IDS Multi 9420). Three fermentation pots were opened at each time point and each pot was measured three times.For microbial analysis, five different media were applied for measuring growth by enumeration of colony-forming units (cfu) per g sauerkraut (drained weight). Total mesophilic, aerobic bacteria were determined on plate count (PC) agar, total lactic acid bacteria (LAB) on DeMan–Rogosa–Sharp (MRS) agar (De Man et al., 1960), peroxide-producing LAB on MRS agar supplemented with Prussian Blue (MRS-P) (Saito, Seki, Iida, Nakayama, & Yoshida, 2007), Enterobacteriaceae on violet red bile dextrose (VRBD) agar ( Mossel, Mengerink, & Scholts, 1962), and yeasts on yeast extract glucose chloramphenicol (YGC) agar. For each sample, 10 g of sauerkraut were filled into sterile stomacher bags and after mixing with 90 mL sterile Ringer’s solution homogenised for 1 min in a stomacher (Bagmixer 400; Interscience, St Nom, France) set at level 4. Appropriate decimal dilutions in ¼ strength Ringer’s solution were made and 0.1 mL of the dilutions were plated onto agar plates in duplicates. After aerobic incubation at 30 °C for 72 h (PC), 25 °C for 72 h (YGC), 37 °C for 24 h (VRBD), and anaerobic incubation at 30 °C for 72 h (MRS and MRS-PB), respectively, cfu were counted.For 16S rDNA sequencing, genomic DNA was extracted from cell material of purified single colonies with the aid of the ZR Bacterial/Fungal DNA Mini Kit (ZymoResearch, Freiburg, Germany) following the protocol of the supplier. Using primers 16Suni_27F and 16Suni_1492R (Lane, 1991), 16S rDNA was amplified by polymerase chain reaction (PCR) as follows: (1) 98 °C for 3 min; (2) 98 °C for 10 s; (3) 53 °C for 30 s; (4) 72 °C for 90 s; (5) 72 °C for 10 min. After completion of the program, samples were stored at 4 °C. PCR products were purified by Nucleospin® gel and PCR clean-up (Macherey–Nagel, Düren, Germany) following the protocol of the supplier. DNA sequences were determined at Eurofins Genomics (Ebersberg, Germany) using the same primers as for PCR. DNA sequences were subjected to BlastN analyses at the NCBI web site for species identification (Altschul, Gish, Miller, Myers, & Lipman, 1990

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อาหารเคมีปริมาณ 190 , 1 มกราคม 2016 , หน้า 755 – 762

ภาพปก
อิทธิพลของกระบวนการหมักและย่อยสลายกลูโคซิโนเลต glucobrassicin ผลิตภัณฑ์ในกะหล่ำปลีดอง

kalpana palania , , , britta harbaum piaydaa ไดอาน่า meskeb จูเลีย katharina kepplera , วิลเฮล์ม bockelmannb Knut , เจ hellerb , คาริน schwarza

ดอย : แสดงเพิ่มเติม 10.1016 / j.foodchem . 2015.06.012
ได้รับสิทธิและเนื้อหา

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ไฮไลท์อิทธิพลของระยะเวลาในกลูโคซิโนเลต ( GLS ) คือการตรวจสอบครั้งแรกเลย . . .
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หมักสมบูรณ์และนำไปสู่การสลายตัวของ GLS ลดเนื้อหาของ indole-3-acetonitrile .
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ascorbigen หมักเพิ่ม และ indole-3-carbinol เนื้อหาและระยะเวลาในการเก็บลดลงเนื้อหา นามธรรม

การตรวจสอบระบบที่ดำเนินการเกี่ยวกับอิทธิพลของกระบวนการหมักและผลิตภัณฑ์จากการย่อยสลายของกลูโคซิโนเลท กะหล่ำดิบสดตลอดการหมักที่ 20 ° C และเก็บรักษาที่อุณหภูมิ 4 องศา กลูโคซิโนเลตกำลังเสื่อมโทรมอย่างมากระหว่างวันที่ 2 และ 5 ของการหมัก และ 7 วัน ไม่มีการตรวจพบปริมาณกลูโคซิโนเลตแล้วการหมักทำให้การพัฒนาศักยภาพของสารที่มีฤทธิ์ทางชีวภาพ ascorbigen ( ทั้งμโมลต่อ 100 กรัม FW ) และ indole-3-carbinol ( 4.52 μโมลต่อ 100 กรัม FW ) กับความเข้มข้นที่สูงขึ้นตั้งแต่วันที่ 5 ถึงวันที่ 9 อย่างไรก็ตาม ในระหว่างการเก็บรักษา indole-3-carbinol ช้าๆลง 0.68 μโมลต่อ 100 กรัม FW ในขณะที่ ascorbigen ค่อนข้างคงที่จากสัปดาห์ที่ 4 ถึงสัปดาห์ที่ 8 ที่ 6.78 μโมลต่อ 100 กรัม FW ในทางตรงกันข้าม

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