In this present study, the efficiency of ultrasound-assisted extraction (UAE) in increasing the yields of extraction of starch and polyphenols from Canna indica L. (Canna) rhizomes were analyzed, along with its influence on the physiochemical properties of the extracted compounds. Extraction parameters (temperature, time, and solid-to-liquid ratio) were optimized through Box–Behnken response surface design (BBD). The physiochemical and functional properties of starch and polyphenols were investigated through scanning electron microscopy (SEM), the swelling and solubility index, oil and water absorption index, total polyphenol yield, and antioxidant activity assays (DPPH and ORAC). The starch yield obtained from Canna at the optimum extraction conditions (temperature 40 °C, time 10 min, and solid-to-liquid ratio 1:30 g/mL) was 19.81%. The obtained starch yield was found to be significantly higher than the yield attained through the conventional extraction method without adverse changes in the physicochemical and functional properties. The total polyphenol extraction yield from the Canna rhizome, through UAE, was significantly higher (1061.72 mg GAE/100 g) than that of the conventional method. The antioxidant activity of bioactive compounds was proportional to the attained polyphenol yield. Our results suggest that UAE optimized conditions efficiently and improved Canna starch and polyphenol extraction yields while preserving their functional properties.

Haematococcus lacustris is a freshwater green microalgae species able to produce and accumulate astaxanthin in response to environmental stresses such as high light and nutrient deprivation. Astaxanthin is a xanthophyll carotenoid of growing economic interest due to its numerous biological activities, notably its strong antioxidant properties, which can be valued in the fields of nutrition, health, feed and aquaculture. The present study aims at evaluating the capacity of two newly isolated Haematococcus strains from the biodiversity of Reunion Island, to be cultivated in a photobioreactor and to produce astaxanthin. The results showed that both strains were able to grow in various nutritive media and to produce and accumulate astaxanthin in response to stresses, mainly in the form of astaxanthin monoesters, which represented up to 2% of the dry biomass weight and which were mostly composed of linoleic and linolenic acids. In fed-batch cultures using 3 L benchtop photobioreactors, the concentrations of biomass enriched in astaxanthin reached up to 3 g L−1 (dry weight) with biomass productivities of 0.04 and 0.02 g L−1 d−1 based on the durations of the vegetative stage and of the entire culture, respectively. In these cultures, the astaxanthin productivities were found to reach on average around 0.25 mg L−1 d−1. Although these results were relatively low compared to the literature, the possibility of improving growth conditions in order to improve biomass and astaxanthin yields, to guarantee economic viability for cultivation at a commercial scale, was further discussed.

Certain secondary carotenoids, such as astaxanthin and canthaxanthin, are of growing economic interest in the fields of human nutrition, food, health and cosmetics, as well as feed and aquaculture, particularly due to their numerous biological activities, such as their remarkable antioxidant properties. The present study was devoted to assessing, in a photobioreactor, the feasibility of cultivating newly isolated Dysmorphococcus strains from the biodiversity of Reunion Island for the production of these valuable xanthophylls. The results showed that all these strains were capable of producing and accumulating canthaxanthin and astaxanthin in response to environmental stresses. Among them, a strain which presented interesting morphological, genetic and biochemical properties as compared to the other Dysmorphococcus strains was further cultivated in a 3 L benchtop photobioreactor and was found to produce maximum carotenoid-rich biomass concentrations and productivities of about 4 g L−1 dw and 0.055 g L−1 d−1 dw, respectively. We also found that the biomass contained up to 1.2 mg g−1 dw of canthaxanthin and 0.7 mg g−1 dw of different forms of astaxanthin, mainly astaxanthin monoesters. The productivity of these carotenoids was found to be lower than those observed for other microalgal species previously reported, and we suggested that further optimizations with respect to the cultivation and the carotenogenesis induction processes are needed to improve productivities and to make this locally isolated Dysmorphococcus strain useful for future commercial production of natural canthaxanthin and astaxanthin.

Manihot esculenta (cassava) roots is a major food crop for its energy content. Leaves contain nutrients and demonstrate biological properties but remain undervalorized. In order to develop a bioguided optimization of cassava nutrition–health properties, we compared the phytochemistry and bioactive potential of cassava root flour extract (CF) with cassava flour extract enriched with 30% leaves powder (CFL). Cassava flour supplementation impact was explored on flour composition (starch, fiber, carotenoids, phenolic compounds), in vivo glycemic index, and bioactivity potential using macrophage cells. We assessed the impact of cassava flour supplementation on free radicals scavenging and cellular production of pro-inflammatory mediators. CFL showed higher levels of fiber, carotenoids, phenolic compounds, and lower glycemic index. Significantly higher bioactive properties (anti-inflammatory and antioxidant) were recorded, and inhibition of cytokines production has been demonstrated as a function of extract concentration. Overall, our results indicate that enrichment of cassava flour with leaves significantly enhances its nutrition–health and bioactive potential. This bioguided matrix recombination approach may be of interest to provide prophylactic and therapeutic dietary strategy to manage malnutrition and associated chronic non-communicable diseases characterized by low-grade inflammation and unbalanced redox status. It would also promote a more efficient use of available food resources.

Madagascar is a world hotspot of biodiversity, with an endemism rate that reach up to 80%. Therefore, its flora represents a potential reservoir for bio-compounds, the development of which represents a scientific, an economic as well as an environmental challenge. Today, the harmfulness of petrochemical dyes to both human health and the environment is established. An alternative relies on the production of natural dyes trough green chemistry processes. Our research, based on indigenous empirical knowledge of dyers at Madagascar (in Indian Ocean), proposes as a first step to record all Malagasy dye plant species through an ethnobotanical survey and chemical screening of the coloration potential of some plant extracts. In a second step, the most interesting plant extracts (in aqueous ethanolic solution) were selected for a more indepth characterization of the color properties of the raw extracts. Several Malagasy plants species have been identified to have promising coloration potential as alternative sources of dyes or pigments. Two sources of natural yellow and two sources of natural red dyes will be discussed in this study. The plant biomass includes barks of Acridocarpus excelsus and Harungana madagascariensis, leaves of Tectona grandis and roots of Paracarphalea kirondron. The main chemical families identified in these four plant extracts are polyphenols, flavonoids, tannins, xanthonoids and quinonoids. Most of the pigments extracted from these five plants showed very good stability toward pH and high temperatures (up to 200 degrees C). Moreover, some plant extracts also showed high antioxidant and antimicrobial properties. Finally, an acute toxicity test performed using a zebrafish model showed that most of these extracts are less toxic than the usual artificial dyes. It should be noted that very little information has been found in the literature about the composition of roots of the endemic species P. kirondron. HPCL/DAD/MS analysis of the yellow colors extracted from P. kirondron showed a high concentration of different quinonoid pigments with potentially new structures (research in progress in laboratory). The diversity of dye plants from Madagascar is a promising source of natural dyes that can replace the artificial ones. However, the supply of a production chain for these dyes involves the respect for the rights of local actors and the implementation of actions to manage this biodiversity in a sustainable way.

Sweet potato (SP), Ipomoea batatas Lam, belongs to the Convolvulaceae family. It produces edible storage roots. Currently, orange varieties contribute to improving food systems and managing vitamin A deficiency. Processing of this food crop into flour allows better conservation. However, nutrition health data regarding SP flour obtained by green extraction remains scarce. In this study, we therefore explored its phytochemistry and its associated bioactivity potential for human health. We analyzed the nutritional composition of orange flesh sweet potato (OFSP) flour and assessed the antioxidant (free radical scavenging) and immunomodulatory (on inflammatory murine macrophages) properties of the extract. More specifically, we measured the impact of OFSP flour extract on mediators such as Nitric Oxide (NO) and the production of pro-inflammatory cytokines such as Interleukin-6 (IL-6), Tumor Necrosis Factor alpha (TNF-alpha), Monocyte Chemoattractant Protein-1 (MCP-1), and Prostaglandin-E2 (PGE-2). Our results indicated significant fiber, mineral, beta-carotene, and polyphenols content in the extracts, and antioxidant and immunomodulatory bioactivities were also demonstrated with a concentration-dependent inhibition of cytokine production. Taken together, our results suggest that Ipomoea batatas flour could, in addition to being a good source of energy and beta-carotene provitamin A, constitute a food of interest for the prophylaxis of metabolic diseases associated with an underlying low-grade inflammatory state.

The search for alternative sources of colorants and pigments has been put forward over the last two decades in numerous industrial sectors such as textile, food, cosmetics and pharmaceuticals. Proven toxicity and environmental burdens caused by artificial dyestuffs have motivated industries to turn to natural colorants, and notably those originated from plants. Reunion island possesses a significant number of endemic plant species, as well as native and exotic species, which are rich in pigments of diverse hues. Through the "PLANTIN European project", conducted by the laboratory ChemBioPro (University of La Reunion), in collaboration with the "Conservatoire Botanique National de Mascarin" (CBNM), and several other partners from Reunion Island, a screening of the tropical plant biodiversity allowed the identification of several promising dye-producing local plant species. The importance of different physicochemical criteria such as the endemicity, the extracted colors, or plant parts used for the extraction process, among others, have been considered to establish a classification method of the inventoried dye-producing plant species to finally select for the most compelling species for dye application in industries. The Indian Ocean region still offers huge potential for discovering new sources of plant-based dyestuffs. These latter showed highly promising coloring and physicochemical properties, consequently offering versatile application possibilities and opening up new markets. Thus, there is no doubt this is the tip of the iceberg, and many other tropical plant species should be investigated to unveil myriad of other useful natural compounds.

Astaxanthin is a high value xanthophyll carotenoid with applications in the fields of nutrition and health in particular, due to its antioxidant properties among other bioactivities. Although synthetic astaxanthin is currently dominant in the global market, consumers increasingly prefer astaxanthin from natural sources for human applications. In this context, the production of natural astaxanthin could represent a great economic opportunity for insular territories such as Reunion Island to develop local alternatives to the importation of goods. The aim of this study was to search within the freshwater biodiversity of Reunion Island for strains of microalgae capable of producing and accumulating astaxanthin. During this study, 11 strains were isolated from freshwater samples collected throughout the island. These strains showed similar morphological characteristics with Haematococcus lacustris (Chlorophyceae, Chlamydomonadales, Haematococcaceae), a well-known algal species that is cultivated for industrial production of natural astaxanthin. Molecular and phylogenetic analyses allowed their genetic identification and revealed that these wild local strains belong to two different genera: Haematococcus and Dysmorphococcus (Chlorophyceae, Chlamydomonadales, Phacotaceae). Analysis of pigment extracts using High-Performance Thin Layer Chromatography and High-Performance Liquid Chromatography confirmed that the local strains of Haematococcus isolated were able to produce and accumulate astaxanthin under light and nutritional stress conditions. The local strains of Dysmorphococcus spp. were also able to produce astaxanthin. To our knowledge, this is the first time that these genera have been described in Reunion Island. The demonstration of the existence of local strains of Haematococcus is a promising first step toward the industrial production of natural astaxanthin in Reunion Island. Additionally, Dysmorphococcus spp. could represent an alternative source for high value carotenoids.

Background Proven toxicity and environmental burdens caused by artificial dyes have motivated dyeing industries to turn to natural alternatives. Plant-based dyestuffs are an interesting group of alternative crops. Reunion Island located in the Indian Ocean is the only European region in the southern hemisphere. It has a great number of assets to find new molecules in the abundant plant biodiversity. However, the dye-producing plants diversity in this island had not been documented to date. Methodology The assessment of the Reunion Island’s plant biodiversity through the “PLANTIN” project allowed us to establish here the first ethnobotanical inventory of plants growing on Reunion Island which may have promising properties as a new alternative source of dyes or colorants for the industries. First, an ethnobotanical survey focused on the uses of plants traditionally used in dyeing was conducted on local stakeholders. Then, the importance of different criteria ( e.g. , endemicity, accessibility and cultivability, plant organs used for the extraction, industrial interests of the species, etc.) has been considered to establish a classification method of the species, to finally select the most interesting plants which have been further harvested and investigated for their coloring property and dyeing application on natural fibers. Results The results showed that local people have accumulated traditional knowledge of dyeing plants, but that this approach had been discontinued in Reunion. The uses of 194 plant species potentially rich in dyes or pigments, belonging to 72 different families, with diverse botanical status (endemic, native, introduced or alien-invasive species) have been recorded. Then, 43 species were harvested and their coloring property were investigated. It demonstrated that dyes extracted from promising species, e.g ., Terminalia bentzoe, Weinmannia tinctoria, Thespesia populnea, Erythroxylum laurifolium, Morinda citrifolia, Leea guinensis, Ochrosia borbonica, Danais fragrans, Terminalia cattapa, Casuarina equisetifolia, and Coccoloba uvifera , amongst others, could be used as new textile dyes. Their efficacy in the wool and cotton dyeing has been successfully demonstrated here. Conclusion These plant-based dyestuffs showed promising coloring properties with different shades that could meet industrial application requirement. It's an area that could promote local cultural inheritance, create opportunity for business and farmers, and that can make a significant contribution to preserving endangered native species by supporting reforestation schemes. Additional researches are in progress to evaluate the safety of these plant-based colored extracts, their chemical composition and biological activities.

α-unsaturated esters are fruity-aromatic compounds which are largely spread in the volatilome of many different fruits, but they are rarely found in the volatilome of yeasts. The yeast S. suaveolens has been recently shown to produce relatively high amounts of α-unsaturated esters and it appears to be an interesting model for the production of these compounds. This study aimed to isolate new α-unsaturated ester-producing yeasts by focusing on strains displaying a similar metabolism to S. suaveolens. While the production of α-unsaturated esters by S. suaveolens is believed to be closely related to its ability to grow on media containing branched-chain amino acids (isoleucine, leucine and valine) as the sole carbon source (ILV+ phenotype), in this study, an original screening method was developed that selects for yeast strains displaying ILV+ phenotypes and is able to produce α-unsaturated esters. Among the 119 yeast strains isolated from the feces of 42 different South African wild animal species, 43 isolates showed the ILV+ phenotype, among which 12 strains were able to produce α-unsaturated esters. Two interesting α-unsaturated esters were detected in two freshly isolated strains, both identified as Galactomyces candidus. These new esters were detected neither in the volatilome of the reference strain S. suaveolens, nor in any other yeast species previously studied for their aroma production. This work demonstrated the efficiency of an original method to rapidly screen for α-unsaturated ester-producing yeasts. In addition, it demonstrated that wild animal feces are interesting resources to isolate novel strains producing compounds with original aromas.

Vanilla flavor is derived from the cured fruits of two orchid species Vanilla planifolia and V. × tahitensis. About twenty other Vanilla species are also credited with scented fruits, but very little is known about their aromatic features. We investigated the aromatic compound content of the ripe fruits of 30 vanilla accessions obtained from eight species and three hybrids. Glucovanillin plus six phenolic and one anisic aglycones, extracted after enzymatic hydrolysis, were quantified by High-Performance Liquid Chromatography and Ultra-Violet detection. The analysis of the aromatic contents and the principal components showed clear-cut differences in the aromatic content of the species and varieties studied. The total content of aromatic compounds separated the three species most distantly related to V. planifolia, namely V. lindmaniana, V. crenulata and V. imperialis, from the other species notably by the absence of vanillin potential and a very low total aromatic potential (< 0.45% w/w dry matter). A clear gradient was observed between the different genotypes of V. planifolia, in particular for the total aromatic content (range 3.07–5.00% dry weight) and the vanillin potential (1.80–4.58%). Among all the analyzed samples, the greatest vanillin potential was observed in a V. planifolia x V. × tahitensis hybrid (7.46%). Anisyl alcohol was not detected in any of the 13 V. planifolia varieties but was detected in most of its close relatives such as V. sotoarenasii, V. bahiana, V. tahitensis, and V. pompona. Our data evidenced the very contrasting aromatic profiles of vanilla fruits, even among very close genotypes.

Fruity beers can be promoted through production of flavoring compounds during fermentation by partial replacement of brewing yeast by non-conventional-yeasts with high aroma production abilities. We evaluated here the use of a wild Saprochaete suaveolens strain, producing atypical aroma compounds, to produce new natural fruity beer, while keeping classical production conditions used in brewing industry. S. suaveolens was inoculated as starter of culture during beer fermentation and the fermentation performance was evaluated through measurement of several physicochemical parameters. The aroma profile of the engineered beers was monitored using HS-SPME GC/MS. The results showed that high fruity aroma and low-ethanol content beers were obtained through single-fermentation using S. suaveolens. We also demonstrated that during mixed-fermentation, S. suaveolens maintained high metabolic activity and allowed production of beer enriched with fruity aroma. Production of high or low ethanol content fruity beer could be achieved by varying the composition of the starter of culture.