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•Walnut shell (WS) and pea pod (PP) are underutilized sources of xylan.•Xylan is present as low branched 4-O-methyl-glucuronoxylan and/or arabinoglucuronoxylan.•Delignificatinon had a ...major effect on xylan extractability from WS and PP.•Hydrolysis by GH11 endo-xylanase generated mostly xylose, xylobiose and xylotriose.•Xylan conversion and XOS profile varied with enzyme concentration and hydrolysis time.
According to the high interest in agro-industrial waste reutilisation, underutilised lignocellulosic materials, such as walnut shell (WS) and pea pod (PP), come in focus. The aim of this paper was to evaluate WS and PP as sources for the production of xylooligosaccharides (XOS). Hemicelluloses from WS and PP were recovered by combining varying parameters of delignification and alkaline extraction. At optimal recovery conditions, the fractions were further hydrolysed to XOS using GH11 endo-xylanase, by varying time and enzyme concentration. Xylose was predominant in the monomeric composition of the obtained hemicelluloses, building low-branched (arabino)glucuronoxylan, in WS exclusively, while in PP some xyloglucan as well. Delignification was essential for high recovery of total xylose from the materials, up to at least 70 %. High xylan conversions were obtained for 24 h hydrolysis, resulting in xylobiose and xylotriose when using low enzyme concentration, while in xylose and xylobiose with high enzyme concentration.
A combined treatment based on high-pressure carbon dioxide and high-power ultrasound (HPCD + HPU) technologies was investigated for the pasteurization of fresh-cut coconut. Inactivation kinetics of ...both the natural microbiota and Salmonella enterica typhimurium spiked on the product were determined at 12 MPa and 10 W, delivered every 2 min of treatment, as a function of temperature (from 24 to 50 °C) and treatment time (from 5 up to 30 min). Additionally, to study the effect of HPCD + HPU on the quality of the product, physicochemical attributes (total acidity, pH, color, texture, dry matter, fat content, enzymatic activity, antioxidant capacity, phenols, flavonoids, and phenolic acids) were measured after the combined treatment and during a refrigerated shelf life of 4 weeks. The results revealed that HPCD + HPU increased microbial inactivation rates compared with HPCD alone: 8 log reductions of S. typhimurium were achieved with HPCD + HPU at 12 MPa, 40 °C, 20 min, while just a 4 log reduction was achieved with HPCD alone. Similar results were obtained for the natural microbiota; milder conditions of temperature and pressure were sufficient to assure inactivation to undetectable levels even of mesophilic microorganisms, the most resistant ones. Total acidity and pH did not change after the combined treatment and during the entire storage of 4 weeks, while slight differences were observed for the other physicochemical parameters. Overall, the results showed the feasibility and the potential of HPCD + HPU as an innovative non-thermal technology for the pasteurization of fresh-cut fruits.
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► HPCD partially inactivated the natural microbial flora and enzymes in fresh-cut carrot. ► Bioactive compounds and antioxidant capacity of the samples were preserved. ► 90% texture ...reduction was observed for the samples treated at 12MPa, 40°C, 15min. ► HPCD did not seem to be feasible as innovative technique to pasteurize fresh-cut carrot.
High pressure carbon dioxide treatment (HPCD) was applied for the pasteurization of fresh-cut carrot. The inactivation kinetics of the natural microbial flora were determined as a function of the treatment conditions (8 or 12MPa, 22, 35, 40, 45°C, 5–45min) to investigate the more feasible process conditions to assure a microbial stability to the product. Further, the effect of HPCD treatment on the qualitative aspects of the product in terms of enzymatic activity (polyphenol oxidase (PPO), peroxidase (POD), pectin methylesterase (PME) and polygalacturonase (PG)), bioactive composition (phenol, flavonoid, carotenoid, ascorbic acid content and antioxidant capacity), texture, pH and tritatable acidity (TA) were measured. A storage study at refrigerated conditions (4°C) for 4 weeks was also performed to monitor the microbial and qualitative stability of the product. The results showed that 12MPa, 40°C, 15min were effective to inactivate the natural microbial flora and assure the microbial and enzymatic stability of the product for 4 weeks. Bioactive compounds content, antioxidant capacity, and enzyme stability were all preserved with the exception of the texture which exhibited a significant reduction up to 90% compared to the control, and the ascorbic acid content which was reduced down to 40%.
Since most studies regarding immortelle (Helichrysum italicum) are focused on the properties and composition of its essential oil, the aim of this study was to develop edible films based on ...immortelle water extract. Alginate and pectin combined with various proteins served as carriers for the formulation of biodegradable films and hydrogel particles. Films with different biopolymers and incorporated hydrogel particles were prepared by casting method and hydrogel particles were produced by ionic gelation. The bioactive profile (the content of total (TPC) and specific polyphenols, hydroxycinnamic acids (HCAC) and antioxidant capacity (AC)) of the developed matrices was characterized using spectrophotometric methods and high performance liquid chromatography (HPLC). Zeta-potential and rheological properties of alginate- and pectin-based film-forming solutions and physico-chemical (color, particle size, film thickness, dry matter content) and sensory properties of the developed particles and films were evaluated. The highest TPC (31.31 mg GAE/g sample) and HCAC (27.20 mg CAE/g sample) as well as the highest AC (0.15 mmol TE/g sample) was determined in pectin-based films. The addition of proteins decreased the content of the examined bioactive parameters, while the addition of hydrogel particles altered their physico-chemical properties. The obtained results indicate a great application potential of the developed biodegradable matrices.
•Immortelle extract is abundant in polyphenols, resulting in high bioactivity.•Chlorogenic acid derivatives dominate the bioactive profile of immortelle films.•The addition of hydrogels significantly enriched the bioactive profile of the films.•Polyphenols entrapped in films with hydrogels exhibit a prolonged release in SGF.•Alginate-based films have more desirable sensory properties than the pectin-ones.
Summary
The aim of this study was to develop functional edible films containing cocoa (Theobroma cacao L.) powder extract using alginate, pectin and chitosan in combination with proteins (whey ...protein isolate, soya and hemp protein). The films were examined for their physico‐chemical (dry matter content, colour, thickness), mechanical (elongation at break (EAB)), bioactive (the content of total polyphenols (TPC), flavan‐3‐ols (F3olC), antioxidant capacity (AC)) and sensory properties. The plain alginate film exhibited the highest EAB (29.1%). The highest TPC and F3olC were determined in plain alginate (29 mg GAE/g and 2.75 mg (+)‐catechin/g) and pectin (29 mg GAE/g and 2.25 mg (+)‐catechin/g) films. The addition of proteins resulted in prolonged release of polyphenols and enhanced functional properties; however, the formation of protein–polyphenol complexes caused slight alterations in the bioactive composition of the films. The obtained results indicate a high potential of the developed films as functional, biodegradable form of active food packaging.
At optimised formulations of developed edible films obtained by combining cocoa powder extract, polysaccharide and protein isolate, the films exhibited prolonged release of bioactive compounds as well as desirable mechanical and sensory properties which accents their potential usability as alternative packaging.
The impact of supercritical CO2 (SC-CO2) process on the quality attributes of fresh-cut coconut has been investigated to establish the acceptability of SC-CO2 treated products by the consumers. Two ...process conditions, previously identified as optimal to reduce the microbial content of the product, were studied: 12 MPa, 40°C, 30 min and 12 MPa, 45°C, 15 min. The results highlighted that both conditions induced some effects on product attributes. After 30 min of treatment at 12 MPa and 40°C a decrease of lightness (8%), pH (13%), fat content (24%), total phenol content (29%), flavonoid compounds (49%), antioxidant capacity (30%) and an increase of dry matter (11%) and titratable acidity (51.1%) were observed while polyphenol oxidase (PPO) exhibited 35% and 98.5% inactivation. Peroxidase enzyme activity increased by 77.8% and 30.4% at 12 MPa, 40°C, 30 min and 12 MPa, 45°C, 15 min, respectively. Sensory evaluations revealed no significant differences in appearance, texture, taste, and aroma of treated fresh-cut coconut compared to the untreated. The study confirms the feasibility of SC-CO2 process for the pasteurization of fresh fruits with a firm structure and opens the door to the possibility of exploiting such a technology at industrial level.
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