Comparative study of nutritional properties and antioxidant activity of raw and fermented (black) garlic

Nutritional and Bioactive Compounds, Antioxidant Properties and Antibacterial Activity of Chinese Chive (Allium odorum L.)

The present study was conducted to generate the comprehensive data on the nutritional composition, minerals, heavy metal, bioactive compounds, antioxidant and antibacterial properties of Chinese chive (Allium odorum L.) grown at two different locations including Manipur and Punjab. The crop grown in Manipur exhibited higher values of nutritional and phytochemical compound values than those grown in Punjab. It exhibited significantly higher amounts of crude protein, crude fiber, potassium, calcium and iron content in the Manipur environment. The allicin content in leaves of Chinese chive on a dry weight (dw) varied from 1.31 to 1.4% and there was non-significant difference in allicin content at both locations. Besides, the heavy metal content of Chinese chive was much below the permissible limits of the World Health Organization. The IC50 value of Chinese chive was 78.908-95.140 µg/ml which imparts strong antioxidant activity and higher DPPH (2,2-diphenyl-1-picrylhydrazyl)radical scavenging activity higher in fresh leaves than dried leaves. Total phenol and total flavonoid were found to be significantly high. In addition, high antibacterial activities were observed against toxin producing pathogenic bacterial strains of Staphylococcus aureus and Enterococcus faecalis. The nutritional and bioactive compounds, antioxidant properties and antibacterial activity of Chinese chive make it ideal for its use as a functional food and/or supplement.

Comments on "health-promoting properties of bioactive proteins and peptides of garlic (Allium sativum)", food chemistry 435 (2024) 137632-137,643, DOI: 10.1016/j.foodchem.2023.137632

The article "Health-promoting properties of bioactive proteins and peptides of garlic (Allium sativum)" by Ezeorba et al. (Food Chemistry 435 (2024) 137632-137,643, DOI: https://doi.org/10.1016/j.foodchem.2023.137632), offers a comprehensive review of the literature on the bioactive proteins and peptides found in garlic. This study serves as a valuable resource for professionals in the fields of research, nutrition, and healthcare who are interested in the medicinal and nutritional aspects of garlic. This Letter to the Editor aims to address some inaccuracies and omissions found in the above-mentioned article. It corrects the reported lack of biological activity data for certain peptides, clarifies the immunomodulatory effects attributed to garlic's components, and adjusts the reported protein content range for garlic varieties. These refinements aim to enhance the accuracy and utility of the information presented in this article for future research.

Comparative content analysis and biological activity studies of fatty and essential oils from some garlic products sold in Turkish community pharmacies, natural, and fermented garlic

Garlic (Alliaceae), an annual herb, is renowned not only for its distinctive flavor but also for its extensive therapeutic applications in managing various ailments and health conditions. In this study, garlic products identified as the best-selling items in Turkish pharmacies for various purposes were compared with garlic grown under standard conditions in terms of chemical composition and antidiabetic, anticholinesterase, antimicrobial, and antioxidant properties. Three of garlic samples were prepared by researchers. According to survey results, the most commonly sold garlic-related products in pharmacies are black garlic extract tablets (4), capsules (5), garlic oil (6), garlic oil pearls (7), and fermented garlic (8). Diallyl disulfide (DADS) was identified as a predominant compound in sampled oils, ranging from 4.9% to 48.6%. Another noteworthy finding is the identification of allyl methyl disulfide and allyl methyl trisulfide as major components in sampled oils, with concentrations spanning from 2.9% to 9.8% and 0.4% to 17.5%, respectively. In both 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS·+) and 2,2-diphenyl-1-picrylhydrazyl (DPPH•) tests, Sample 1 (fermented) exhibited the highest antioxidant activity. Sample 3 (cultivated) was richer in total phenol-total tannin content. Sample 6 exhibited the highest α-glucosidase inhibition among antidiabetic activities, reaching 28.93%. Sample 5 capsules demonstrated the highest α-amylase inhibition at 51.50%. Sample 7 exhibited the most notable inhibition against both acetylcholinesterase (22.92%) and butyrylcholinesterase (13.37%). Samples 3, 6, and 8 were found to be more effective against Candida tropicalis with minimum inhibitory concentration (MIC) = 625 μg/mL. A comprehensive study on garlic products, including popular items from Turkish pharmacies and those grown under standard conditions, revealed diverse chemical compositions and multifaceted health properties.

The Impact of Fermentation on the Antioxidant Activity of Food Products

From ancient times to the present day, fermentation has been utilized not only for food preservation but also for enhancing the nutritional and functional properties of foods. This process is influenced by numerous factors, including the type of microorganisms used, substrate composition, pH, time, and temperature, all of which can significantly alter the characteristics of the final product. Depending on the parameters, fermentation enhances the bioactive content of the products and imparts the necessary properties, such as antioxidant characteristics, for the products to be considered functional. The enhancement of these properties, particularly antioxidant activity, enriches foods with bioactive compounds and functional attributes, contributing to improved health benefits. Through a review of recent research, this study elucidates how different fermentation processes can enhance the bioavailability and efficacy of antioxidants, thereby improving the nutritional and functional qualities of foods. This study investigated the multifaceted effects of fermentation on antioxidant properties by exploring various types and conditions of fermentation. It highlights specific examples from dairy products and other food categories as well as the valorization of food waste and byproducts. The findings underscore the potential of fermentation as a sustainable method to produce health-promoting foods with elevated antioxidant activities, offering new perspectives for food science and technology.

Comparative study of antioxidant activities of Allium sativum (a novel variety, HG17) and Allium ampeloprasum (SMG): Revealing the higher potential of HG17 and analyzing its phytochemicals

Garlic, belonging to the genus Allium, is renowned for its rich antioxidant potential. Snow Mountain garlic (SMG) (Allium ampeloprasum) has been traditionally used for medicinal purposes because of its higher antioxidant potential. Considering its potential in medical therapies, we compared the antioxidant activity of SMG with a novel variety of Allium sativum, Hisar garlic 17 (HG17). Comparative antioxidant activity data (2,2-diphenyl-1-picrylhydrazyl and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) revealed the higher antioxidant activity of HG17 than SMG, which prompted us to conduct a comprehensive phytochemical investigation to elucidate the factors contributing to antioxidant potential of HG17. To get a detailed antioxidant and phytoconstituents profiling, we differentially extracted HG17 by processing it in different forms (fresh, dry, heated, and aged) with two solvents (50% methanol and n-butanol). Our data (antioxidant activities, total phenolics, and flavonoids) showed that dry garlic methanolic extract (DgM) had maximum potential than other HG17 forms/solvents, which concludes that different extraction techniques had direct impact on the phenolics/flavonoids and antioxidant potential of the extracts. Further, phytochemical analysis of HG17 extracts by high resolution liquid chromatograph mass spectrometer quadrupole time of flight validated the maximum potential of DgM. LCMS revealed the presence of garcimangosone C, osmanthuside A, and protoaphin aglucone polyphenols exclusively in DgM compared to other HG17 extracts, which possibly contributing in its high antioxidant potential. The overall differential extraction and LCMS data of HG17 strongly depict that it may be used as an alternative of SMG under diverse medical applications. HG17 higher antioxidant potential and rich array of unique phytochemicals make it valuable for food and pharmaceutical industries to integrate into functional foods/therapeutics. PRACTICAL APPLICATION: Garlic unique phytochemical composition and its remarkable ability to scavenge different radicals make it valuable therapeutic asset to mitigate diseases associated with oxidative stress. SMG is well known for its anti-arthritic and anti-inflammatory properties. HG17 showed higher antioxidant potential than SMG and can be used as an alternative of SMG for anti-arthritic properties.

Changes in Garlic Quality during Fermentation under Different Conditions

One of the garlic processing methods is fermentation, which produces black garlic with completely different chemical, physical, sensory, culinary, and health-enhancing properties. Our study aimed to compare the influence of various processing conditions on the quality indicators of black garlic (BG). Samples of white garlic (WG) were placed in laboratory climatic chambers. BG1 samples were packed in plastic bags and vacuumed, BG2 and BG3 samples were packed in textile mesh bags. BG1 samples were fermented in 70% humidity at 50 °C for 28 days, BG2 samples in 85% humidity at 60 °C for 99 days, and BG3 samples in 80% humidity at 80 °C for 14 days. The dependence of changes in chemical composition, color, and texture of garlic on fermentation conditions was analyzed. Proximate composition analyses and antioxidant activity of WG and BG were performed using standard methods. It was established that regardless of the fermentation conditions, BG's chemical composition became richer than WG's. They significantly increased vitamin C content (1.5-5.8 fold), titratable acidity (14.7-21.0 fold), protein (1.4-3.2 fold), fiber (4.6-7.0 fold), and ash (1.2-3.9 fold) content, amount of total phenolic compounds (6.6-9.6 fold) and antioxidant activity (5.3-9.9 fold). Fermented garlic turned dark in color and soft and sticky in texture. The higher fermentation temperature (80 °C) but the shorter time (14 days) had the greatest positive effect on the quality of black garlic.

Determination of Post-Fermentation Waste from Fermented Vegetables as Potential Substitutes for Preservatives in o/w Emulsion

Post-fermentation wastes are rich sources of various biologically active compounds with antimicrobial activity, whose potential is not being fully exploited. One of the possible applications of post-fermentation waste may be its use as a natural preservative that effectively combats pathogens found in formulations. The study aims included the following: (1) compare the antimicrobial and antioxidant activity of fermented vegetable extracts (FVEs), (2) examine the inhibition of cosmetic-borne pathogens by FVEs, and (3) estimate the preservative effectiveness of FVEs in o/w emulsions. It was found that fermented white cabbage, cucumber, celery, and the mixture of fermented white cabbage, cucumber, and celery (1:1:1) showed antibacterial and antifungal activity against all the tested reference microbial strains. The addition of fermented cucumber, celery, and the mixture of fermented white cabbage, cucumber, and celery (1:1:1) to the o/w emulsion fulfilled criterion A of the preservative effectiveness test for S. aureus, E. coli, and A. brasiliensis, but did not fulfill the criterion for P. aeruginosa and C. albicans. The tested FVEs have comparable activity to inhibit pathogens in o/w emulsion as sodium benzoate. The results of our study prove that FVEs can be valuable raw materials supporting the preservative system, which, in turn, can significantly reduce the concentration of preservatives used in o/w emulsion.

Psychochemical changes and functional properties of organosulfur and polysaccharide compounds of black garlic (Allium sativum L.)

Background

Black garlic is one of the functional food products made from garlic which is processed through aging to improve sensory value and nutritional quality. Aging conditions has a major impact on the psychochemical and functional properties changes of black garlic which is closely related to organosulfur compounds and polysaccharides as the largest component in garlic.

Scope and approach

The method used in this research is a systematic review with the aim of research to determine the relationship between reactions during aging and changes in organosulfur, polysaccharides and non-enzymatic browning product compounds as well as the function of black garlic by focusing on certain aspects of aging including temperature, humidity, time, microorganism activity, and pre-treatment application.

Key findings and conclusions

Maillard reaction and polysaccharide degradation are still be the dominant reactions and play an important role in black garlic production. High hydrostatic pressure pretreatment could maintains the quality of black garlic so that the black garlic has the same taste characteristics as black garlic in general. Antioxidant properties in black garlic shown increase during thermal treatment. In addition, it is known that the activity of microorganisms plays a role and being potential to increase the quality value of black garlic as well as the antimicrobial activity.

Health-promoting properties of bioactive proteins and peptides of garlic (Allium sativum)

Garlic is a popular food spice with diverse and well-established medicinal properties. Many research interests have been directed toward the biological activities of the phytochemical constituents of garlic. However, prospects of its bioactive proteins and peptides have been understudied to date. With the advances in food proteomics/peptide research, a review of studies on garlic bioactive proteins and peptides, especially on their nature, extraction, and biological activities, is timely. Garlic has been reported to express several proteins, endogenous and protein-derived peptides with interesting bioactivities, including antioxidant, anti-inflammatory, antibacterial, antifungal, anti-proliferative, antiviral, anti-hypertensive and immunomodulatory activities, suggesting their therapeutic and pharmacological potentials. Compared to legumes, the low protein contents of garlic bulbs and their low stability are possible limitations that would hinder future applications. We suggest adopting heterologous expression systems for peptide overproduction and stability enhancement. Therefore, we recommend increased scientific interest in the bioactive peptides of garlic and other spice plants.

Comparison of Efficacy of Fermented Garlic and Orlistat (Lipase Inhibitor) in Obesity Management Using an Experimental Rodent Model

BACKGROUND

Black garlic, also known as fermented garlic, is a useful food that may have therapeutic benefits. The aim of this study was to analyze the impact of fermented garlic and orlistat therapy on obese rats.

METHODS

A total of 40 male albino rats (245-250 g) were fed either an HFD (n = 32) or a normal diet (n = 8) for 6 weeks; therefore we randomly assigned the rats into: group I (normal diet), group II (HFD), groups III and IV (HFD with fermented garlic), and group V (orlistat for) 6 weeks. Two different dosages of fermented garlic (481.2 mg/kg and 963.3 mg/kg) were administered. Afterward, blood was collected, body weight was measured, and tissue was collected for further analysis.

RESULTS

Both the orlistat and black garlic groups showed a significant reduction in BMI, lipid profiles, and insulin levels compared with the baseline. The orlistat group showed significant elevation (p < 0.005) in body weight, organ weight, lipids, and liver parameters, with histopathological findings. The administration of black garlic improved the inflammatory markers with all other parameters.

CONCLUSION

The fermented garlic and orlistat reinstated all of the investigated parameters significantly (p < 0.05), especially body weight and lipid profiles, and induced histopathological changes compared to the drug orlistat. Additionally, it showed anti-obesity-related therapeutic impacts compared with the orlistat drug. Black garlic provides a reliable and effective treatment for obesity compared to orlistat.

Lacto-fermented garlic sauce improved the quality and extended the shelf life of lamb meat under the chilled condition

This study evaluated the potential of fermented garlic as a marinated lamb sauce ingredient to improve the quality and shelf life of chilled lamb. Garlic was subjected to Lacto-fermentation for 72 h at 37 °C using Lacticaseibacillus casei. The ¹H NMR metabolomics profile showed the presence of eight amino acids and five organic acids in fermented garlic, indicating the attribution to the antioxidant and antimicrobial activities. The FRAP and DPPH assays of fermented garlic revealed antioxidant activities of 0.45 ± 0.09 mmol/100 g DW and 93.85 ± 0.02 %, respectively. Meanwhile, fermented garlic inhibited the growth of Escherichia coli (95 %), Staphylococcus aureus (99 %) and Salmonella Typhimurium (98 %). When fermented garlic was added to the marinade sauce, it successfully reduced the microbial load of lamb meat by 0.5 log CFU/g after 3 days of storage. There were no significant differences in color between the control and marinated lamb after 3 days of marinating in a sauce formulated with fermented garlic. Furthermore, marinated lamb significantly improved water-holding capacity, texture, juiciness, and overall acceptance. These findings indicated a potential addition of fermented garlic in marinade lamb sauce recipes to improve the quality and safety of meat products.

The Physicochemical Properties, Volatile Compounds and Taste Profile of Black Garlic (Allium sativum L.) Cloves, Paste and Powder

Black garlic is produced as a result of the so-called “fermentation processes” of whole heads or cloves kept under controlled conditions of temperature and humidity for several weeks. During this long-term heat treatment, garlic undergoes enzymatic and non-enzymatic browning reactions, which greatly change its taste, aroma, physicochemical, organoleptic and bioactive properties. Black garlic is most often produced in the form of cloves, and recently also in the form of paste and powder. This work focused on the comparison of functional properties of black garlic, such as volatile compounds, taste profile, total polyphenols content, antioxidant activity, color (CIE L*, a*, b*), water activity (aw), pH, soluble solids content (°Brix) and moisture content, depending on the form of its occurrence: cloves, spreading paste and powder. After long-term heat treatment, garlic was characterized by a higher content of dry matter and water-soluble solids, respectively at about 22% and 24% for spreading paste and 166% and 44% for powder. The conducted research showed significant differences in the bioactive properties of the tested garlic samples, with the lowest content of polyphenols and antioxidant properties in fresh, unprocessed garlic (6.05 ± 0.07 mg GAE/1 g d.m. and 232.95 ± 4.06 µM TEAC/1 g d.m., respectively), while in garlic subjected to long-term heat treatment, the total polyphenols content and antioxidant potential were two times higher than in the unprocessed garlic. The polyphenol content and antioxidant properties were the highest in the spread garlic (respectively, 15.16 ± 0.08 mg GAE/1 g d.m. and 638.46 ± 3.37 µM TEAC/1 g d.m.) and the lowest in the powdered samples (respectively, 11.02 ± 0.51 mg GAE/1 g d.m. and 541.71 ± 5.22 µM TEAC/1 g d.m.). Obtained black garlic samples gain completely different sensory characteristics determined using instrumental methods. In black garlic and its preparations, the intensity of unpleasant taste and aroma is reduced as a result of the appearance of metabolites during the long-term heat treatment, which in turn determined the specific, delicate sweet–sour taste and pleasant aroma, completely unrelated to the aroma of the unprocessed product. Taking into account the obtained results, it can be stated that black garlic, in the form of cloves, paste and powder, exhibits completely different properties than white garlic.