Induction of γ irradiation for decontamination and to increase the storage stability of black teas

Asparagus (Asparagus racemosus L.) roots: nutritional profile, medicinal profile, preservation, and value addition

Asparagus (Asparagus racemosus L.) is one of the most significant traditional medicinal plants, containing phytochemicals that are non-nutritive but beneficial to health. It contains bioactive metabolites such as fructo-oligosaccharides, polysaccharides, asparosides, shatavarins, sapogenins, racemosols, isoflavones, glycosides, mucilage, and fatty acids, while saponin is one of the main active constituents of asparagus roots. Asparagus helps in fertility promotion, stress management, and hormone modulation. It also treats stomach ulcers, kidney disorders, and Alzheimer's disease. Substitution of asparagus powder or extract for value addition of food products (such as beverages, bakery, and milk) enhances the nutritional and functional properties. Currently, the plant is considered endangered in its natural habitat because of its destructive harvesting, habitat destruction, and deforestation. As it is a highly perishable commodity, it needs proper handling, preservation, and storage. This review will outline the medicinal properties, uses, value addition, and preservation techniques of asparagus roots. The study found that, till now, the only preservation techniques used to increase the shelf life of asparagus roots are drying and irradiation. © 2022 Society of Chemical Industry.

Mycotoxins along the tea supply chain: A dark side of an ancient and high valued aromatic beverage

ABSTRACTSTea (Camellia sinensis L.) is a high valued beverage worldwide since ancient times; more than three billion cups of tea are consumed each day. Leaf extracts of the plant are used for food preservation, cosmetics, and medicinal purposes. Nevertheless, tea contaminated with mycotoxins poses a serious health threat to humans. Mycotoxin production by tea fungi is induced by a variety of factors, including poor processing methods and environmental factors such as high temperature and humidity. This review summarizes the studies published to date on mycotoxin prevalence, toxicity, the effects of climate change on mycotoxin production, and the methods used to detect and decontaminate tea mycotoxins. While many investigations in this domain have been carried out on the prevalence of aflatoxins and ochratoxins in black, green, pu-erh, and herbal teas, much less information is available on zearalenone, fumonisins, and Alternaria toxins. Mycotoxins in teas were detected using several methods; the most commonly used being the High-Performance Liquid Chromatography (HPLC) with fluorescence detection, followed by HPLC with tandem mass spectrometry, gas chromatography and enzyme-linked immunosorbent assay. Further, mycotoxins decontamination methods for teas included physical, chemical, and biological methods, with physical methods being most prevalent. Finally, research gaps and future directions have also been discussed.

Temporal depletion of packaged tea antioxidant quality under commercial storage condition

Shelf life studies play a significant role in determination of time duration for the retention of product quality after packaging. Assessment of tea shelf life in terms of antioxidant quality, a prime health benefit trait of tea would substantiate its marketing and consumption preference to the trade and end users. In shelf life analysis of tea with respect to its antioxidant potentialities, both antioxidant activity and incidences of secondary metabolites are responsible. A temporal analysis with regular intervals since 1 year of said characteristics has been carried out in four types of processed teas. To be precise, the overall initial antioxidant concentrations and activities were almost maintained up to 90-120 days and thereafter declination appeared. Beyond 180 days, rapid declination occurs and beyond 330 days, depletion recorded up to 60-75% of the initial activity. Black tea showed maximum ferrous ion chelating activity initially and white tea commenced with slight lower value but it maintained a similar trend up to 150 days while a rapid declination occurred in such activity of black and green tea after 30 days only. It is observed that total tannins or proanthocyanidins amount highest in white tea among all other three types. The preservation of metal chelating activity of white tea was observed as comparable to its stability in tannin composition (r² = 0.869, P ≤ 0.01) during the storage period.

The influence of processing on the microbial risk associated with Rooibos (Aspalathus linearis) tea

This review discusses the influence of processing on the microbial risk associated with Salmonella in Rooibos tea, the identification of Salmonella and preventative and control measures to control microbial contamination. Rooibos tea, like other plant products, naturally contains a high microbial load. Downstream processing steps of these products usually help in reducing any contaminants present. Due to the delicate flavour properties and nature of Rooibos, gentle processing techniques are necessary for the production of good quality tea. However, this has a major influence on the microbiological status of the product. The presence of Salmonella in Rooibos is poorly understood. The ubiquitous distribution of Salmonella in the natural environment and its prevalence in the global food chain, the physiological adaptability, virulence of the bacterial pathogen and its serious economic impact on the food industry, emphasises the need for continued awareness and stringent controls at all levels of food production. With the advances of technology and information at hand, the processing of Rooibos needs to be re-evaluated. Since the delicate nature of Rooibos prohibits the use of harsh methods to control Salmonella, alternative methods for the steam pasteurisation of Rooibos show great potential to control Salmonella in a fast, efficient and cost-effective manner. These alternative methods will significantly improve the microbiological quality of Rooibos and provide a product that is safe to consumers.

Gamma irradiation of air-dried olive leaves: Effective decontamination and impact on the antioxidative properties and on phenolic compounds

Olive leaves are commercialized for their antioxidative value due to their valuable phenolic compounds. The present study aimed to evaluate the effect of gamma irradiation on microbial load, on antioxidative properties and on phenolic compounds of air-dried olive leaves. Irradiation was applied up to 25kGy (5kGy intervals) to powdered and intact samples. Total aerobic bacteria, yeast and mold, and lactic acid bacteria were counted after gamma irradiation. Decontamination was obtained at 20kGy. The radioresistance of microbial population was high with D10 values between 9.74 and 25.12kGy. Besides, gamma irradiation up to 25kGy was found to maintain the antioxidant capacity, molecular mass distribution of polyphenolics, total phenolics, ortho-diphenols, flavonoids, oleuropein, verbascoside and rutin contents. To conclude, the improvement of the microbial quality of air-dried olive leaves, without affecting phenolic composition and antioxidative properties, can be successively achieved by the application of gamma irradiation treatment.

Quality index of oils extracted from gamma-irradiated peanuts (Arachis hypogaea L.) of the golden and bari varieties

Two varieties of peanuts were irradiated to 4, 6 and 8 kGy with Co(60). Their proximate compositions remained unaffected, but microbes were eliminated completely after irradiation to 8 kGy. HPLC was used to study tocopherols of irradiated and unirradiated oil samples. There were dose-dependent differences in physico-chemical values between the control and irradiated samples. Significant changes in tocopherol concentrations and peroxide values in the oils were observed after irradiation to 8 kGy. Fatty acid compositions did not change significantly. The study has shown that irradiation is an effective tool in preservation of peanut oil.