Physicochemical and In Vitro Starch Residual Digestion Structures of Extruded Maize and Sorghum Starches Added with Sodium Stearoyl Lactylate.

This research aimed to characterize the physicochemical, in vitro digestion, and structural features of digestion residues of maize and sorghum starches subjected to thermoplastic extrusion, along with the influence of Sodium Stearoyl Lactylate (SSL), to obtain improved starches for food applications and to understand their behavior when consumed as a food ingredient. The morphology of the extruded materials showed remanent starch granules when SSL was used. A higher amount of medium and large linear glucan chains were found in these particles, influencing higher thermal stability (ΔH ≈ 4 J/g) and a residual crystallinity arrangement varying from 7 to 17% in the extrudates. Such structural features were correlated with their digestibility, where slowly digestible starch (SDS) and resistant starch (RS) fractions ranged widely (from 18.28 to 27.88% and from 0.13 to 21.41%, respectively). By analyzing the data with a Principal component analysis (PCA), we found strong influences of B2 and B3 type chains on the thermal stability of the extrudates. The amylose and smaller glucan chains (A and B1) also significantly affected the emulsifying and foam stability properties. This research contributes to the molecular knowledge of starch in extruded products with broad food applications.

Arabinoxylans Release from Brewers' Spent Grain Using Extrusion and Solid-State Fermentation with Fusarium oxysporum and the Antioxidant Capacity of the Extracts.

Brewers' spent grain (BSG) is the most abundant byproduct generated from the beer-brewing process. BSG is a material rich in hemicellulose, composed of arabinoxylans (AX). However, the high crosslinking of this material causes low availability of AX, for which it is necessary to apply different treatments. The objective of this research is to increase the release of arabinoxylans through solid-state fermentation with Fusarium oxysporum f. sp. lycopersici using extruded brewery spent grain. First, the BSG is subjected to two types of physical treatments: extrusion at 20% moisture, 200 rpm and 50 °C (BSGe), and blade milling (BSGm). The chemical composition is determined for each sample (BSG, BSGe and BSGm). Subsequently, the solid-state fermentation process (SSF) is carried out on each sample. The fermentation kinetics at 30 °C are monitored for 7 days. Once the SSF concludes, AX are extracted, and the purity of AX is determined by the phloroglucinol colorimetric assay. Finally, the total phenolic compounds, phenolic acids and antioxidant capacity by DPPH are quantified. No significant differences (p ≥ 0.05) in the protein, lipid, ash or total dietary fiber contents are found among the samples. No significant difference (p ≥ 0.05) in the content of soluble fiber is found, although BSGe and BSGm have higher values than BSG. On the other hand, the yields of soluble AX exhibit significant differences (p ≤ 0.05) among nonfermented samples (BSG, 0.03%; BSGm, 0.53%; BSGe, 0.70%) and with SSF (BSG, 2.95%; BSGm, 6.24%; and BSGe, 9.58%). In addition, the contents of free phenolic compounds and free phenolic acids and the percent inhibition of free extracts by 2,2-diphenyl-1-picrylhydrazyl (DPPH) differ significantly (p ≤ 0.05) between samples subjected to SSF and nonfermented samples. Therefore, extrusion and SSF treatment increase AX release from BSG as well as the antioxidant capacity of the extracts.

Comparison of Regular and Selenium-Enriched Tortillas Produced from Sprouted Corn Kernels.

Corn kernels were soaked with different selenium (Se) solutions (0, 12 or 24 mg Na2SeO3/L), sprouted for different times and then lime-cooked for the pilot plant production of tortillas. The dough and tortillas were quantified in terms of total Se, starch and protein content. Also, in vitro digestibility, texture, color, and sensory properties were evaluated. Results indicated that lime-cooking times were significantly reduced from 39.15 to 14.34, 8.42 and 2.80 min when whole corn was compared with kernels germinated for 1, 2 or 3 days. The Se content of regular tortillas (0.08 µg/g dw) increased about eight-fold in tortillas (0.651-0.625 µg/g dw) produced of corn germinated for two day and treated with 24 mg of Na2SeO3/L. The highest α-amylase activity and lower starch viscosity values were observed in 3-day germinated supplemented with the highest Se. Se-enriched tortillas produced from 2-day sprouted kernels treated with 12 mg Na2SeO3 showed the highest levels of general acceptability, texture and flavor.

Germinated chickpea-maize extrudates with high protein content and reduced starch digestibility.

The objective of this study was to produce maize extrudates supplemented with germinated chickpea flour to increase the contents of resistant starch (RS) and protein. Six extrudates were formulated using maize grits (ME), germinated chickpea flour (GCE) and different blends of maize and 10%, 20%, 30%, or 40% of germinated chickpea flour (MGCE-10, MGCE-20, MGCE-30, or MGCE-40). Increase of RS was observed in the defatted samples due to germinated chickpea flour addition. In the nondefatted samples, the highest content of RS was observed in GCE followed by ME and the different MGCE. Interaction between fat, starch, and protein by improved intramolecular association was assessed by Fourier transform- infrared spectroscopy (FTIR). Amylose-lipid complexes in nondefatted samples increased the content of RS in comparison to defatted samples. The highest expansion index was obtained in MGCE-30 and MGCE-40. ME had the highest hardness and crispiness. Germinated chickpea flour increased the water absorption index (WAI), but reduced water solubility index (WSI) when it was combined with maize grits to produce extrudates. The in vitro protein digestibility (IVPD) was higher in the GCE and MGCE with more than 20% of germinated chickpea flour compared to ME. MGCE-20 and MGCE-30 showed the highest acceptability of the supplemented extrudates with 50% more protein than ME, a similar IVPD to that of GCE, and good functional characteristics. PRACTICAL APPLICATION: Combining maize and germinated chickpea flour is a good strategy to have a controlled digestibility of starch and increase the plant based protein content in healthier snacks.

Aqueous Two-Phase Systems for Cleanup and Recovery of Enzymes from Plants and Plant-Derived Extracts.

The increasing interest of the biopharmaceutical industry to exploit plants as a commercially viable production system is demanding the development of new strategies to maximize product recovery. Aqueous two-phase systems (ATPSs) are a primary recovery technique that has shown great potential for the efficient extraction and purification of biological products, from organelles to proteins and low-molecular-weight compounds. The evaluation of different system parameters upon the partitioning behavior can provide the conditions that favor the concentration of contaminants and the desired target protein in opposite phases. The protocols described here provide the basic strategy to explore the use of ATPSs for the isolation and partial purification of native and recombinant proteins from plants and plant-derived extracts.

Sequential application of postharvest wounding stress and extrusion as an innovative tool to increase the concentration of free and bound phenolics in carrots.

Postharvest wounding stress in carrots induces the accumulation of phenolics, whereas extrusion generates modifications in the nutritional profiles of food matrixes. In the present study, the sequential application of wounding stress and extrusion on total free and bound phenolics as well as on carotenoid profiles of carrots was evaluated. Wounding was applied by shredding carrots and storing the tissue (48 h, 15 °C). The stressed-tissue was dehydrated and extruded at 63 °C or 109 °C and at continuous or expansion screw configurations. Extrudates were milled and sieved before phytochemical analysis. Wounding increased total free (288.1%) and bound (407.6%) phenolic content, whereas the carotenoid content was unaltered. The free and bound phenolics that showed the highest increase due to wounding were the chlorogenic (579.8%) and p-coumaric (390.9%) acids. Extrusion, at 109 °C under expansion screw configuration, further increased the wound-induced accumulation of total free (296.6%) and bound (22.1%) phenolics and induced trans-cis isomerization of ß-carotene.

Whole unripe plantain (Musa paradisiaca L.) as raw material for bioethanol production.

BACKGROUND: The use of byproducts such as rejected plantain with final disposition problems and conversion processes with 'green' technologies are important research topics. Bioethanol production from crops with a high content of fermentable sugars is an alternative to that from traditional crops (corn and sugar cane). The aim of this work was to study the use of whole (peel and pulp) unripe plantain (WP) for bioethanol production. RESULTS: Lab-scale liquefaction and saccharification of both materials released mainly three carbohydrates, glucose (9.02 mg g-1 ), maltose (0.45 mg g-1 ) and xylose (0.25 mg g-1 ). The WP saccharification required the use of pectinase and cellulase because of the high amounts of pectin and cellulose associated with the peel. Fermentation for 11 h produced similar ethanol concentration for both samples, but at the end of fermentation (32 h), the ethanol production was higher in the WP (58.6 mL L-1 ) compared with the plantain pulp (PP) (45.5 mL L-1 ). The theoretical ethanol yield was lower with WP (67%) than with PP (90%). CONCLUSION: WP can be an alternative raw material for bioethanol production. © 2019 Society of Chemical Industry.

In Vitro Antioxidant Activity Optimization of Nut Shell (Carya illinoinensis) by Extrusion Using Response Surface Methods.

The pecan (Carya illinoinensis) nut shell is an important byproduct of the food processing industry that has not been previously explored as an antioxidant compound. This work aims to study the effect of the extrusion temperature and screw speed on the moisture content, water and oil absorption index, water solubility index, color, phenolic compounds, condensed tannin compounds, and antioxidant activity of pecan nut shell extrudates. Extrusion variables were adjusted using a response surface methodology. Extrusion, performed at 70 °C and 150 rpm, almost doubled the concentration of polyphenols in the non-extruded shell and significantly increased radical scavenging activity. Compounds in extrudates, performed at 70 °C and 150 rpm, were quantified by high-performance liquid chromatography (HPLC) with a diode-array detector (DAD) and identified by liquid chromatography coupled with time-of-flight mass spectrometry (LC-MSD-TOF). Extrusion significantly increased most phenolic acid compounds, including gallic acid, ellagic acid pentose, ellagic acid, dimethyl ellagic acid rhamnoside, and dimethyl ellagic acid. The soluble fiber in extrudates was more than three-fold higher than in the control. Therefore, extrusion at 70 °C and 150 rpm increased the concentration of phenolic compounds, antioxidant activity, and total dietary and soluble fiber. Our findings support the notion that extruded pecan nut shell can be used in clean-label products and improve their nutraceutical value.

Rheology, acceptability and texture of wheat flour tortillas supplemented with soybean residue.

Dry soybean (Glycine max) residue (SBR) is a byproduct rich in dietary fibre and protein with high levels of essential amino acids. The effects due to the substitution of refined wheat flour with 5% or 10% SBR in dough rheology and hot-press tortilla texture, dimensions, colour, protein and dietary fibre contents were studied. Substitution of 10% SBR improved flour in terms of gluten strength and sedimentation without significantly affecting dough hardness, cohesiveness, adhesiveness, and extensibility. The dimensions, colour and sensory acceptance of the supplemented tortillas were not affected by the addition of the SBR. The 10% SBR tortillas contained 1.77 times more insoluble dietary fibre, protein content of 9.3%, in vitro protein digestibility of 84% and protein digestibility corrected amino acid score (PDCAAS) of 52.63%. Results indicated that wheat flour tortillas with 10% SBR an excellent alternative to regular counterparts owing to their higher dietary fibre and protein quantity and quality.

Effects of extrusion pretreatment parameters on sweet sorghum bagasse enzymatic hydrolysis and its subsequent conversion into bioethanol.

Second-generation bioethanol production from sweet sorghum bagasse first extruded at different conditions and then treated with cell wall degrading enzymes and fermented with I. orientalis was determined. The twin extruder parameters tested were barrel temperature, screws speed, and feedstock moisture content using surface response methodology. The best extrusion conditions were 100°C, 200 rpm, and 30% conditioning moisture content. This nonchemical and continuous pretreatment did not generate inhibitory compounds. The extruded feedstocks were saccharified varying the biocatalysis time and solids loading. The best conditions were 20% solids loading and 72 h of enzymatic treatment. These particular conditions converted 70% of the total fibrous carbohydrates into total fermentable C5 and C6 sugars. The extruded enzymatically hydrolyzed sweet sorghum bagasse was fermented with the strain I. orientalis at 12% solids obtaining a yield of 198.1 mL of ethanol per kilogram of bagasse (dw).

Production of ethanol from sweet sorghum bagasse pretreated with different chemical and physical processes and saccharified with fiber degrading enzymes.

The C5 and C6 sugars generated from sweet sorghum bagasse pretreated with five different chemical or physical schemes and then further hydrolyzed with a fibrolytic cocktail were determined. Hydrolysates were fermented with three yeast strains in order to determine which combination generated the highest amount of bioethanol. The bagasse only treated with the enzyme complex generated 50% of the total C5 and C6 sugars available. The pressure-cooked and extruded pretreatments further hydrolyzed with the enzymes generated 17% more sugars compared to the enzyme alone treatment. The enzyme increased the total sugar content in approximately 40% in the three acid pretreated hydrolysates. Among the different pretreatments, only the extrusion process did not generate inhibitors acetic acid, furfural and 5-hydroxymethylfurfural. At 24 h fermentation, the strains Saccharomyces cerevisiae and Issatchenkia orientalis produced, respectively 183.9 and 209.2 mg ethanol/g dry bagasse previously treated with HCl and enzymes.

Effects of different acid hydrolyses on the conversion of sweet sorghum bagasse into C5 and C6 sugars and yeast inhibitors using response surface methodology.

Two different diluted acid pretreatments (sulfuric and hydrochloric acid) and one mixture of these acids were tested in sweet sorghum bagasse and analyzed through surface response methodologies. The response variables were C5 and C6 sugars and inhibitors (acetic acid, 5-hydroxymethylfurfural, and furfural). Results indicated that the three different pretreatments yielded similar amounts of total potentially fermentable sugars. The proposed acid hydrolysis schemes liberated 56-57% of total sugars available in the sweet sorghum bagasse (390-415 mg sugar/g bagasse) and 44-61 mg total inhibitors/g bagasse. A mild detoxification was effectively used in the optimized hydrolysates, but did not have effect an effect in the HCl/H(2)SO(4) mixture. The acetic acid and HMF significantly decreased in the HCl and H(2)SO(4) detoxified hydrolysates without any significant degradation of sugars. The HCl treatment was a good alternative due to its relatively lower hydrolysis time and adequate generation of C5 and C6 fermentable sugars.