Nutritional content and health benefits of sun-dried and salt-aged radish (takuan-zuke)

A cooperative combination of non-targeted metabolomics and electronic tongue evaluation reveals the dynamic changes in metabolites and sensory quality of radish during pickling

Pickled radish is a traditional fermented food with a unique flavor after long-term preservation. This study analyzed the organoleptic and chemical characteristics of pickled radish from different years to investigate quality changes during pickling. The results showed that the sourness, saltiness, and aftertaste-bitterness increased after pickling, and bitterness and astringency decreased. The levels of free amino acids, soluble sugars, total phenols, and total flavonoids initially decreased during pickling but increased with prolonged pickling. The diversity of organic acids also increased over time. Through non-targeted metabolomics analysis, 349 differential metabolites causing metabolic changes were identified to affect the quality formation of pickled radish mainly through amino acid metabolism, phenylpropane biosynthesis and lipid metabolism. Correlation analysis showed that L*, soluble sugars, lactic acid, and acetic acid were strongly associated with taste quality. These findings provide a theoretical basis for standardizing and scaling up traditional pickled radish production.

Effects of different pickling methods on physicochemical properties and flavor profiles of Tongling white ginger: Dry-salting, brine-pickling, and inoculation-pickling

Tongling white ginger is a Chinese fermented vegetable with unique flavors. However, little is known about its physicochemical properties, flavor characteristics, and sensory evaluation. The study examined the physicochemical (pH, titratable acidity [TA], nitrite, soluble protein, and color) and flavor characteristics (organic acids, free amino acids, and volatiles) of white ginger during fermentation. The results showed that the pH value and soluble protein in the dry-salted, brine-pickled, and inoculation-pickled decreased significantly while the TA value increased significantly, inoculation-pickled can effectively reduce the content of nitrite. After fermentation, inoculation-pickled produced the highest content of organic acids, while dry-salted produced the highest total amount of free amino acids. A total of 70, 68, 70, and 69 volatile compounds were identified in fresh, dry-salted, brine-pickled, and inoculation-pickled white ginger. The total contents of terpenoids of Tongling white ginger by three fermentation methods decreased; the total contents of alcohols and aldehydes were the highest in brine-pickled, and esters and ketones were more abundant in inoculation-pickled. The results showed that inoculation-pickled could shorten the fermentation time of Tongling white ginger, produce a unique flavor, and have the highest sensory score.

Metabolomic profiling of the nutritional components of chicory leaves following heat processing

Chicory (Cichorium intybus L.; witloof) is a crisp bitter leafy vegetable, popularly used in western cuisine in salads and soups (leaves) and as an alternative to coffee (roasted roots). In this study, we explored the effect of heat processing under various temperatures and for different durations on the nutritional composition of chicory leaves using gas chromatography-mass spectrometry (GC/MS) and principal component analysis (PCA). "Vintor" chicory leaves were processed and homogenized to obtain lyophilized samples, and their moisture content and pH were measured. Heat processing was conducted at 4, 30, 60, and 100°C. Metabolites were extracted and analyzed using GC/MS. The results were statistically analyzed using multiple t-tests and Tukey-Kramer method. A PCA was conducted using standardized data. A lower temperature (≤60°C) positively influenced the concentrations of nutritional components (sugars, free amino acids, and organic acids), branched-chain amino acids (which reportedly improve exercise performance), and γ-aminobutyric acid (which exerts antihypertensive effects). Whereas, a higher temperature (100°C) and microwave processing induced the generation of low-molecular-weight sugars from polysaccharides and glycosides, decreased free amino acid concentrations, and caused heat-induced aminocarbonyl reactions. This study provides valuable information for enhancing the flavor profiles and potential health benefits of chicory leaves by identifying the optimal heat processing parameters for preserving the desired nutritional value. PRACTICAL APPLICATION: The palatability, nutritional content, and health benefits of chicory have been evaluated based on its inherent constituents, but changes in these parameters during food processing remain unclear. Heating at 30 and 60°C activated secondary metabolism in chicory, increasing the amino acid and organic acid concentrations, whereas heating at 100°C and microwave processing increased the sugar concentrations in chicory. Thus, the nutritional value and potential health benefits of chicory could be enhanced by processing it under controlled temperatures; the findings are valuable for both consumers and food processing industry.

Fermented Vegetables: Health Benefits, Defects, and Current Technological Solutions

This review summarizes current studies on fermented vegetables, analyzing the changes in nutritional components during pickling, the health benefits of fermented vegetables, and their safety concerns. Additionally, the review provides an overview of the applications of emergent non-thermal technologies for addressing these safety concerns during the production and processing of fermented vegetables. It was found that vitamin C would commonly be lost, the soluble protein would degrade into free amino acids, new nutrient compositions would be produced, and the flavor correlated with the chemical changes. These changes would be influenced by the variety/location of raw materials, the original bacterial population, starter cultures, fermentation conditions, seasoning additions, and post-fermentation processing. Consuming fermented vegetables benefits human health, including antibacterial effects, regulating intestinal bacterial populations, and promoting health (anti-cancer effects, anti-diabetes effects, and immune regulation). However, fermented vegetables have chemical and biological safety concerns, such as biogenic amines and the formation of nitrites, as well as the existence of pathogenic microorganisms. To reduce hazardous components and control the quality of fermented vegetables, unique starter cultures, high pressure, ultrasound, cold plasma, photodynamic, and other technologies can be used to solve these problems.

Potential role of cell wall pectin polysaccharides, water state, and cellular structure on twice "increase-decrease" texture changes during kohlrabi pickling process

Pickled kohlrabi is a traditional and favored vegetable product in China. During pickling, the hardness, springiness, and chewiness of kohlrabi all experienced a typical change with twice "increase-decrease" trend. However, little is known about its mechanism. In this study, in situ analysis including immunofluorescence, low field nuclear magnetic, and transmission electron microscopy were used to explore the effects of cell wall pectin, water state, and cellular structure on kohlrabi texture changes during pickling. Results revealed that at the early stage, due to the rapid loss of water after three times salting, the cells shrank and the interstitial space reduced, resulting in the first increase on kohlrabi texture. Subsequently, the dehydration-rehydration caused by the first brine processing resulted in the first decrease on kohlrabi texture. Then under the action of PME enzyme, more low-esterified pectin was produced, and chelate-soluble pectin with more branched structure was further formed, leading to another elevation of the sample texture. As the pickling continued, under the combined action of PG and PME, the molecular weight of pectin was decreased and the rigidity of the cell tissue was destroyed, caused kohlrabi texture continued to decline. These researches could provide important information and guidance for better maintaining the texture of pickled vegetables during processing.

Stereoselective behaviors and enantiomeric effects of paclobutrazol on microorganisms during Chinese cabbage pickling process

Studies on the differences between chiral pesticide enantiomers have caused widespread concern in the last decade. In the current work, the selective behaviors and different biological activities of paclobutrazol enantiomers during Chinese cabbage pickling process were evaluated. Results of degradation kinetics indicated that when paclobutrazol reside in raw material (Chinese cabbage) and was introduced into the pickling process, the degradation rates of the two paclobutrazol enantiomers were significantly different, the half-lives of (2R, 3R)-paclobutrazol (R-paclobutrazol) and (2S, 3S)-paclobutrazol (S-paclobutrazol) were 18.24 and 6.19 d, respectively. Besides, the conversion between the two enantiomers could also be observed, and the conversion rate of R-paclobutrazol to S-paclobutrazol was slower than that of reverse process. In addition, from the analysis of 16S rRNA and ITS sequencing, we inferred that the degradation of paclobutrazol was probably due to the presence of Pseudomonas and Serratia. Moreover, there has a significant difference in biological activity between R-paclobutrazol and S-paclobutrazol and shown an obviously enantiomeric effects on microbial community composition of pickling system. Besides, the analysis of microbial community displayed R-paclobutrazol might inhibit the growth of Erwinia (a sort of plant pathogens). Results from this study served to enhance our understanding of chiral pesticide residues on food safety and the potential risks to human health.

Improvement of physicochemical characteristics, flavor profiles and functional properties in Chinese radishes via spontaneous fermentation after drying

Spontaneously dried-fermented radishes have been consumed in China for hundreds of years and are usually fermented for a long time to acquire high quality. In this study, the spontaneously dried-fermented radishes with short-term manufacturing periods were made from five different varieties of radishes that grew in the same environment. In addition, the physicochemical characteristics (i.e., moisture content, soluble solid, and pH value), flavor profiles (i.e., free amino acids, organic acids, and volatile compounds), and functional properties (i.e., total phenolics content, total flavonoids content, sulforaphane content, and γ-aminobutyric acid [GABA] content) of these five raw radishes and spontaneously dried-fermented radishes were analyzed and compared. In detail, the content of volatile and nonvolatile compounds increased, especially in oxalic acid, succinic acid, and umami free amino acids. Furthermore, functional components, such as sulforaphane and GABA, were also enriched via spontaneous fermentation after drying. In addition, the results of principal component analysis, hierarchical clustering analysis, and redundancy analysis showed that there were significant discrepancies appeared when raw radishes were processed via spontaneous fermentation or not. These results suggested that the process of spontaneous fermentation after drying may contribute to improving the quality of fresh radishes. Notably, radishes with red skin and flesh were regarded as exceptional varieties for processing, because of the preferable flavor profiles and affluent functional substances via spontaneous fermentation after drying. Therefore, these findings could deliver a systematical insight into developing processed radishes with high quality. PRACTICAL APPLICATION: The spontaneously dried-fermented radishes were manufactured through the process of spontaneous fermentation after drying, which acquired tasty and healthy characteristics by accumulating the volatile and nonvolatile compounds as well as the functional components, like total phenolics, total flavonoids, sulforaphane, and γ-aminobutyric acid. Importantly, because of the excellent processing properties, the radishes with red skin and flesh could be more appropriate to produce spontaneously dried-fermented radishes. Our findings may provide a practical strategy for developing vegetable relishes with superb flavor profiles and good functional properties in pickled vegetables.

Production of Marinated Chinese Lotus Root Slices Using High-Pressure Processing as an Alternative to Traditional Thermal-and-Soaking Procedure

Marinated vegetables are traditional cold dishes with a long history and special flavor in the Chinese deli market. However, the traditional thermal-and-soaking (TS) procedure often results in unreproducible flavor quality properties of marinated vegetables and waste of brine and time in production. A novel green and sustainable technique, high-pressure processing (HPP), has caught the attention of the food industry. In this study, the effects of HPP and TS treatment on the visual, flavor, textural, and microbiological qualities of Chinese marinated lotus root slices were investigated. Compared to the TS products, lighter color, more varieties of volatile compounds, and crunchier texture were detected in the HPP products. Throughout the 4 °C, 25 °C, and 45 °C shelf life challenges, the HPP products retained their original color and crunchiness better than the TS ones, whereas no significant differences were found in total viable counts (TVCs) in the first half of the shelf lives. The Arrhenius model under the first-order reaction of TVC deterioration showed a good fit to the shelf life of the HPP marinated lotus root slices. This study demonstrates that HPP may assist in making the best use of brine in a more time-efficient manner to improve the visual, flavor, and textural quality of traditional Chinese marinated lotus root slices.

Nutritional Content Dynamics and Correlation of Bacterial Communities and Metabolites in Fermented Pickled Radishes Supplemented With Wheat Bran

Wheat bran supplementation in cereal food processing improves the nutritional value and quality of the final products. However, whether wheat bran has the potential as a biofortifier to enhance nutritional and flavor of fermented vegetables remains unknown. The study aimed to evaluate the potential of wheat bran supplementation for nutrition and flavor fortification during radish fermentation, and to explore the role of microorganisms in nutritional and flavor development. Using high-throughput sequencing coupled with high-performance liquid chromatography and headspace solid-phase microextraction-gas chromatography-mass spectrometry, the microbial community profiles and nutritional and flavor changes of wheat bran-treated samples were analyzed and compared with control samples. Correlation analysis between bacteria taxa with metabolites were also performed. The results showed that wheat bran treatment increased the content of most free amino acids (FAAs), α-linolenate, thiamine, and riboflavin in the samples (p < 0.05). In addition, the increased consumption of reducing sugar and glutamate in the wheat bran-treated samples was due to the production of secondary metabolites such as lactic acid, ethanol, acetic acid, and GABA (p < 0.05). Moreover, compared with control samples, the flavor of the wheat bran-treated pickled radish was preferable. Wheat bran increased the amount of alcohol, ester, acid, and ketones compounds but reduced the number of sulfides, which increased the aroma but decreased the pungent flavor. Additionally, the correlation analysis suggested that Lactobacillus, the most dominant genus, was boosted by wheat bran and was positively associated with most of FAAs, GABA, and lactate, while negatively associated with most sulfides. Therefore, compared with the control, wheat bran treatment could improve the nutritional values and sensorial properties of radish pickles. New areas of research should explore the co-fermentation of other vegetables with wheat bran, and the potential of this processing technique to provide consumers with products of high nutritional quality.

Branched-chain amino acid synthesis and glucosinolate-myrosinase system during takuan-zuke processing of radish root

The traditional Japanese fermented pickle, takuan-zuke, is produced via dehydration and salt-aging of the Japanese winter radish root (Raphanus sativus L.). It has been reported that γ-aminobutyric acid (GABA; antihypertensive factor) accumulates during this production. Herein, the results of the comprehensive study (metabolites, enzyme activity, and gene expression levels were investigated) on the mechanism of branched-chain amino acid (BCAA) synthesis and glucosinolate (GLS)-myrosinase system of daikon dehydration have been reported. BCAAs, GLS, and their precursors were temporarily upregulated, and the genes linked to BCAA, GLS, and isothiocyanate synthesis (BCAT4, MAM3, IPMDH1, RMB1, RMB2, and GRS1) were upregulated during daikon dehydration. BCAAs and GLS accumulated in daikon during dehydration owing to the upregulation of genes, encoding these synthases as a stress response. These results suggest that the biological response of daikon adds characteristic flavor and health functionality to takuan-zuke and helps optimize the processing parameters to produce pickles with improved health benefits. PRACTICAL APPLICATIONS: Takuan-zuke is a popular pickle in Japan, which is produced from a Japanese winter radish root (Raphanus sativus L.), commonly referred to as daikon in Japan. Takuan-zuke is produced by dehydrating daikon either by the process of salt-pressing (shio-oshi) or sun-drying (hoshi). The processes influence the variations in the nutritional value of the final product. The results reveal that both the daikon dehydration processes can be followed to generate increased amounts of health-promoting components (e.g., branched-chain amino acid and glucosinolate) in takuan-zuke.

Three Novel Dietary Phenolic Compounds from Pickled Raphanus Sativus L. Inhibit Lipid Accumulation in Obese Mice by Modulating the Gut Microbiota Composition

SCOPE

Although pickled radish is widely consumed worldwide, few studies have investigated the nutritional benefits of bioactive compounds extracted from pickled radish. In this study, the authors investigate the relationship among dietary phenolic compounds, lipid accumulation, and gut microbiota.

METHOD AND RESULTS

Three phenolic compounds 2,6-dihydroxyacetophenone (DHAP), 4-hydroxyphenethyl alcohol (4-HPEA), and 4-hydroxybenzaldehyde (HBA) are extracted from pickled radish. LO2 cells treated with free fatty acid are first used to explore the impact of the above three compounds at different doses on reducing lipid levels. The effects of the three compounds on obesity and the gut microbiota are further investigated in high-fat diet (HFD)-induced KM mice. Results show that three compounds inhibited the lipid accumulation in LO2 cells. The results of animal experiments reveal that three compounds prevented body weight gain and significantly decreased serum lipid levels. Treatment with DHAP, HPEA, and HBA reversed gut microbiome dysbiosis in HFD-induced mice. The three phenolic compounds increase Odoribacter, and decrease Helicobacter and Mucispirillum. Notably, DHAP and HBA reduce the HFD-induced increase in the Firmicutes/Bacteroidetes ratio.

CONCLUSION

These data suggest that phenolic compounds extracted from pickled radish possess excellent lipid-lowering capacity, providing a theoretical basis for further analysis of the nutritional value of pickled radish.

Metabolism of glutamic acid to alanine, proline, and γ-aminobutyric acid during takuan-zuke processing of radish root

Takuan-zuke is a traditional Japanese fermented pickle, prepared by dehydration of radish root (daikon) by salt-pressing or sun-drying followed by aging with salt. We previously reported that alanine, proline, and γ-aminobutyric acid (GABA) accumulate during daikon dehydration, whereas the level of glutamic acid, their precursor, decreases. We have also reported that dehydration and salt-aging markedly influence the dynamics of free amino acids. In this study, we quantitatively analyzed free amino acid levels, enzyme activity, and gene expression to characterize takuan-zuke amino acid metabolism. Enzyme activities related to alanine, proline, GABA, and glutamic acid metabolism were sustained during dehydration. Moreover, genes encoding alanine, proline, and GABA synthases (ALT1, P5CS1, and GAD4) were significantly upregulated during dehydration. These effects may represent cellular stress responses to the dehydration process. The biological response of daikon contributes to the healthy functional aspects that characterize takuan-zuke. These findings could guide the selection of suitable vegetable varieties to produce pickled vegetables with health-promoting properties. PRACTICAL APPLICATION: The fermented pickle takuan-zuke, prepared by dehydration of radish root (daikon), accumulates amino acids, such as alanine, proline, and GABA, during preparation that provide taste and health benefits. In this study, the aforementioned amino acids were found to accumulate because of the stress response of daikon during the dehydration process and not because of the action of microorganisms during fermentation. Takuan-zuke processing is a method for improving the nutrition of daikon.

Salted and Unsalted Zhàcài (Brassica juncea var. tumida) Alleviated High-Fat Diet-Induced Dyslipidemia by Regulating Gut Microbiota: A Multiomics Study

SCOPE

Zhàcài (ZC), a salting-processed Brassica juncea var. tumida vegetable, is widely consumed as a pickle, but little is known about the health benefits of both salted and unsalted ZC as a whole food.

METHODS AND RESULTS

The preventive effects of salted and unsalted ZC against dyslipidemia are assessed in high-fat (HF) diet-fed mice. HF intake for 12 continuous weeks cause dyslipidemia in mice, as evidenced by the elevations in serum total triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels by 30%, 66%, and 117%, respectively. Metabolomics analysis and the 16S rRNA genes sequencing suggest that dietary administration of salted and unsalted ZC (2.5% w/w) alleviates HF-induced dyslipidemia, metabolic disorders of short-chain fatty acids, and disturbance of intestinal flora in mice. These positive effects of unsalted ZC are stronger than those of salted ZC. Moreover, fecal bacteria transplantation confirms the antidyslipidemia of ZC.

CONCLUSION

These results suggest that consumption of ZC may prevent HF-induced dyslipidemia by regulating gut microbiota.

Effects of calcium chloride plus coating in modified-atmosphere packaging storage on whole-radish postharvest quality

BACKGROUND

Calcium treatment plays an important role in regulative physiological functions in fruits and vegetables after harvest that is protected many horticulture products postharvest quality during storage life. The effects of 2% calcium chloride (CaCl₂ ) and 1% starch + 2% glycerin on the physiological, biochemical, and quality responses of the Kadirli radish variety were investigated.

RESULTS

Whole leafless radishes were stored in 10 kg modified-atmosphere packages at 90% relative humidity conditions at 4 °C for 56 days. Significant differences were observed in radish treated with 2% CaCl₂ and coating with 1% starch + 2% glycerin compared with the control. There were significant effects of the application of CaCl₂ either alone or in combination with a coating on radish with regard to the firmness and the important physiological disorder of hollowing ratio percentage and cell membrane (malondialdehyde) aging level of the fresh whole radish.

CONCLUSION

The application of CaCl₂ alone and in combination with coating protected the physical, chemical, and microbiological quality characteristics of radish and prolonged the shelf-life quality of fresh radish. © 2020 Society of Chemical Industry.

Extraction and characterization of phenolic compounds with antioxidant and antimicrobial activities from pickled radish

The pickled radish can be kept at room temperature for years without spoilage. 2,6-dihydroxyacetophenone (DHAP), 4-hydroxybenzaldehyde (HBA), and 4-hydroxyphenethyl alcohol (4-HPEA) were first found from the pickled radish. The structures of three phenolic compounds were elucidated by analysis of their nuclear magnetic resonance and high-resolution electro-spray ionization mass spectrometry data. All these phenolic compounds showed good free radical scavenging capacity except HBA. Both DHAP and 4-HPEA also showed high ferric reducing ability. DHAP showed good antimicrobial activity against Escherichia coli, Bacillus subtilis, and Canidia albicans. HBA demonstrated antimicrobial activity against E. coli and C. albicans but not B. subtilis. Based on the results of MTT assay, these compounds did not show cytotoxicity to LO2 cell line. All results indicated the pickled radish had antioxidant and antimicrobial phenolic compounds. To the best of our knowledge, this report is the first to answer partially the question of why pickled foods can be kept at room temperature for years without spoilage based on the evidence of three phenolic compounds.

Deciphering the Nutraceutical Potential of Raphanus sativus-A Comprehensive Overview

Raphanus sativus (Radish) belongs to the Brassicaceae family and is a widely consumed root vegetable all around the world. The nutritional and medicinal values of radishes have been proven by several researches. Extracts prepared from the aerial and underground parts of radishes have been used in the treatment of stomach disorders, urinary infections, hepatic inflammation, cardiac disorders and ulcers in folk medicine since the ancient times. The pharmaceutical potential of radishes is attributed to the presence of its beneficial secondary metabolites, such as glucosinolates, polyphenols and isothiocyanates. The present review has focused on the impact of radish extract administration under pathological complications, such as cancer, diabetes, hepatic inflammation and oxidative stress. In addition, a comprehensive view of molecular mechanism behind the regulation of molecular drug targets associated with different types of cancers and diabetes by the bioactive compounds present in the radish extracts have been discussed in detail.

The salted radish takuan-zuke shows antihypertension effects in spontaneously hypertensive rats

Recently, we reported that the antihypertensive compound, γ-aminobutyrate (GABA), increases over time during the dehydration of salted radish, known as takuan-zuke, a popular pickle in Japan.