Sorghum is the fifth cereal most produced in the world after wheat, rice, maize, and barley. In some regions, this crop is replacing maize, due to its high yield, resistance to drought and heat. There are several varieties of sorghum, whose coloration varies from cream, lemon-yellow, red, and even black. Pigmented sorghum grain is a rich source of antioxidants like polyphenols, mainly tannins, which have multiple benefits on human health such as, antiproliferative properties associated with the prevention of certain cancers, antioxidant activities related to the prevention of associated diseases to oxidative stress, antimicrobial and anti-inflammatory effects, it also improves glucose metabolism. Despite having these types of compounds, it is not possible to assimilate them, their use in the food industry has been limited, since sorghum is considered a food of low nutritional value, due to the presence of anti-nutritional factors such as strong tannins which form complexes with proteins and iron, thus reducing their digestibility. Based on these restrictions that this product has had as food for humans, the analysis of this review emphasizes the valorization of sorghum as a source of bioactive substances and the importance they confer on human health because of the biological potential it has.

Prickly pear peel (Opuntia ficus-indica) residues can be used as a substrate in solid-state fermentation to obtain bioactive compounds. The kinetic growth of some Aspergillus strains was evaluated. A Box–Hunter and Hunter design to evaluate the independent factors was used. These factors were temperature (°C), inoculum (spores/g), humidity (%), pH, NaNO₃ (g/L), MgSO₄ (g/L), KCl (g/L), and KH₂PO₄ (g/L). The response factors were the amount of hydrolyzable and condensed tannins. The antioxidant and antimicrobial activity of fermentation extracts was evaluated. Aspergillus niger strains GH1 and HT3 were the best for accumulating tannins. The humidity, inoculum, and temperature affect the release of hydrolyzable and condensed tannins. Treatment 13 (low values for temperature, inoculum, NaNO₃, MgSO₄; and high values for humidity, pH, KCl, KH₂PO₄) resulted in 32.9 mg/g of condensed tannins being obtained; while treatment 16 (high values for all the factors evaluated) resulted in 3.5 mg/g of hydrolyzable tannins being obtained. In addition, the fermented extracts showed higher antioxidant activity compared to the unfermented extracts. Treatments 13 and 16 showed low inhibition of E. coli, Alternaria sp., and Botrytis spp. The solid-state fermentation process involving prickly pear peel residues favors the accumulation of condensed and hydrolyzable tannins, with antioxidant and antifungal activity.

Currently, agroindustrial waste can be used to obtain bioactive compounds. The solid-state fermentation is an alternative for the valorization of these waste and to be able to release bioactive compounds that may be of interest to different industrial sectors. The aim of this study was to evaluate solid-state fermentation conditions using pineapple peel waste as the substrate with Aspergillus niger spp., to release bioactive compounds using a Plackett–Burman exploratory design. Temperature, humidity, inoculum, NaNO₃, MgSO₄, KCl, and KH₂PO₄ conditions in the fermentation process were evaluated. The antioxidant capacity was determined, and the main compounds of the fermentation extracts were identified. The results revealed that the Aspergillus niger HT3 strain reached a hydrolyzable tannin release of 10.00 mg/g, While Aspergillus niger Aa20 reached a condensed tannin release of 82.59 mg/g. The KH₂PO₄ affects the release of condensed tannins with A. niger Aa20, and MgSO₄ affects the release of hydrolyzable tannins with A. niger HT3. In addition, a positive antioxidant activity was demonstrated for the DPPH, ABTS, and FRAP technique. The main compounds in the fermented pineapple peel were 3-feruloylquinic acid, caffeic acid, lariciresinol, and 3-hydroxyphloretin 2′-O-xylosyl-glucoside, among others. The solid-state fermentation process is a biotechnological alternative for the release of bioactive compounds.

The strawberry fruit (Fragaria × ananassa Duch.) is appreciated for its aroma, color, texture and nutritional value. In conventional agriculture, the use of fertilizers damages the environment since it causes loss of soil fertility, salinity and its erosion, hence production alternatives, without harming the environment, are sought. The objective of this study was to evaluate the effect of a biostimulant based on humic substances and rhizobacteria, on the production and quality of the strawberry cultivar ‘San Andreas’. Strawberry plants cultivar ‘San Andreas’ were treated with fulvic acids + mixture of microorganisms, humic acids + Pseudomonas fluorescens, fulvic acids + Azospirillum brasilense, fulvic acids + Pseudomonas fluorescens and the mixture AH and AF + Azospirillum brasilense with two doses (d1, d2) in total 10 treatments were applied plus the control. Humic substances were applied every 15 days and rhizobacteria every 30 days. The results showed that the AFyAzoz d1 increased over control plants, the number of leaves in 38.3%, root volume in 42.6%, the fresh weight in 130% and dry weight in 63.8%, the number of fruits 50.0% and the yield in 59.5%. The AFyPF d1 favored Photosynthesis in 127.3%; AFyPF d1 increased TSS in 25%, AFyPF d2 vitamin C in 17.1% and MHyF + Azoz d1 increased in 20% the content of Phenols. Humic substances plus rhizobacteria are an ecological alternative to be used as biostimulant in the production and quality of strawberry plants.

The Opuntia ficus-indica (OFI) prickly pear peel, is a residue product and was used as a substrate in solid-state fermentation (SSF) to obtain bioactive compounds of interest due to its antimicrobial and antioxidant activity. A Box Hunter & Hunter design to evaluate the independent factors was used. These factors were temperature (°C), inoculum (spores/g), humidity (%), pH, NaNO3 (g/L), MgSO4 (g/L), KCl (g/L) and KH2PO4 (g/L). The response factors were hydrolyzable and condensed tannins amount. In addition, the fermentation extracts the antioxidant and antimicrobial activity were evaluated. The results showed that the humidity (%), inoculum (spores/g) and temperature (°C) affect the release of hydrolyzable and condensed tannins. The treatments 13 and 16 were the best to accumulate condensed (43 mg/g) and hydrolyzable tannins (3.8 mg/g) respectively. Besides, the fermented extracts showed a higher antioxidant activity compared than the unfermented peel extracts, as well as a high inhibition versus E. coli, Alternaria sp. and Botrytis spp. The use of the fermentation process is a good alternative for the recovery of waste and the accumulation of bioactive molecules with potential industrial application.

A good strategy to prevent early deposition of bacteria that can form biofilms is the application of antimicrobial coatings to existing surfaces, however this field has been little explored and coatings are often non uniform in thickness. A homogeneous film of R-Carvone-Octadiene (ppCop) was deposited on different substrates (coverslip, minced coverslip and fabric) by cold plasma copolymerization to study the influence of the substrate on antimicrobial activity and show clues about the influence of octadiene on copolymerization. The ppCop showed better antimicrobial activity results on the substrate with higher effective contact area, highlighting the influence of this variable on antimicrobial activity. The ppCop deposited on minced coverslip showed an inhibition of E. coli and S. aureus bacteria by 48.69 ±0.08% and 49.31 ±0.58% respectively, with an average roughness of 14.1±0.02 nm and a static water contact angle of 79± 0.4°. The ppCop showed no cytotoxicity to the human cell line.