Quantitative analysis and recovery optimisation of flavonoids and anthocyanins in sugar-making process of sugarcane industry

Bioactive compounds as an alternative for the sugarcane industry: Towards an integrative approach

Here, a comprehensive review of sugarcane industrialization and its relationship with bioactive compounds (BCs) detected in various products and by-products generated during its processing is presented. Furthermore, it is discussed how these compounds have revealed important antioxidant, antineoplastic, antidiabetic, and antimicrobial activities. From this bibliographic research highlights the significance of two types of BCs of natural origin (phenolic compounds (PCs) and terpenoids) and a group of compounds synthesized during industrial transformation processes (Maillard reaction products (MRPs)). It was found that most of the studies about the BCs from sugarcane have been conducted by identifying, isolating, and analyzing ones or a few compounds at a specific period, this being a conventional approach. However, given the complexity of the synthesis processes of all these BCs and the biological activities they can manifest in a specific biological context, novel approaches are needed to address these analyses holistically. To overcome this challenge, integrating massive and multiscale methods, such as omics sciences, seems necessary to enrich these studies. This work is intended to contribute to the state of the art that could support future research about the exploration, characterization, or evaluation of different bioactive molecules from sugarcane and its derivatives.

Enhanced cellulosic d-lactic acid production from sugarcane bagasse by pre-fermentation of water-soluble carbohydrates before acid pretreatment

After several rounds of milling process for sugars extraction from sugarcane, certain amounts of water-soluble carbohydrates (WSC) still remain in sugarcane bagasse. It is a bottleneck to utilize WSC in sugarcane bagasse biorefinery, since these sugars are easily degraded into inhibitors during pretreatment. Herein, a simple pre-fermentation step before pretreatment was conducted, and 98 % of WSC in bagasse was fermented into d-lactic acid. The obtained d-lactic acid was stably preserved in bagasse and 5-hydroxymethylfurfural (HMF) generation was sharply reduced from 46.0 mg/g to 6.2 mg/g of dry bagasse, after dilute acid pretreatment. Consequently, a higher d-lactic acid titer (57.0 g/L vs 33.2 g/L) was achieved from the whole slurry of the undetoxified and pretreated sugarcane bagasse by one-pot simultaneous saccharification and co-fermentation (SSCF), with the overall yield of 0.58 g/g dry bagasse. This study gave an efficient strategy for enhancing lactic acid production using the lignocellulosic waste from sugar industry.

Influence of phenolic acids/aldehydes on color intensification of cyanidin-3-O-glucoside, the main anthocyanin in sugarcane (Saccharum officinarum L.)

Sugarcane contains various anthocyanins, which are responsible for the colors present in sugarcane. In this study, the color intensification of the major anthocyanin, cyanidin-3-O-glucoside, by phenolic acids/aldehydes (ferulic acid, vanillic acid, p-coumaric acid, syringic aldehyde and vanillic aldehyde) was investigated. The color enhancement of cyanidin-3-O-glucoside (hyperchromic effect and bathochromic shift) was affected by the temperature and concentration of phenolic acids/aldehydes present. Reactions were spontaneous and exothermic, as determined using different thermodynamic parameters (ΔG⁰, ΔH⁰, ΔS⁰). Quantum chemical calculations demonstrated their intermolecular interaction differences, and AIM analysis indicated that hydrogen bonds and van der Waals force interactions contributed to color. Pyranoanthocyanins derived from cyanidin-3-O-glucoside and ferulic/p-coumaric acids during storage were recognized as cyanidin-3-O-glucoside-vinylphenol and cyanidin-3-O-glucoside-vinylguaiacol, respectively, by UPLC-ESI-QTOF-MS/MS. The electron-donating substituents on the aromatic ring of ferulic/p-coumaric acids stabilized the intermediately formed carbenium ion. Decarboxylation and further oxidation of the pyran moieties to the aromatic heterocycles resulted in the final products.

Recent trends in extraction of plant bioactives using green technologies: A review

Phenolic compounds from plant sources have significant health-promoting properties and are known to be an integral part of folk and herbal medicines. Consumption of phenolics is known to alleviate the risk of various lifestyle diseases including cancer, cardiovascular, diabetes, and Alzheimer's. In this context, numerous plant crops have been explored and characterized based on phenolic compounds for their use as supplements, nutraceutical, and pharmaceuticals. The present review highlights some important source of bioactive phenolic compounds and novel technologies for their efficient extraction. These techniques include the use of microwave, ultrasound, and supercritical methods. Besides, the review will also highlight the use of response surface methodology (RSM) as a statistical tool for optimizing the recoveries of the phenolic bioactives from plant-based matrices.

Immobilization of β-glucosidase onto silicon oxide nanoparticles and augment of phenolics in sugarcane juice

Purified β-glucosidase was immobilized on SiO₂ nanoparticles with 52 % efficiency and 14.1 % yield. It had a temperature optima at 60 °C and pH optima of 5.0. Immobilized enzyme was fairly stable at 60-70 °C. After immobilization, the K_m value of β-glucosidase for p-nitrophenyl-β-d-glucopyranoside (pNPG) increased from 0.9 to 1.074 mM and V_max decreased from 3.5 to 1.513 U/mg. The immobilized enzyme showed improved storage stability at temperature 4 and 25 °C and was reusable for up to ten cycles with 70 % residual activity in pNPG and 60 % residual activity in sugarcane juice treatment. Sugarcane juice density, viscosity; surface tension etc. changed after treatment with immobilized β-glucosidase. β-Glucosidase treated sugarcane juice showed higher phenolics than untreated sugarcane juice. Caffeic acid which was absent in juice, was detected in β-glucosidase treated juice at a concentration of about 1 mg/L.

Hollow fibre liquid phase micro-extraction by facilitated anionic exchange for the determination of flavonoids in faba beans (Vicia faba L.)

INTRODUCTION

Flavonoids are polyphenolic compounds found ubiquitously in foods of plant origin. They are commonly extracted from plant materials with ethanol, methanol, water, their combination or even with acidified extracting solutions. The disadvantages of these methods are the use of high quantity of organic solvent, the possible loss of analytes in the different steps and the laborious process of the techniques. In addition, the complexity of the phenolic mixtures present in plant materials requires a preliminary clean-up and fractionation of the crude extracts.

OBJECTIVE

To develop a hollow fibre liquid phase micro-extraction (HF-LPME) method for a one step clean-up and pre-concentration of flavonoids.

METHODOLOGY

Two flavonoids (catechin and rutin) has been extracted by HF-LPME and analysed by HPLC. The related driving force for the liquid membrane has been studied by means of facilitated and non-facilitated transport. Different ionic and non-ionic water insoluble compounds [trioctylamine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) and methyltrioctylammonium chloride (aliquat 336)] were used as carriers. The liquid membrane was constituted by a solution of n-decanol in the presence or absence of carriers.

RESULTS

Maximum enrichment factors were obtained with n-decanol/aliquat 336 (20%) as organic liquid membrane, sodium hydroxide (NaOH) (0.1 M) as donor solution, sodium chloride (NaCl) (2 M) as acceptor solution and 3 h as extraction time. Under these conditions, good results for validation parameters were obtained [for linearity, limit of detection (LOD), limit of quantitation (LOQ) and repeatability].

CONCLUSIONS

The developed method is simple, effective and has been successfully applied to determine catechin and rutin in ethanolic extracts of faba beans.

Sugar cane stillage: a potential source of natural antioxidants

Biorefinery of sugar cane is the first economic activity of Reunion Island. Some sugar cane manufactured products (juice, syrup, molasses) have antioxidant activities and are sources of both phenolic compounds and Maillard Reaction Products (MRP). The study aimed to highlight the global antioxidant activity of sugar cane stillage and understand its identity. Chromatographic fractionation on Sephadex LH-20 resin allowed the recovery of a MRP-rich fraction, responsible for 58 to 66% of the global antioxidant activity according to the nature of the sugar cane stillage (DPPH test), and a phenolic compounds-rich fraction for 37 to 59% of the activity. A good correlation was recorded between the antioxidant activity of the sugar cane stillage and its content in total reducing compounds amount (Folin-Ciocalteu assay), among them 2.8 to 3.9 g/L of phenolic compounds (in 5-caffeoylquinic acid equivalent). Preliminary experiments by HPLC-DAD-MS allowed to identify several free phenolic acids and gave clues to identify esters of quinic acids.

Protective effect of anthocyanins from lingonberry on radiation-induced damages

There is a growing concern about the serious harm of radioactive materials, which are widely used in energy production, scientific research, medicine, industry and other areas. In recent years, owing to the great side effects of anti-radiation drugs, research on the radiation protectants has gradually expanded from the previous chemicals to the use of natural anti-radiation drugs and functional foods. Some reports have confirmed that anthocyanins are good antioxidants, which can effectively eliminate free radicals, but studies on the immunoregulatory and anti-radiation effects of anthocyanins from lingonberry (ALB) are less reported. In this experiment, mice were given orally once daily for 14 consecutive days before exposure to 6 Gy of gamma-radiation and were sacrificed on the 7th day post-irradiation. The results showed that the selected dose of extract did not lead to acute toxicity in mice; while groups given anthocyanins orally were significantly better than radiation control group according to blood analysis; pretreatment of anthocyanins significantly (p < 0.05) enhanced the thymus and spleen indices and spleen cell survival compared to the irradiation control group. Pretreatment with anthocyanins before irradiation significantly reduced the numbers of micronuclei (MN) in bone marrow polychromatic erythrocytes (PCEs). These findings indicate that anthocyanins have immunostimulatory potential against immunosuppression induced by the radiation.