Sustainable production of astaxanthin from Dilocarcinus pagei crab and optimisation of its extraction with edible oils.

Dilocarcinus pagei is a South American crab commonly found in fishponds. As crabs are a source of astaxanthin (AST) and food inputs, this preliminary research aimed at studying the composition of females and males of this species to assess its potential for commercial applications, and at optimising the extraction of AST with edible oils to promote its use as an ingredient for the nutraceutical, pharmaceutical and feed industries. The chemical composition differed between males and females only in moisture, and the values obtained were: 65.4 ± 1.0% and 72.5 ± 3.1% moisture, 45.7-40.3% d.m. minerals, 22.0-24.1% d.m. fibres, 18.2-17.4% d.m. proteins, and 10.4-11.1% d.m. lipids. The Box-Behnken design was applied and validated for extraction with soya bean and sunflower oils, adjusting the oil:crab ratio, temperature, and extraction time. The optimal conditions found consisted of 140 mL/g, 90 °C and 170 min for soya bean oil, reaching an accumulation of AST of 50 ± 5 µg/g crab d.m. For sunflower oil, the conditions were 60 mL/g, 90 °C and 161 min, reaching 31 ± 3 µg/g crab d.m. Finally, the amounts of AST obtained using soya bean oil were higher than those obtained using sunflower oil; thus, soya bean oil would be recommended as a solvent to extract the pigment.

Citrus flavonoids against Fusarium verticillioides in post-harvest maize: Minimization of fumonisins and alteration of fungal ultrastructure.

AIMS: To minimize fumonisins (FBs) accumulation by Fusarium verticillioides in post-harvest maize, using flavonoids obtained from citrus residues: naringin (NAR), neohesperidin (NEO), quercetin (QUER), and its mixtures. METHODS AND RESULTS: Response surface methodology with Box-Behnken design was applied in maize at 0.98 and 0.95 aw . The optimal mixture found, composed of 0.40 mmol kg-1  NAR, 0.16 mmol kg-1  NEO and 0.37 mmol kg-1 QUER, reduced the accumulation of FBs B1, B2, and B3 by 88 ± 6%, 90 ± 6% and 85 ± 5%, respectively, when applied to maize at 0.98 aw . The mentioned mixture led to a 54 ± 9% reduction of fumonisin B1 accumulation in maize adjusted to 0.95 aw . These flavonoids applied individually and as a mixture, affected the structure of both the cell wall and the cytoplasm of F. verticillioides. The cell wall lost rigidity and the cells appeared highly deformed, with ruptured plasmalemma and disrupted endomembranes. CONCLUSIONS: It was possible to diminish the accumulation of FBs in maize by a highly toxigenic Fusarium strain, producing severe damage to its ultrastructure. SIGNIFICANCE AND IMPACT OF STUDY: The results indicate the possible use of flavonoids from citrus industry residues as natural and environmentally friendly antifungal agents to restrain the accumulation of FBs in stored maize.

Evaluation of citrus flavonoids against Aspergillus parasiticus in maize: Aflatoxins reduction and ultrastructure alterations.

In this study, the effects of citrus flavonoids naringin (NAR), neohesperidin (NEO) and quercetin (QUER) on aflatoxins accumulation by a selected Aspergillus parasiticus strain in maize at 0.95 aw were studied by response surface methodology using a Box-Behnken design. Multiple response optimization was applied to simultaneously minimize the contamination with aflatoxins (AFs) B1, G1, B2 and G2. The application of the optimal mixture in maize at 0.95 aw (0.39 mM NAR, 0.24 mM NEO and 0.40 mM QUER) reduced from 85% to 100% AFs accumulation. The same mixture at 0.98 aw, led to a reduction in AFs accumulation that ranged from 93% to 98%. Ultrastructure alterations of cellular membranes and walls in A. parasiticus, evidenced by transmission electron microscopy images, were severe and depended on the type of flavonoid and their combination. Flavonoid mixtures may provide an environmentally friendly alternative for decreasing AFs accumulation in stored maize, replacing synthetic compounds.

Aflatoxins distribution in fractions derived from tofu production.

Tofu or bean curd is obtained from soybean seeds being a widespread food product in Asia. The commodity used for its production can be contaminated with aflatoxins, which are secondary metabolites synthetised by species of Aspergillus flavus and A. parasiticus. Intake of contaminated food products causes toxic effects on consumers. The aim of this work was to study aflatoxin distribution in fractions obtained from pilot-scale tofu production with contaminated soybeans. The presence of the aflatoxins B1, B2, G1 and G2 (AFs) in soaking water, okara, whey and tofu was analysed. Aflatoxin analysis was performed by HPLC with fluorescence detection. The distribution of aflatoxins in all the analysed fractions was not a normal distribution. The liquid fractions (soaking water and whey) had less contamination than solid fractions (tofu and okara). The percentage AFB1 remaining in nutritionally important fractions, okara and tofu, was between 6.2% and 67.7% (median = 18.1%) and 0.5% and 13.2% (median = 3.5%), respectively. AFB2, AFG1 and AFG2 had a similar distribution. These results showed that throughout tofu production, AFs can be present in the products intended for human consumption.