Enzymatic potential for the valorization of agro-industrial by-products.

Agro-industrial residues and by-products are a crescent environmental problem since they are often discarded without proper treatment, and still have growing production. These residues are rich from a nutritional point of view and contain various industrial relevant compounds, such as phenolic compounds, fibers, vitamins, sugars and others. The crescent worrying about environmental issues has led researchers and industries to focus on "eco-friendly" solutions for everyday problems. In this sense, the use of enzymes for the valorization of agro-industrial residues is a safe and green alternative technology. Hence, this review aims to show the enzyme potential for the use and valorization of several agro-industrial residues, focusing on the most produced residues worldwide, such as fruits, grains and lignocellulosic residues, as well as a brief explanation of microbial enzymes, its production and optimization, altogether with tools to identify producing microorganisms.

Intake, digestibility, microbial protein production, and nitrogen balance of lambs fed with sorghum silage partially replaced with dehydrated fruit by-products.

The objective of this study was to evaluate intake, digestibility, microbial protein production, and nitrogen balance of lambs fed with different dehydrated fruit residues replacing sorghum silage. The experiment was conducted using 25 mixed-breed male lambs (20.64 ± 4.20 kg) with an average age of 8 months. Treatments consisted of sorghum silage and 75% (DM basis) replacement of sorghum silage for dehydrated pineapple, banana, mango, or passion fruit by-products. The experiment was conducted in a completely randomized design with five treatments and five repetitions. Results were subjected to one-way analysis of variance and means were compared using the Tukey test at 5% of probability. Daily nutrient intake did not differ (P > 0.05) between the different treatments evaluated regardless of how it was expressed (kg/day or % body weight [BW]), except for NDFap (% BW) that was higher (P < 0.05) in the diet with passion fruit residue than in diets with banana and mango residues. The digestibility of ethereal extract was higher (P < 0.05) for diets with sorghum silage, pineapple, and passion fruit compared to the diet with banana residue. The digestibility of neutral detergent fiber corrected for ashes and protein was higher (P < 0.05) on animals receiving sorghum silage than diets with mango and passion fruit residues. No difference (P > 0.05) was observed for purine derivative excretion, microbial efficiency, nitrogen intake, nitrogen loss (urine and feces), and nitrogen balance between diets. In conclusion, dehydrated fruit by-products (pineapple, banana, mango, and passion fruit) are good options for partial replacement of sorghum silage (75%) and potentially reduce feeding costs.

Therapeutic and nutraceutical potential of bioactive compounds extracted from fruit residues.

The growing interest in the substitution of synthetic food antioxidants by natural ones has fostered research in identifying new low-cost antioxidants having commercial potential. Fruits such as mango, banana, and those belonging to the citrus family leave behind a substantial amount of residues in the form of peels, pulp, seeds, and stones. Due to lack of infrastructure to handle a huge quantity of available biomass, lack of processing facilities, and high processing cost, these residues represent a major disposal problem, especially in developing countries. Because of the presence of phenolic compounds, which impart nutraceutical properties to fruit residues, such residues hold tremendous potential in food, pharmaceutical, and cosmetic industries. The biological properties such as anticarcinogenicity, antimutagenicity, antiallergenicity, and antiageing activity have been reported for both natural as well as synthetic antioxidants. Special attention is focused on extraction of bioactive compounds from inexpensive or residual sources. The purpose of this review is to characterize different phenolics present in the fruit residues, discuss the antioxidant potential of such residues and the assays used in determination of antioxidant properties, discuss various methods for efficient extraction of the bioactive compounds, and highlight the importance of fruit residues as potential nutraceutical resources and biopreservatives.

Production of poly-3-hydroxybutyrate (PHB) nanoparticles using grape residues as the sole carbon source.

The production of poly-3-hydroxybutyrate (PHB) on an industrial scale remains a major challenge due to its higher production cost compared to petroleum-based plastics. As a result, it is necessary to develop efficient fermentative processes using low-cost substrates and identify high-value-added applications where biodegradability and biocompatibility properties are of fundamental importance. In this study, grape residues, mainly grape skins, were used as the sole carbon source in Azotobacter vinelandii OP cultures for PHB production and subsequent nanoparticle synthesis based on the extracted polymer. The grape residue pretreatment showed a high rate of conversion into reducing sugars (fructose and glucose), achieving up to 43.3 % w w-1 without the use of acid or external heat. The cultures were grown in shake flasks, obtaining a biomass concentration of 2.9 g L-1 and a PHB accumulation of up to 37.7 % w w-1. PHB was characterized using techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The formation of emulsified PHB nanoparticles showed high stability, with a particle size between 210 and 240 nm and a zeta potential between -12 and - 15 mV over 72 h. Owing to these properties, the produced PHB nanoparticles hold significant potential for applications in drug delivery.

Towards food circular economy: hydrothermal treatment of mixed vegetable and fruit wastes to obtain fermentable sugars and bioactive compounds.

Due to processing activity, fruits and vegetables generate notable amounts of wastes at the processing, retail, and consumption level. Following the European goals for reducing food wastes and achieving a circular economy of resources, these biowastes should be valorized. In this work, hydrothermal hydrolysis at different conditions (temperatures, times, waste/water ratio, pH values) were tested to treat for first time; biowastes composed of mixed overripe fruits or vegetables to maximize the extraction of fermentable sugars that can be used as substrates in bioprocesses. Experimental data were fitted by a model based on irreversible first-order reactions, and kinetic constants were obtained. When hydrolysis of fruit wastes was carried out at 135 °C and pH 5 during 40 min, more than 40 g of reducing sugars per 100 g of waste (dry weight) could be obtained (represents an extraction of 97% of total carbohydrates). Concentrations of inhibitor compounds (HMF, furfural, acetic acid) in the hydrolysates were very low and, as example, a fermentation to obtain bioethanol was successfully carried out with an efficiency above 95%. Additionally, the production by hydrothermal treatment of bioactive compounds was investigated and the best results obtained were 92% DPPH inhibition and 12 mg GAE/g (dry weight) for antioxidant activity and phenolic compounds, respectively. These values are similar or even higher than those reported in literature using specific parts of fruits and vegetables.

Efficient production of a polyhydroxyalkanoate by Azotobacter vinelandii OP using apple residues as promising feedstock.

Fruit residues are attractive substrates for the production of bacterial polyhydroxyalkanoates due to the high contents of fermentable sugars and the fast, simple, and efficient pretreatment methods required. In this study, apple residues, mainly apple peel, were used as the sole carbon source in cultures of the bacterium Azotobacter vinelandii OP to produce poly-3-hydroxybutyrate (P3HB). Conversion from the residue to total sugars was highly effective, achieving conversions of up to 65.4 % w w-1 when using 1 % v v-1 sulfuric acid and 58.3 % w w-1 in the absence of acid (only water). The cultures were evaluated at the shake-flask scale and in 3-L bioreactors using a defined medium under nitrogen starvation conditions. The results showed the production of up to 3.94 g L-1 P3HB in a bioreactor, reaching an accumulation of 67.3 % w w-1 when using apple residues. For the PHB obtained from the cultures with apple residues, a melting point of 179.99 °C and a maximum degradation temperature of 274.64 °C were calculated. A P3HB production strategy is shown using easily hydrolysable fruit residues to achieve production yields comparable to those obtained with pure sugars under similar cultivation conditions.

Extracts from jatobá (Hymenaea courbaril L.) peel and seeds: Antioxidant and antimicrobial activities and synergistic effect of extract combinations.

In this work, the in vitro antioxidant and antimicrobial potential of hydroalcoholic extracts from the peel and seeds of jatobá fruit and the synergistic effect of their combination against pathogenic bacteria were evaluated. The 80% ethanol fruit seed extract showed a greater antioxidant potential and higher total phenolic content (5135.61 mg GAE 100 g dry residue-1) than the maximum value obtained from peel extract using 50% ethanol (2614.74 1 mg GAE 100 g dry residue-1). Moreover, 70% and 80% ethanol seed extracts inhibited most bacteria, especially Pseudomonas aeruginosa, with the lowest values of minimum inhibitory concentration (1.0 and 8.0 mg mL-1), when compared with extracts from peel. Combining the 70% ethanol extracts from peels and seeds reduced their inhibitory concentration by about 4 to 32 times against Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, P. aeruginosa and Salmonella enteritidis, when compared to each extract alone. Extracts from the peel and seeds of the jatobá fruit showed potential as natural antioxidants and antimicrobials.

Extraction and Characterization of Antioxidant Peptides from Fruit Residues.

Fruit residues with high protein contents are generated during the processing of some fruits. These sustainable sources of proteins are usually discarded and, in all cases, underused. In addition to proteins, these residues can also be sources of peptides with protective effects against oxidative damage. The revalorization of these residues, as sources of antioxidant peptides, requires the development of suitable methodologies for their extraction and the application of analytical techniques for their characterization. The exploitation of these residues involves two main steps: the extraction and purification of proteins and their hydrolysis to release peptides. The extraction of proteins is mainly carried out under alkaline conditions and, in some cases, denaturing reagents are also employed to improve protein solubilization. Alternatively, more sustainable strategies based on the use of high-intensity focused ultrasounds, microwaves, pressurized liquids, electric fields, or discharges, as well as deep eutectic solvents, are being implemented for the extraction of proteins. The scarce selectivity of these extraction methods usually makes the subsequent purification of proteins necessary. The purification of proteins based on their precipitation or the use of ultrafiltration has been the usual procedure, but new strategies based on nanomaterials are also being explored. The release of potential antioxidant peptides from proteins is the next step. Microbial fermentation and, especially, digestion with enzymes such as Alcalase, thermolysin, or flavourzyme have been the most common. Released peptides are next characterized by the evaluation of their antioxidant properties and the application of proteomic tools to identify their sequences.

In vitro gastrointestinal digestion and probiotics fermentation impact on bioaccessbility of phenolics compounds and antioxidant capacity of some native and exotic fruit residues with potential antidiabetic effects.

A bioaccessibility study on polyphenols, flavonoids and antioxidant capacity after the in vitro simulated digestion was evaluated for extract of fruit (caja-umbu, cashew apple, canafistula, cupuassu, soursop, manguba and strawberry) residues. The results show that ORAC assay presented a significant increase (p ≤ 0.05) in bioaccessibility varying from 35.99 ± 0.02% (caja-umbu residue) to 339.83 ± 0.06% (cupuassu residue) after the digestion process. Approximately 15.01 ± 1.54 to 237.77 ± 4.10% of phenolic compounds were bioaccessible after probiotics fermentation. The identification and quantification of phenolic compounds were performed through the UHPLC-QDa-MS system. Catechin and epicatechin were widely detected in all fruit residues. After the gastrointestinal digestion and probiotics fermentation the contents of simple phenolics and hydroxybenzoic acids increased. Also, the α-amylase inhibitory activity exhibited a maximum value of 98.66 ± 1.41% for soursop residue. To the best of our knowledge, for the first time, bioaccessibility study on caja-umbu, canafistula and manguba residues was performed in association with antidiabetic effects. The soursop residue presented the highest bioaccessibility and can be potentially explored for application in functional foods and pharmaceuticals. Therefore, the joint consumption of probiotics and phytochemicals are essential for the effective assimilation by the human organism.

Evaluation of bioactive compounds potential and antioxidant activity in some Brazilian exotic fruit residues.

The agroindustrial residues have been recognized as important sources of some prominent chemical compounds and hence a viable strategy of obtaining bioactive compounds could be applied to them. The present study was aimed to investigate the presence of bioactive compounds and the antioxidant activity of some Brazilian exotic fruits (achachairu, araçá-boi, bacaba) residues. The antioxidant capacity of fruit residues was evaluated by ORAC, FRAP and ABTS assays. The contents of total phenolic compounds, flavonoids, chlorophylls and carotenoids were determined. The identification and quantification of the phenolic compounds were performed by using the UHPLC-QqQ-MS/MS system. The compounds cinnamic acid, p-coumaric acid, epicatechin and quercetin were identified and quantified in all fruits residues. The residue with the highest antioxidant capacity was bacaba for ORAC (15,285.51±20.38µmolTE/100g) and FRAP (16,916.37±10.01µmolTE/100g) assays, as well as total phenolic compounds in its methanolic extract (1537.45±73.35mgGAE/100g).

Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion.

Huge amounts of fruit residues are produced and abandoned annually. The high moisture and organic contents of these residues makes them a big problem to the environment. Conversely, they are a potential resource to the world. Anaerobic digestion is a good way to utilize these organic wastes. In this study, the biomethane conversion performances of a large number of fruit residues were determined and compared using batch anaerobic digestion, a reliable and easily accessible method. The results showed that some fruit residues containing high contents of lipids and carbohydrates, such as loquat peels and rambutan seeds, were well fit for anaerobic digestion. Contrarily, residues with high lignin content were strongly recommended not to be used as a single substrate for methane production. Multiple linear regression model was adopted to simulate the correlation between the organic component of these fruit residues and their experimental methane yield, through which the experimental methane yield could probably be predicted for any other fruit residues. Four kinetic models were used to predict the batch anaerobic digestion process of different fruit residues. It was shown that the modified Gompertz and Cone models were better fit for the fruit residues compared to the first-order and Fitzhugh models. The first findings of this study could provide useful reference and guidance for future studies regarding the applications and potential utilization of fruit residues.

In-vitro cancer cell cytotoxicity and alpha amylase inhibition effect of seven tropical fruit residues

Objective:To determine quantitative phytochemical, anticancer and antidiabetic effect of seven Indian tropical fruit residues. Methods:In-vitro cytotoxic activity (IC50) was evaluated against cervical cancer cells (HeLa), breast cancer cells (MCF-7), hepatocellular carcinoma cells (HepG-2) and bone sarcoma cells (MG-63) and alpha amylase inhibition assay was used for antidiabetic activity. Results: Results of phytochemical analysis revealed that all residues contained remarkable amount of alkaloid, saponin, tannin and flavonoid. Notable cancer cell growth inhibition was observed for the extract from Carissa carandas pomace and Litchi sinensis seeds with IC50 values ranged from 56.72 to 89.24 μg/mL. Alpha amylase inhibition assay was measured at six different concentrations (5, 10, 25, 50, 100 and 200 mg/mL) by using different solvent extract. Results showed that Carissa carandas possessed best activity with IC50 value as 29.66 mg/mL followed by other residues in methanol extract. Conclusions:Study suggests that these fruit residues demonstrate promising antidiabetic and anticancer activity that substantiated its ethno medicinal use and may provide new molecules for the treatment of these diseases.

Desarrollo y evlluación de un postre lácteo con fibra de naranja / Preparation andeevaluation of a milk dessert with orange fiber

El consumo de fibra dietaria se ha asociado con propiedades de alimentos funcionales porque provee condiciones que favorecen la salud intestinal, la prevención de cáncer de colon, las enfermedades cardiovasculares y ayuda en el mantenimiento del peso. En el presente estudio se busca elaborar y evaluar un postre lácteo adicionado con fibra de residuos resultantes de la separación de pulpa de naranja. Se selecciona la fibra de naranja como materia prima para la elaboración de postres, ya que se trata de una buena fuente de fibra dietaria tanto soluble como insoluble; además, en la caracterización sensorial, realizada por jueces entrenados, se encuentra que esta fibra presenta olor y aroma propios de la fruta y características texturales bucales agradables. El análisis proximal muestra que la fibra de naranja contiene un 59.1 % de fibra dietaria total FDT y la fracción soluble FDS es de 27.5 %, con buen contenido de hierro y fósforo y otros nutrientes a excepción de la grasa cruda. Desde el punto de vista tecnológico es factible incorporar hasta un 5.0 % de fibra de naranja en el postre lácteo, el cual presenta un 2.1 % de grasa láctea, 7.3 de sólidos lácteos y un 25.3 % de sólidos totales. El perfil del sabor muestra que el postre con fibra de naranja presenta una calidad sensorial media. Los descriptores de sabor que presenta este producto son: naranja, cítrico, ácido, dulce, cocido y con un sabor residual amargo. Los descriptores de textura percibidos son: húmedo, blando, masticable y fibroso. Este nuevo producto alimenticio aporta los nutrientes propios y una cantidad adicional de fibra, lo que lo convierte en alimento saludable y una alternativa agradable, sencilla y económica para que las personas incrementen el consumo diario de fibra dietaria. Además, mediante el aprovechamiento de los residuos de la transformación de naranja se contribuye a disminuir la contaminación ambiental.

The consumption of dietary fiber has been associated with functional food properties which improves people's intestinal health. It also contributes towards the prevention of colon cancer, cardiovascular diseases, and weight control. The purpose of this study is to prepare and evaluate a milk dessert added with fiber from residues resulting from orange pulp separation. Orange fiber is selected as a raw material to prepare desserts because orange is a good source of soluble and insoluble dietary fiber and besides in the sensorial characterization made by trained judges, it was found that this fiber has odor and aroma of the fruit -the orange- and pleasant textural mouth characteristics. Proximal analysis shows that orange fiber has 59.1 % of total dietary fiber, and the soluble fraction is 27.5 %, with a good content of iron, phosphorus, and other nutrients, except for raw grease. From the technological point of view, it is feasible to incorporate until 5.0 % of orange fiber in the milk dessert, which presents 2.1 % of milk fat, 7.3 of milk solids, and a 25.3 % of total solids. The taste profile shows that the dessert with orange fiber has a medium sensorial quality. Taste describers of this product are: orange, citric, sour, sweet, cooked, and with a residual bitter flavor. Texture describers perceived are: humid, soft, masticable, and fibrous. This new food contributes with its own nutrients and with an additional quantity of fibers which make it a healthy food and are a pleasant, simple, and economic alternative, so people can increase their daily intake of dietary fiber. Besides, through the use of residues in orange transformation, environmental pollution can be decreased.