65 research outputs found
Effects of polysaccharide-based edible coatings enriched with dietary fiber on quality attributes of fresh-cut apples
Little information is available regarding the incorporation of dietary fiber into edible films and coatings. In this work, apple fiber and inulin were incorporated into polysaccharide-based (alginate, pectine and gellan gum) edible coating formulations and their effects on the quality attributes of fresh-cut apples were evaluated. Antioxidant properties, color, firmness, sensory quality and microbial growth of fresh-cut apple were studied during 16 days of storage at 4 A degrees C. Results show that dietary fiber extracts incorporated to gellan gum, pectin and alginate-based coatings together with calcium chloride and ascorbic acid successfully maintained the firmness and color of coated fresh-cut apples in comparison with uncoated control samples, which presented severe texture softening and browning. The firmness of apple pieces coated with polysaccharide-based coating formulations incorporating apple fiber doubled, and sometimes tripled, that of uncoated samples. Any of the assayed coatings exhibited a positive effect on the sensory properties of fresh-cut apples. The incorporation of apple fiber, together with the use of ascorbic acid, contributed to keep the antioxidant potential of the fruit at least during the first week of storage. Furthermore, gellan gum coatings had a marked effect in reducing mesophilic and psychrophilic counts on fresh-cut apples throughout storage regardless the addition of dietary fibers. The results achieved demonstrate the feasibility of the addition of dietary fiber to edible coating formulations for increasing the nutritional value of fresh-cut apples without compromising their fresh-like quality attributes.This work was supported by Agencia Nacional de PromociĂłn CientĂfica y TecnolĂłgica (ANPCyT, Argentina) and by Spanish Ministry of Economy and Competitiveness, through the project AGL2010-21572. An ICREA Academia Award is also acknowledged
Pomegranate (Punica granatum L.) Peel Extracts as Antimicrobial and Antioxidant Additives Used in Alfalfa Sprouts
Aqueous and ethanolic pomegranate peel extracts (PPE) were studied as a source of
phenolic compounds with antimicrobial, anti-quorum sensing, and antioxidant properties. The
aqueous extract showed higher total phenolic and flavonoid content (153.43 mg GAE/g and 45.74,
respectively) and antioxidant capacity (DPPH radical inhibition: 86.12%, ABTS radical scavenging
capacity: 958.21 mg TE/dw) compared to the ethanolic extract. The main phenolic compounds
identified by UPLC-DAD were chlorogenic and gallic acids. The aqueous PPE extract showed
antimicrobial activity against Listeria monocytogenes, Salmonella Typhimurium, Candida tropicalis (MICs
19â30 mg/mL), and anti-quorum sensing activity expressed as inhibition of Chromobacterium violaceum
violacein production (%). The aqueous PPE extracts at 25 mg/mL applied on alfalfa sprouts reduced
psychrophilic bacteria (1.12 Log CFU/100 g) and total coliforms (1.23 Log CFU/100 g) and increased
the antioxidant capacity of the treated sprouts (55.13 mol TE/100 g (DPPH) and 126.56 mol
TE/100 g (ABTS)) compared to untreated alfalfa. This study emphasizes PPEâs antioxidant and
antimicrobial activities in alfalfa sprouts preservation
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Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life
Lettuce discolouration is a key post-harvest trait. The major enzyme controlling oxidative discolouration
has long been considered to be polyphenol oxidase (PPO) however, levels of PPO and subsequent development of discolouration symptoms have not always correlated. The predominance of a latent state of the enzyme in plant tissues combined with substrate activation and contemporaneous suicide inactivation
mechanisms are considered as potential explanations for
this phenomenon. Leaf tissue physical properties have
been associated with subsequent discolouration and
these may be influenced by variation in nutrient
availability, especially excess nitrogen and head maturity at harvest. Mild calcium and irrigation stress has
also been associated with a reduction in subsequent
discolouration, although excess irrigation has been
linked to increased discolouration potentially through
leaf physical properties. These environmental factors,
including high temperature and UV light intensities,
often have impacts on levels of phenolic compounds
linking the environmental responses to the biochemistry
of the PPO pathway. Breeding strategies targeting the
PALand PPOpathway biochemistry and environmental
response genes are discussed as a more cost-effective
method of mitigating oxidative discolouration then
either modified atmosphere packaging or post-harvest
treatments, although current understanding of the
biochemistry means that such programs are likely to
be limited in nature and it is likely that they will need to be deployed alongside other methods for the foreseeable future
Preservation of fresh-cut apple quality attributes by pulsed light in combination with gellan gum-based prebiotic edible coatings
Pulsed light (PL) has received considerable attention during the last years as a non-thermal method for the superficial decontamination of fresh foods. The aim of the present study was to evaluate the quality attributes of fresh-cut 'Golden Delicious' apples as affected by the combined application of a pulsed light treatment (12 j/cm(2)) and a gellan-gum based (0.5% w/v) edible coating enriched with apple fiber. Changes in color, firmness, antioxidant capacity, microbial growth and sensory attributes were determined during 14 days of storage at 4 degrees C. The combined application of coating and PL treatment retarded the microbiological deterioration of fresh-cut apples and maintained the sensory attribute scores above the rejection limits after prolonged storage. Incorporation of fiber in the coating formulation did not curb the sensory acceptability of apple cubes. Results show that the use of a gellan-gum based coating incorporating apple fiber followed by the application of a PL treatment significantly reduced softening and browning of apple pieces through storage. Our results reveal that PL treatments applied to gellan-coated fresh-cut apples can be used to decontaminate the cut fruit surface without dramatically affecting its fresh-like quality attributes, thus conferring prebiotic potential and contributing to their shelf-life extensio
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