Effect of pretreatment on physicochemical, microbiological, and aflatoxin quality of solar sliced dried ginger (Zingiber officinale Roscoe) rhizome

Fluorescence lifetime imaging microscopy as a tool to characterize spice powder variations for quality and authenticity purposes: A ginger case study

Spices are usually ground for applications and the resulting particle size of the powders is an important product attribute in view of the release of flavour. However, inhomogeneity of the original material may lead to variations in the physicochemical characteristics of the particles. This variation and its linkage to particle size may be examined by particular imaging techniques. This study aimed to explore the potential of Fluorescence Lifetime Imaging Microscopy (FLIM) to characterize spice powders according to particle size variations and correlation with their pigment contents to reveal the chemical information contained within the FLIM data. Ginger powder was used as a representative powder model. The FLIM profiles of the individual samples and populations revealed that FLIM coupled with the phasor approach has the capacity to characterize spice powder according to particle size. Meanwhile, Principal Component Analysis of pre-processed FLIM data revealed clustering of particle size groups. Further correlation analysis between the pigment compound contents and FLIM data of the ginger powders indicated that FLIM reflected chemical information of ginger powder and was able to visualize endogenous fluorophores. The current study revealed the potential of FLIM to characterize ginger powder particles. This approach may be extrapolated to other spice powder products. The new knowledge is a step further in paving the way for the application of innovative techniques, already prevalent in other domains, to food quality and authentication.

Interpreting the variation in particle size of ground spice by high-resolution visual and spectral imaging: A ginger case study

High-resolution (HR) visual imaging and spectral imaging are common computer vision-based techniques used for food quality analysis and/or authentication based on the interaction of light and material surface and/or composition. The particle size of ground spices is an important morphological feature that affects the physico-chemical properties of food products containing such particles. This study aimed to interpret the impact of particle size of ground spice on its HR visual profile and spectral imaging profile using ginger powder as a representative spice powder model. The results revealed an increase in the light reflection with the decrease of particle size of ginger powder, which was manifested by the lighter colour (higher percentage of the colour code with lighter yellow colour) of the HR visual image and stronger reflection with spectral imaging. The study also revealed that, in spectral imaging, the influence of the particle size of ginger powder increased with rising wavelengths. Finally, the results indicated a relationship between spectral wavelengths, ginger particle size, and other natural variables of the products which might be generated from cultivation to processing. Ultimately, the impact of natural variables arising during the food production process on the physico-chemical properties of the product should be fully considered or even additionally evaluated prior to the application of specific food quality and/or authentication analytical techniques.

Effects of sulfite treatment on the quality of black fungus

In the present study, the color, total sugar, contents of soluble protein, total polyphenols, total flavonoids, and soluble vitamins, and other indicators of black fungus treated with sodium metabisulfite under different conditions were measured to evaluate the sensory and nutritional changes in black fungus after sulfite treatment. The results showed that use of sodium metabisulfite increased the lightness of black fungus, significantly increased the contents of total polyphenols and reducing sugars in the fungus (p < 0.05), increased the content of soluble protein, and decreased the content of total flavonoids. In addition, sodium metabisulfite destroyed vitamin C and B₁ in black fungus. When the concentration of sodium metabisulfite was 0.5% and the soaking time 20 or 30 min, the color of black fungus improved markedly, and nutrients were not negatively affected. Therefore, the use of sodium metabisulfite improved the quality of fungus to a certain extent.

Assessment of some quality parameters and chemometric-assisted FTIR spectral analysis of commercial powdered ginger products on the Ghanaian market

Background

Zingiber officinale Roscoe (ginger) rhizome is a global spice with marked pharmacological activities and industrial applications. The demand for the powdered spice soared in the wake of the COVID-19 global pandemic. The present study sought to assess powdered ginger products on the Ghanaian market for some quality parameters and compare their chemical composition via chemometric analysis of their FT-IR data.

Methods

A survey was conducted in three major markets in Ghana to determine the commercially available powdered ginger products. These products were purchased and assessed for microbial load, heavy metals contents and ash values using official methods. Also, principal component and hierarchical cluster analysis, as multivariate algorithms, were applied to their FT-IR spectral fingerprints, using Z. officinale, Z. zerumbet and some dried ginger rhizomes from Nigeria as reference samples.

Results

Seven products were found in the survey: three local and four foreign. The local products failed to meet regulatory label requirements. The microbial load, heavy metals and ash values of all commercial samples were generally within specifications except for the aerobic bacterial counts of some local samples. Pharmacopoeial identity test and the chemometric analysis revealed all the products to contain Z. officinale. The reference ginger sample from Nigeria also demonstrated some level of similarity with Z. officinale. The variations in physical attributes and slight difference in chemical composition of the different products was presumed to be due to chemical changes arising from different processing methods and possible adulteration with other flours.

Conclusion

The sampled ginger products on the market originate from Z. officinale and have quality attributes that make them suitable for food and medicinal applications. The observed deviations, however, suggest an urgent need for standardized processing methods to ensure consistency in quality indices, as well as regular quality checks by regulatory bodies.

Effects of Pretreatment and Drying on the Volatile Compounds of Sliced Solar-Dried Ginger (Zingiber officinale Roscoe) Rhizome

Ginger (Zingiber officinale Roscoe) rhizomes are mostly used as spice and medicine due to their high aroma intensity and medicinal bioactive compounds. However, the volatile compounds of ginger, partly responsible for its aroma and medicinal properties, can be affected by the pretreatment, drying method, and extraction processes employed. The objective of this study was to assess the effects of pretreatment and drying on the volatile compounds of yellow ginger variety at nine months of maturation. The effect of potassium metabisulfite (KMBS) and blanching pretreatment and drying on the volatile compounds of ginger using head space solid-phase microextraction with GCMS/MS identification (HS-SPME/GCMS/MS) was investigated. KMBS of concentrations 0.0 (control), 0.1, 0.15, 0.2, and 1.0% and blanching at 50°C and 100°C were used for pretreatment and dried in a tent-like concrete solar (CSD) dryer and open-sun drying (OSD). The different concentrations of KMBS-treated fresh ginger rhizomes did not result in any particular pattern for volatile compound composition identification. However, the top five compounds were mostly sesquiterpenes. The 0.15% KMBS-treated CSD emerged as the best pretreatment for retaining α-zingiberene, β-cubebene, α-farnesene, and geranial. The presence of β-cedrene, β-carene, and dihydro-α-curcumene makes this study unique. The 0.15% KMBS pretreatment and CSD drying can be adopted as an affordable alternative to preserve ginger.

Vacuum pressure combined with osmosonication as an innovative pre-drying technique for Ghanaian ginger: Evidence from the metabolome and quality characteristics of the dried product

We assessed the impact of selected pretreatment techniques, thus, vacuum-assisted osmotic dehydration (VOD), vacuum-assisted sonication (VSON) and vacuum-assisted osmosonication (VOS) on the metabolomes and quality characteristics of infrared-dried ginger slices. We found marked metabolome differences between the pretreated ginger samples, evidenced by differential amounts of 6-gingerol and 6-shogaol, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities. We also found distinct differences in the drying kinetics and sensory characteristics of the pretreated samples. Generally, VOS pretreatment gave the best outcomes. The VOS-pretreated samples contained the highest contents of the marker compounds, TPC, TFC and gave the best antioxidant activity. The VOS-pretreated samples also recorded the shortest drying time and exhibited the best sensory attributes. Overall, the general order observed was, VOS > VSON > VOD > control for all quality parameters examined. VOS pretreatment of ginger before drying therefore holds a great potential for large-scale industrial application.