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The pineapple leaves (PL) left over in the fields after pineapple harvest or burnt out, generate waste which contributes to the release of greenhouse gases. As pineapple is one of the most harvested crops in the world, the quantity of pineapple trash and its disposal methods are challenging. The composition of PL waste makes it unique to encounter the increasing demand for renewable energy and other useful products. This review is focused on the production of different biorefinery products and miscellaneous products from PL waste. The high cellulose content in PL makes it a potential feedstock for the production of different biorefinery products like bioethanol, oligosaccharides, nitrocellulose, and humic acid apart from this, waste is also useful for the production of different products like pineapple leaf fibres, fake eyelashes, organic leather, pulp and paper. Although the opportunities, future perspectives, and challenges concerning PL waste utilization to value-added goods were also addressed. It has been demonstrated that pineapple waste conversions lower waste creation, and the products produced by the conversion would promote the 'waste-to-wealth' notion. [ABSTRACT FROM AUTHOR]

The municipal authorities in developing nations face serious challenges in marigold flower garbage management. The primary issue is that they never are reused after prayers. Flower waste of Tagetes erecta, T. patula, and Calendula officinalis L. are commonly used for carotenoid and flavonoid extractions and, subsequently, used for incense stick and biogas production. Marigold plants are also used for phytoremediation during their growth stage. The lutein industry is booming due to its increasing market demand, expected to reach ~2121.2 billion tons by 2022, where marigolds are a major contributor globally. The process of isolating lutein from saponified marigold oleoresin yields a product with 70–85% purity. Lutein is a major xanthophyll (70–88%) of marigold petals, and a maximum of 21.23 mg/g of lutein was extracted. This review discusses the properties of selective marigold species, their compositions, and the extraction of different flavonoids and carotenoids, especially lutein. Moreover, different extraction methods of marigold lutein, the collection of marigold waste, and their subsequent utilization to derive several value-added products are discussed. Among physical treatments, ultrasonic-assisted extraction and enzymatic treatment with 5% solids loading were the maximum-yielding methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microalgal astaxanthin is a super antioxidant molecule used as dietary supplements. • It possesses multifold bioactivities than other carotenoids/artificial astaxanthin. • Microalgal carotenoid market is expected to reach million ∼$550 by the year 2025. • Microalgal carotenoids exhibit 2–10 folds higher bioactivity than synthetic pigments. Microalgae have emerged as the best source of high-value astaxanthin producers. Algal astaxanthin possesses numerous bioactivities hence the rising demand for several health applications and is broadly used in pharmaceuticals, aquaculture, health foods, cosmetics, etc. Among several low-priced synthetic astaxanthin, natural astaxanthin is still irreplaceable for human consumption and food-additive uses. This review highlights the recent development in production enhancement and cost-effective extraction techniques that may apply to large-scale astaxanthin biorefinery. Primarily, the biosynthetic pathway of astaxanthin is elaborated with the key enzymes involved in the metabolic process. Moreover, discussed the latest astaxanthin enhancement strategies mainly including chemicals as product inducers and byproducts inhibitors. Later, various physical, chemical, and biological cell disruption methods are compared for cell disruption efficiency, and astaxanthin extractability. The aim of this review is to provide a comprehensive review of advancements in astaxanthin research covering scalable upstream and downstream astaxanthin bioproduction aspects. [ABSTRACT FROM AUTHOR]