Effect of Drying Methods and Processing Conditions on the Quality of Curcuma longa Powder

A comprehensive review on ultraviolet disinfection of spices and culinary seeds and its effect on quality

Spices and culinary seeds, valued for their flavor and aroma, pose unique challenges for disinfection, as heat treatments are often unsuitable. Their raw consumption increases the risk of contamination, particularly with Salmonella spp. Thermal treatments are widely used for food disinfection due to their effectiveness in inactivating bacteria. However, these methods often degrade the nutritional and sensory qualities of food. Ultraviolet (UV) light, however, is a promising nonthermal technique that balances microbial inactivation and food quality preservation. This review employed a systematic approach to evaluate the effects of UV treatments, both alone and in combination with other techniques, on the microbiological safety and chemical composition of spices and culinary seeds. UV treatments have been shown to effectively inactivate bacteria, molds, and mycotoxins without triggering the same chemical reactions that reduce the quality of plant-based foods. Some studies have even suggested improvements in nutritional parameters following UV exposure, such as the increase of antioxidant activity or total phenolic content. However, inconsistencies in study quality limit the strength of current conclusions, and further research is needed. Critical areas for future investigation include scaling UV reactors, combining treatments, exploring UV-LED technology, conducting sensory analyses, and studying the inactivation of bacterial spores and mycotoxins.

Impact of Drying Methods on Phenolic Composition and Bioactivity of Celery, Parsley, and Turmeric-Chemometric Approach

Drying is one of the most commonly used methods for food preservation, and in spice processing, it has a significant impact on quality. In this paper, the influences of drying at room temperature, 60 °C, and 90 °C and freeze-drying on celery and parsley roots and turmeric rhizomes were examined. The highest content of total phenolics was found in celery dried at 60 °C (C60), parsley at room temperature (PRT), and freeze-dried turmeric (TFD) (1.44, 1.58, and 44.92 mg GAE/gdm, respectively). Celery dried at room temperature (CRT), PRT, and TFD showed the highest antioxidant activity regarding the DPPH and ABTS radicals and FRAP. The analysis of color parameters revealed that celery dried at 90 °C (C90); PFD and TFD showed the most similar values to control samples. The drying process was optimized using a combination of standard score (SS) and artificial neural network (ANN) methods. The ANN model effectively evaluated the significance of drying parameters, demonstrating high predictive accuracy for total phenolics, total flavonoids, total flavonols, total flavan-3-ols, IC50ABTS, and FRAP. TFD showed the strongest α-glucosidase inhibitory potential. Also, TFD extract showed good antibacterial activity against Staphylococcus aureus but not against Escherichia coli. C90 and PFD extracts did not show antibacterial activity against the tested microorganisms.

Characterization of Lactic Acid Bacteria Isolated From Rotting Oranges and Use of Agropastoral Processing By-products as Carbon and Nitrogen Sources Alternative for Lactic Acid Production

This study investigated the ability of lactic acid bacteria (LAB) isolated from oranges to use fish by-products (FB) and chicken by-products (CB) as nitrogen sources alternative to yeast extract for lactic acid (LA) production in a papaya by-product medium as a carbon source. Once the fermentation agents had been isolated, they were subjected to biochemical and molecular characterization. Inexpensive nitrogen sources, precisely CB and FB, were prepared, freeze-dried, and yield evaluated. Also, before to the fermentation experiments, the Total Kjehdahl Nitrogen (TKN) of these by-products and that of the yeast extract were determined. Then, three production media differing in terms of nitrogen source were formulated from these nitrogen sources. From the 22 LAB isolated from orange, two isolates of interest (NGO25 and NGO23) were obtained; all belonging to the Lactiplantibacillus plantarum species based on 16S rRNA gene sequencing. Furthermore, the production yield powder obtained after lyophilization of 1 L of CB and FB surpernatant were, respectively, 16.6 g and 12.933 g. The TKN of different nitrogen sources powder were 71.4 ± 0.000% DM (FB), 86.145 ± 0.001% DM (CB), and 87.5 ± 0.99% DM (yeast extract). The best kinetic parameters of LA production (LA (g/L): 31.945 ± 0.078; volumetric productivity (g/L.h): 1.331 ± 0.003; LA yield (mg/g) 63.89 ± 0.156; biomass (g/L) 7.925 ± 0.035; cell growth rate (g/L.h): 0.330 ± 0.001) were recorded by Lactiplantibacillus plantarum NGO25 after 24 h of fermentation. The latter data were obtained in the production medium containing CB as nitrogen sources. In addition, this production medium cost only $0.152 to formulate, compared to yeast extract which required $1.692 to formulate. Thus, freeze-dried CB can be used as an alternative to yeast extract in large-scale production of LA.

Curcuminoid Contents in Rhizomes of Some Zingiberaceous Plants Sold via Online Platforms: Influence of Species and Cultivation Location

Zingiberaceous plants are versatile and find application in various fields, including food, medicine, and cosmetics. Recently, turmeric and other Zingiberaceous plants have become readily available through online platforms. However, the quality, specifically the curcuminoid content, has not been adequately assessed. In light of this issue, this study is aimed at analyzing the curcuminoid contents, including bisdemethoxycurcumin, demethoxycurcumin, and curcumin, using high-performance liquid chromatography. The analysis targets the rhizomes of Zingiber montanum (ZM), Curcuma aromatica (CA), Curcuma wanenlueanga (CW), Curcuma zedoaria (CZ), and sixteen Curcuma longa (CL) samples sold on online platforms. The influence of species and cultivation locations was evaluated, compared, and clustered. The results indicated that CL exhibited the highest curcuminoid contents, followed by CA, CZ, ZM, and CW, respectively. Curcumin was not detected in CW, while bisdemethoxycurcumin and demethoxycurcumin were absent in ZM. Cluster analysis revealed that CW was closely related to ZM, and CA was closely related to CZ, while CL was not closely related to either cluster. Among the sixteen CL samples, the most commonly found curcuminoids were curcumin, followed by bisdemethoxycurcumin and demethoxycurcumin, respectively. Three samples contained curcuminoid contents of less than 5%, failing to meet the standard level specified in the Thai Herbal Pharmacopoeia. Furthermore, ten samples had total curcuminoid contents higher than 10%, with three samples exceeding 15%. The top three samples with the highest total curcuminoid contents from different locations were as follows: Tha Yang District, Phetchaburi Province (17.02%); Phop Phra District, Tak Province (16.97%); and Pak Tho District, Ratchaburi Province (15.45%). Cluster analysis revealed that CL samples could be grouped into two major categories: low curcuminoid and high curcuminoid groups. This study offers valuable insights for consumers seeking high-quality rhizomes of Zingiberaceous plants with high curcuminoids, through online platforms. By focusing on the curcuminoid content, consumers can make informed decisions when purchasing Zingiberaceous plants online. This information not only aids in selecting superior quality rhizomes but also enhances the overall consumer experience by ensuring the potency and efficacy of the purchased products.

Comparative GC-MS Analysis of Fresh and Dried Curcuma Essential Oils with Insights into Their Antioxidant and Enzyme Inhibitory Activities

Species belonging to the Zingiberaceae family are of high nutritional, industrial, and medicinal values. In this study, we investigated the effect of processing steps (fresh vs. dried milled rhizomes) and extraction methodologies (hydrodistillation vs. hexane extraction) of curcuma essential oil on its chemical content (using GC-MS analysis), its antioxidant behavior (using in vitro assays such as DPPH, ABTS, CUPRAC, FRAP, phosphomolybdenum, and metal chelation), and its enzyme inhibitory activities (on tyrosinase, acetylcholinesterase, butylcholinesterase, α-amylase, and α-glucosidase) supported by multivariate analysis, in silico studies, and molecular dynamics. The GC-MS investigations revealed a high degree of similarity in the chemical profile of fresh hydrodistilled and hexane-extracted essential oils with tumerone and curlone being the major metabolites. The extraction techniques affected the concentrations of other minor constituents such as terpinolene, caryophylla-4(12), 8(13)-dien-5α-ol, and neo-intermedeol, which were almost exclusively detected in the hydrodistilled fresh essential oil; however, zingiberene and β-sesquiphellandrene were predominant in the hexane-extracted fresh essential oil. In the dried curcuma rhizomes, tumerone and curlone contents were significantly reduced, with the former being detected only in the hydrodistilled essential oil while the latter was doubly concentrated in the hexane-derived oil. Constituents such as D-limonene and caryophyllene oxide represented ca. 29% of the dried hydrodistilled essential oil, while ar-turmerone was detected only in the dried hydrodistilled and hexane-extracted essential oils, representing ca. 16% and 26% of the essential oil composition, respectively. These variations in the essential oil chemical content have subsequently affected its antioxidant properties and enzyme inhibitory activities. In silico investigations showed that hydrophobic interactions and hydrogen bonding were the characteristic binding modes of the bioactive metabolites to their respective targets. Molecular dynamics revealed the stability of the ligand-target complex over time. From the current study we conclude that fresh hexane-extracted essential oil showed the best radical scavenging properties, and fresh rhizomes in general display better enzyme inhibitory activity regardless of the extraction technique.