Integrated Mechanism of Immune Response Modulation by Arctium Lappa L. Fructans Based on Microbiome and Metabolomics Technologies.

Arctium lappa L. is widely consumed for its various biological effects, and polysaccharides are its main functional components. The present study aimed to evaluate the immunoregulatory effects of the main polysaccharides from burdock (ALP-1) and reveal the underlying mechanisms. ALP-1 consisted of fructose and glucose (14.57:1) and had a molecular weight of 2757 Da, with typical characteristics of (1 → 2)-linked linear fructans. Oral intake of ALP-1 significantly increased the number of colonic goblet cells, serum immunoglobulin A and immunoglobulin G levels, and fecal secretory immunoglobulin A content as well as up-regulated antioxidant enzymes and increased short chain fatty acid production. In addition, ALP-1 administration regulated pro/anti-inflammatory cytokines (i.e., interleukin (IL)-1ß, IL-6, tumor necrosis factor-α, interferon-γ, and IL-10), intestinal microbiota structure, and the spatial information on key metabolites. Some gut-microbiota-mediated metabolic processes were also significantly altered. These results indicated that ALP-1 could exert beneficial effects on immune responses and intestinal health in healthy mice.

Physicochemical, Structural, and Functional Properties of Fructans from Single-Clove Garlic and Multiclove Garlic: A Comparison.

This study aimed to compare the structural features and functional properties of polysaccharides from single-clove garlic (SGPs) and multiclove garlic (MGPs) and to establish their structure-function relationships. Both SGPs and MGPs were identified as fructans consisting mainly of →1)-ß-d-Fruf (2→ and →6)-ß-d-Fruf (2→ residues but differed in average molecular weights (6.76 and 5.40 kDa, respectively). They shared similar thermodynamic properties, X-ray diffraction patterns, and high gastrointestinal digestive stability. These two purified fructans could dose-dependently scavenge free radicals, reduce oxidized metals, and effectively alleviate metronidazole-induced oxidative stress and CuSO4-induced inflammation in zebrafish via inhibiting the overexpression of inflammation-related proteins and cytokines. SGPs showed lower free radical scavenging activity in vitro than MGPs but higher antioxidant and anti-inflammatory activities in vivo. Taken together, the molecular weight was the main structural difference between the two garlic fructans of different varieties, which is a potential reason for their differences in biological activities.

Fabrication of caffeoylquinic acid-loaded burdock polysaccharide nanoparticles and their antioxidant activity in hydrogen peroxide-damaged HepaRG cells.

Herein, burdock polysaccharide (BP) and modified burdock polysaccharide (MBP) were prepared, followed by the fabrication of chlorogenic acid (CA)-BP, CA-MBP, isochlorogenic acid A (ICA)-BP, and ICA-MBP nanoparticles. Afterward, the structural characteristics, physical stability, digestive characteristics, and antioxidant activity of hydrogen peroxide (H2O2)-damaged HepaRG cells were evaluated. The result indicated that the loading capacities of CA in BP-CA and MBP-CA were 0.14 and 0.53 µg/mg, respectively. Conversely, the loading capacities of ICA in BP-ICA and MBP-ICA were 0.36 and 0.60 µg/mg, respectively. Four complex nanoparticles exhibited excellent physical stability under different pH values, temperatures, and ionic concentrations, especially MBP-CA and MBP-ICA. Moreover, four complex nanoparticles could protect caffeoylquinic acid from being released in gastric fluid. All six samples exhibited high antioxidant activity in H2O2-induced HepaRG cells, especially BP and MBP-CA. These findings indicated that caffeoylquinic acid-polysaccharide complexes were successfully prepared and highlighted the potential of polysaccharides as natural carriers for hydrophobic bioactive molecules.

Quality Improvement of Garlic Paste by Whey Protein Isolate Combined with High Hydrostatic Pressure Treatment.

Garlic, one of the most popular spices and medical herbs, has a unique pungent flavor and taste. Conventional homogenization and thermal treatment commonly lead to flavor and color deterioration in garlic paste, because allicin is highly susceptible to degradation and reaction. The present study was to investigate the effects of whey protein isolate (WPI) and different levels of high hydrostatic pressure (HHP, 200, 300, 400, 500, and 600 MPa) on the quality of garlic paste. Results showed that the addition of WPI in the homogenization of garlic significantly prevented green discoloration. Furthermore, WPI plus HHP under 500 MPa could better protect the color of garlic paste. Higher pressure (600 MPa) led to WPI aggregation, resulting in higher green color chroma of garlic paste. GC-MS results revealed that the application of WPI and HHP in garlic paste increased the relative level of pungent flavor compounds and decreased those of unpleasant odor compounds. The correlation analysis results revealed that WPI efficiently prevented garlic green discoloration, which is attributed to the thiol group in WPI exchanging the sulfonyl groups in allicin. In consideration of the microbial load, flavor and color quality of garlic paste, the optimal processing conditions were found at 500 MPa for 5 min with 2% WPI addition, extending shelf life to 25 days.

Garlic polysaccharide-Cr (III) complexes with enhanced in vitro and in vivo hypoglycemic activities.

This study aimed to prepare a complex of Cr (III) and garlic polysaccharides (GPs) and evaluate the in vitro and in vivo hypoglycemic activities of GPs and GP-Cr (III) complexes. The chelation of GPs with Cr (III) increased molecular weight, modified crystallinity, and altered morphological characteristics, through targeting the OH of hydroxyl groups and involving the C-O/O-C-O structure. The GP-Cr (III) complex had a higher thermal stability over 170-260 °C and higher stability throughout the gastrointestinal digestion. In vitro, the GP-Cr (III) complex exhibited a significantly stronger inhibitory effect against α-glucosidase compared with the GP. In vivo, the GP-Cr (III) complex at a high dose (4.0 mg Cr/kg body weight) generally had a higher hypoglycemic activity than the GP in (pre)-diabetic mice induced by a high-fat and high-fructose diet, based on indices like body weight, blood glucose levels, glucose tolerance, insulin resistance, insulin sensitivity, blood lipid levels, and hepatic morphology and function. Therefore, GP-Cr (III) complexes could be a potential Cr (III) supplement with an enhanced hypoglycemic activity.

Advancement and prospects of production, transport, functional activity and structure-activity relationship of food-derived angiotensin converting enzyme (ACE) inhibitory peptides.

Food-derived antihypertensive peptides have attracted increasing attention in functional foods for health promotion, due to their high biological activity, low toxicity and easy metabolism in the human body. Angiotensin converting enzyme (ACE) is a key enzyme that causes the increase in blood pressure in mammals. However, few reviews have summarized the current understanding of ACE inhibitory peptides and their knowledge gaps. This paper focuses on the food origins and production methods of ACE inhibitory peptides. Compared with conventional methods, the advanced technologies and emerging bioinformatics approaches have recently been applied for efficient and targeted release of ACE inhibitory peptides from food proteins. Furthermore, the transport and underlying mechanisms of ACE inhibitory peptides are emphatically described. Molecular modeling and the Michaelis-Menten equation can provide information on how ACE inhibitors function. Finally, we discuss the structure-activity relationships and other bio-functional properties of ACE inhibitory peptides. Molecular weight, hydrophobic amino acid residues, charge, amino acid composition and sequence (especially at the C-terminal and N-terminal) have a significant influence on ACE inhibitory activity. Some studies are required to increase productivity, improve bioavailability of peptides, evaluate their bio-accessibility and efficiency on reducing blood pressure to provide a reference for the development and application of health products and auxiliary treatment drugs.

Preparation and Characterization of Ginger Peel Polysaccharide-Zn (II) Complexes and Evaluation of Anti-Inflammatory Activity.

The present study aimed to explore the improvement of the bioactivity of ginger peel polysaccharides (GPs) by the modification of zinc after structural characterization. The obtained GP-Zn (II) complexes consisted dominantly of glucose and galactose in a mass proportion of 95.10:2.10, with a molecular weight of 4.90 × 105 Da and a Zn content of 21.17 mg/g. The chelation of GPs and Zn (II) was mainly involved in the O-H of hydroxyl groups, and this interaction reduced the crystallinity and decreased the asymmetry of GPs, with a slight effect on the thermal stability. The administration of GPs and their Zn (II) complexes effectively alleviated CuSO4-induced inflammatory response in zebrafish (Tg: zlyz-EGFP) via down-regulating the mRNA expression levels of pro-inflammatory cytokines (IL-1ß, IL-6, IL-8, IL-12 and TNF-α) and upregulating the expression of anti-inflammatory cytokine (IL-10). Furthermore, the modification of Zn (II) enhanced the inflammation-inhibiting effect of polysaccharides. Therefore, GP-Zn (II) complexes could be applied as a candidate anti-inflammatory agent for the treatment of chronic inflammation-related diseases.

Visualizing the Spatial Distribution of Arctium lappa L. Root Components by MALDI-TOF Mass Spectrometry Imaging.

This study is aimed at developing novel analytical methods to accurately visualize the spatial distribution of various endogenous components in Arctium lappa L. (A. lappa) roots, and to precisely guide the setting of pre-treatment operations during processing technologies and understand plant metabolism process. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) imaging technology was used for visual demonstration of the in situ spatial distribution in A. lappa roots. This work consisted of four steps: matrix selection, section preparation, matrix coating, and MALDI-TOF MS imaging analysis. Consequently, eight saccharides, four caffeoylquinic acids, four flavonoids, six amino acids, one choline, and one phospholipid were imaged and four unidentified components were found. Saccharides were distributed in the center, whereas caffeoylquinic acids and flavonoids were mainly present in the epidermis and cortex. Furthermore, amino acids were mainly detected in the phloem, and choline in the cambium, while phosphatidylserine was found in the secondary phloem and cambium. This study demonstrated that MALDI-TOF MS imaging technology could provide a technical support to understand the spatial distribution of components in A. lappa roots, which would promote the processing technologies for A. lappa roots and help us to understand the plant metabolism process.

Digestive properties and prebiotic activity of garlic saccharides with different-molecular-weight obtained by acidolysis.

Garlic saccharides have prebiotic activity, but the association between their function and structure is still poorly known. In present study, four different garlic saccharides were obtained from garlic polysaccharides (GPs) after acidolysis by ultrafiltration. Obtained GPs were constituted by different monosaccharides, among which fructose and glucose were the main components, while galactose was a major component of GPs-U6. All four saccharides were partly degraded by the simulated digestive system, and most could reach the large intestine to be utilized by the gut microbiota. Except for GPs-U6, the other three garlic saccharide fractions had good prebiotic activity in vitro and in vivo. Furthermore, GPs-U0.3 with lower molecular weight (Mw) showed better prebiotic activity, including promoting the production of short-chain fatty acids (SCFAs), increasing the abundance of beneficial bacteria such as Bifidobacterium, Lachnospiraceae NK4A136 group and Phoscolarctobacterium, and inhibiting the growth of potentially harmful bacteria. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway enrichment analysis showed that GPs-U0.3 could reduce the risk of cancer and cardiovascular diseases. Overall, this findings of the present study revealed the digestive properties of GPs, as well as the potential association between their chemical structures and fermentation characteristics by gut microbiota. Thus, it can be stated that GPs-U0.3 can be used as potential prebiotics in functional foods, which provides a theoretical basis for the targeted preparation of functionalized garlic saccharides.

Preparation and characterization of garlic polysaccharide-Zn (II) complexes and their bioactivities as a zinc supplement in Zn-deficient mice.

This study explored the potential of garlic polysaccharides (GPs) as a carrier for synthesizing GP-Zn (II) complexes to supplement Zn. According to the response surface analysis, the optimal preparation conditions were: mass ratio of GPs to Zn2+ 1:0.21, temperature 53 °C, pH 5.9 and time 148.75 min, with the maximum chelation rate of 90.11%. The chelation of GPs and Zn2+ involved O-H/C-O/O-C-O groups, increased crystallinity and altered absorption peaks of circular dichroism spectra, with a higher thermal stability, particle size and negative zeta potential. Compared with inorganic zinc salts, supplementation of GP-Zn (II) complexes showed enhance zinc supplementation effects in Zn-deficient mice model: increased body weight, organ index and Zn (II) levels in serum and liver, enhanced Superoxidedismutase (SOD) activity and alkaline phosphatase activity, decreased NO content and Malondialdehyde (MDA) content and improved colon and testicular morphology. Therefore, GP-Zn (II) complex can be used as a potential zinc supplement for Zn-deficient individuals.

Bioactive polysaccharides and oligosaccharides from garlic (Allium sativum L.): Production, physicochemical and biological properties, and structure-function relationships.

Garlic is a common food, and many of its biological functions are attributed to its components including functional carbohydrates. Garlic polysaccharides and oligosaccharides as main components are understudied but have future value due to the growing demand for bioactive polysaccharides/oligosaccharides from natural sources. Garlic polysaccharides have molecular weights of 1 × 103 to 2 × 106  Da, containing small amounts of pectins and fructooligosaccharides and large amounts of inulin-type fructans ((2→1)-linked ß-d-Fruf backbones alone or with attached (2→6)-linked ß-d-Fruf branched chains). This article provides a detailed review of research progress and identifies knowledge gaps in extraction, production, composition, molecular characteristics, structural features, physicochemical properties, bioactivities, and structure-function relationships of garlic polysaccharides/oligosaccharides. Whether the extraction processes, synthesis approaches, and modification methods established for other non-garlic polysaccharides are also effective for garlic polysaccharides/oligosaccharides (to preserve their desired molecular structures and bioactivities) requires verification. The metabolic processes of ingested garlic polysaccharides/oligosaccharides (as food ingredients/dietary supplements), their modes of action in healthy humans or populations with chronic conditions, and molecular/chain organization-bioactivity relationships remain unclear. Future research directions related to garlic polysaccharides/oligosaccharides are discussed.

Preparation, structural characterization and antioxidant activity of water-soluble polysaccharides and purified fractions from blackened jujube by an activity-oriented approach.

This study aimed to investigate the structural features and antioxidant activity in vitro of crude blackened jujube polysaccharides (BJPs) and five purified polysaccharides based on the activity-oriented approach. The crude BJPs exhibited dose-dependent radical scavenging activity and total reducing capacity, and provided excellent protective effects against H2O2-damaged HUVECs via up-regulating mitochondrial membrane potential and down-regulating intracellular reactive oxygen species. After fractionation by column chromatography, the five purified components differed in chemical composition, molecular weight, monosaccharide composition (type and relative proportion) and FTIR band (peak pattern or intensity, especially in the range of 1000.0-1200.0 cm-1), as well as protective effects against H2O2-induced HUVECs. As the most abundant and potent antioxidant component, the backbone of BJP-3 was mainly composed of →4)-α-l-GalpA (1→, →5)-α-l-Araf (1→ residues with two terminals of T-α-l-Araf (1→ and T-ß-d-Galp (1→. The above results compared the structural and bioactive properties of different blackened jujube polysaccharides and highlighted their potential as antioxidants for functional foods.

Effect of blend oil on the volatile aroma profile and storage quality of garlic paste.

The aim of this study was to evaluate the effect of edible oil on the volatile aroma profile and storage quality of garlic paste, and to explore the underlying mechanisms. The administration of blend oil at 40 °C in a garlic to oil ratio of 1.8 had a higher overall acceptance by affective sensory test. Compared with the original garlic paste, the sensory aroma profile of the oil-immersed garlic paste was characterized by suppressed pungency, garlic scent and garlic odor, and enhanced oil scent. SPME-GC-MS and HS-GC-IMS showed that the application of blend oil caused great changes in the level of some compounds, which could explain its role in the oil-immersed garlic paste. Furthermore, the blend oil also reduced the growth rate of the total number of colonies and browning intensity, and inhibited the loss of allicin. Therefore, the application of blend oil in garlic paste improved the sensory aroma and delayed the deterioration of the product quality.

AuNPs/NiFe-LDHs-assisted laser desorption/ionization mass spectrometry for efficient analysis of metronidazole and its metabolites in water samples.

Gold nanoparticles (AuNPs) have been widely used as laser desorption/ionization mass spectrometry (LDI-MS) nanomaterials for the analysis of low-molecular-weight samples. Nickel/iron-layered double hydroxides (NiFe-LDHs) nanosheets can support the anchoring of AuNPs and enhance the ability of desorption/ionization. Their hybrid nanocomposites are expected to produce synergistic effects to improve the performance of LDI-MS. In this work, a novel AuNPs/NiFe-LDHs nanomaterial was synthesized by self-assembly method and characterized based on TEM, SEM, XPS, UV-vis and FTIR-ATR. AuNPs/NiFe-LDHs assisted LDI-TOF MS exhibited higher peak intensity and lower background noise compared with conventional organic matrices. Furthermore, excellent salt and protein tolerance, good repeatability and quantification were observed when MNZ and its metabolites were detected in the range of 1-50 ng·µL-1 (R2 > 0.98), with LODs and LOQs of 0.5 ng·µL-1 and 1 ng·µL-1, respectively. This nanocomposite could also be used for the analysis of some other small molecules, such as antibiotics, sugars, amino acids and pesticides, demonstrating the potential to detect a variety of environmental chemicals. Taken together, the developed method combined the advantages of two nanomaterials and can provide rapid and accurate analysis of MNZ and its metabolites in water samples, as well as some other small molecules.

Pediococcus acidilactici Strains Improve Constipation Symptoms and Regulate Intestinal Flora in Mice.

Constipation is a prevalent gastrointestinal disorder that seriously reduces the quality of life. Clinical studies have shown that a great change or severe imbalance occurs in the intestinal microbiota of people with constipation. This study explored whether bacteriocin-producing and non-bacteriocin-producing Pediococcus acidilactici strains resulted in differences in the alleviation of constipation and changes in the fecal flora in BALB/c mice. The constipation-related indicators, gastrointestinal regulatory peptides and gut microbiota were identified to evaluate their alleviating effects and underlying mechanisms. The time to the first black-stool defecation and the gastrointestinal transit rate in constipated mice were found to be somewhat improved by four P. acidilactici strains (P > 0.05). Moreover, there were significant differences in the level of most gastrointestinal regulatory peptides in the serum, as well as in the composition and abundance of intestinal microbiota in different groups (P < 0.05). At the phylum level, the relative abundance of Firmicutes was significantly increased, but those of Bacteroidetes and Proteobacteria were significantly reduced after the administration of four P. acidilactici strains for 14 d (P < 0.05). The levels of Bacteroides and genera from Enterobacteriaceae were significantly decreased, whereas Bifidobacterium and Lactobacillus were upregulated when bacteriocin-producing P. acidilactici CCFM18 and CCFM28 strains were provided in the diet (P < 0.05). The results indicated that although constipation-related symptoms were alleviated to only a limited degree, the administration of four P. acidilactici strains effectively regulated the gut flora and provided a potential health benefit to the host, especially the bacteriocin-producing P. acidilactici strains.

Structural characterization and antioxidant activities of one neutral polysaccharide and three acid polysaccharides from the roots of Arctium lappa L.: A comparison.

In this work, we comparatively analyzed the structure and antioxidant activities of different polysaccharide fractions from Arctium lappa L. A total of four water-soluble polysaccharide fractions (ALP-1, ALP-2, ALP-3 and ALP-4) were obtained from the roots of Arctium lappa L. They differed in monosaccharide composition, molecular weight and linkage mode. ALP-1 and ALP-2 mainly consisted of fructose, with average molecular weights of 2.676 × 103 and 2.503 × 104 g/mol, respectively. ALP-3 and ALP-4 were mainly composed of fructose, arabinose and galactose, with average molecular weights of 9.709 × 104 and 6.790 × 104 g/mol, respectively. Furthermore, Fourier transform infrared spectrometry, methylation analysis and nuclear magnetic resonance spectroscopy suggested that the main polysaccharide ALP-1 had a linear chain of (1 → 2)-linked ß-D-Fructofuranosyl backbone (n ≈ 15) linked to a terminal (1 → 2)-linked α-d-Glucopyranosyl at the non-reducing end. All five polysaccharides displayed high antioxidant ability, especially ALP-4 in H2O2-induced HepG2 cell model and ALP-1 in metronidazole [MET]-induced zebrafish model. These findings provided comparative information on the structure and biological activity of different burdock polysaccharides and highlighted their potential as antioxidants in functional foods.

Structural characterization and antioxidant activities of one neutral polysaccharide and three acid polysaccharides from Ziziphus jujuba cv. Hamidazao: A comparison.

A neutral polysaccharide (HJP-1a) and three acid polysaccharides (HJP-2, HJP-3 and HJP-4) were obtained from Z. jujuba cv. Hamidazao. HJP-1a was mainly composed of arabinose and galactose in a ratio of 56.9:20.0, with an average molecular weight of 3.115 × 104 g/mol. HJP-2, HJP-3 and HJP-4 were homogeneous heteropolysaccharides mainly containing galacturonic acid, arabinose and galactose, with average molecular weights of 4.590 × 104, 6.986 × 104 and 1.951 × 105 g/mol, respectively. Structural characterization indicated that the backbone of HJP-3 appeared to be mainly composed of →4)-α-d-GalpA (1→ and →2,4)-α-l-Rhap (1→ residues with some branches consisting of →5)-α-l-Araf (1→ residues and terminals of T-α-l-Araf (1→ and T-ß-d-Galp residues. The four purified fractions displayed dose-dependent radical scavenging activity on ABTS+ radicals and reducing capacity, as well as excellent protective effect on H2O2-induced HepG2 cells and metronidazole-damaged zebrafish embryos, especially HJP-2 in vitro and HJP-1a in vivo. Therefore, the polysaccharides from Z. jujuba cv. Hamidazao could be used as a potential antioxidant in functional foods.

Effect of different combined mechanical and thermal treatments on the quality characteristics of garlic paste.

The aim of this study was to investigate the effects of the sequence of different thermal and mechanical treatments on the physicochemical parameters and microstructure of garlic paste, in order to improve the quality of the product. The total organosulfur compounds (OSCs) decreased steadily in blended-heated garlic, whereas OSCs decreased sharply after 2 min at 75 °C or 5 min at 85 and 95 °C in heated-blended garlic. After blanching for 5 min, allicin could maintain over 4.0 mg/g only at 75 °C; and OSCs of heated-blended garlic paste were found to drop by 29.56%, 90.63% and 94.79% at 75, 85 and 95 °C, respectively. In blended-heated garlic, the color values of L* (lightness) and a* (redness) decreased (P < 0.05), while the b* (yellowness) and C* (chroma) increased (P < 0.05), obtaining green discoloration garlic paste. The total color differences of blended-heated samples were greater than 12.08, which were 2-6 folds higher compared with heated-blended garlic. Total phenolic content and antioxidant activity decreased (P < 0.05) in all thermal treatments, thermal treatment of heated-blended garlic less than 5 min maintained over 30% of antiradical activity. The sequence of unit operations determined the pattern of garlic microstructure disruption, resulting in various enzymic and non-enzymic reactions. Our results indicated that use of heat treatment prior to blend processing is an effective and feasible method to inhibit garlic discoloration and retain high content of bioactive OSCs. It is recommended that garlic paste be prepared using heated-blended processing, with thermal processing limited to 75 °C for less than 5 min.

Effect of blanching and freezing on the physical properties, bioactive compounds, and microstructure of garlic (Allium sativum L.).

The aim of this work was to evaluate the impact of blanching on the physical properties of frozen garlic cloves and to explore the relationship between quality changes and microstructure. A short-term blanching treatment (100 °C  for 45 s, 90 °C  for 45 s, and 80 °C  for 60 s) before freezing did not affect the total organosulfur compound content. In a preliminary research, blanching conditions were determined to be 100 °C  for 45 to 80 s. Under these conditions, peroxidase was inactivated, but organosulfur compounds were retained. Mechanical and color tests showed a damaging effect of blanching and freezing on frozen garlic blanched for 60 and 80 s at 100 °C . Compared to frozen fresh garlic, frozen garlic treated by blanching for 45 s at 100 °C  retained 2871.49 ± 200.24 µg/g of allicin, although 81.83% of peroxidase was inactivated; browning and hardness improved by 49.97 and 48.01%, respectively. According to scanning electron microscopy, significant damage to the microstructure was observed in both frozen fresh garlic and frozen garlic after 60 s and 80 s of blanching at 100 °C . Moreover, 1 H low-field nuclear magnetic resonance (LF-NMR) indicated that blanching for 60 s and 80 s induced an increase in free water in garlic tissues, resulting in further damage after freezing. As peroxidase was efficiently inactivated, the microstructure and organosulfur compounds were better preserved, and blanching treatment at 100 °C  for 45 s before freezing is a potential method for obtaining frozen garlic with high sensory and nutritional qualities. PRACTICAL APPLICATION: Freezing helps to overcome challenges associated with growing seasons and the deterioration of garlic during storage. After frozen garlic is thawed, it is prone to some undesirable changes, such as enzymatic browning and softening. Minimal blanching (45 s at 100 °C ) pretreatment can help to maintain the bioactive compounds of garlic and prevent texture and color deterioration caused by freezing directly.

Formation, nutritional value, and enhancement of characteristic components in black garlic: A review for maximizing the goodness to humans.

Black garlic (BG) is essentially a processed food and obtained through the transformation of fresh garlic (FG) (Allium sativum L.) via a range of chemical reactions (including the Maillard reaction) and microbial fermentation. This review provides the up-to-date knowledge of the dynamic and complicated changes in major components during the conversion of FG to BG, including moisture, lipids, carbohydrates (such as sugars), proteins, organic acids, organic sulfur compounds, alkaloids, polyphenols, melanoidins, 5-hydroxymethylfurfural, vitamins, minerals, enzymes, and garlic endophytes. The obtained evidence confirms that BG has several advantages over FG in certain product attributes and biological properties (especially antioxidant activity), and the factors affecting the quality of BG include the type and characteristics of FG and processing technologies and methods (especially pretreatments, and processing temperature and humidity). The interactions among garlic components, and between garlic nutrients and microbes, as well as the interplay between pretreatment and main manufacturing process, all determine the sensory and nutritional qualities of BG. Before BG is marketed as a novel snack or functional food, more research is required to fill the knowledge gaps related to quantitative monitoring of the changes in metabolites (especially those taste-active and/or biological-active substances) during BG manufacturing to maximize BG's antioxidant, anticancer, antiobesity, anti-inflammatory, immunostimulatory, anti-allergic, hepatoprotective, cardioprotective and oxidative stress-/hangover syndrome-reducing functions, and beneficial effects on memory/nervous systems. Assessments of the quality, efficacy, and safety of BG should be performed considering the impacts of BG production conditions, postproduction handling, and intake methods.