The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature ...and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 107 CFU mL−1 as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products.
•Bacillus amyloliquefaciens BUZ-14 inhibited major postharvest rots in fruits.•Preventive treatments were effective against Penicillium spp. in oranges and apples.•B. amyloliquefaciens exhibited a curative effect against brown rot in stone fruits.•BUZ-14 survived at cool temperatures making it suitable for postharvest treatment.
The effects of ascorbic acid (AA) and 4-hexylresorcinol (4-HR) on pear polyphenoloxidase (PPO) activity and stability have been investigated in vitro. AA does not interact directly with PPO but ...prevents browning by reducing oxidized substrates. The 4-HR exerts a dual role on PPO. If no substrates are present, it interacts preferably with the deoxy form of PPO inactivating it. If substrates and 4-HR are both present they compete for the catalytic site. The 4-HR behaves then as a canonical enzyme inhibitor, binding to the met form of PPO. Simultaneous addition of 4-HR and AA has synergistic inhibition or inactivatory effects depending on the presence or the absence of PPO substrates.
The polyphenolic profile and antioxidant activity of peel, pomace, and juice of ‘Verde Doncella’, a Spanish apple cultivar, is presented. Phenolic profile of the worldwide cultivated ‘Red Delicious’ ...cultivar was used for comparison. Flavanols, hydroxycinamic acids, flavonols, phloridzin, procyanidin B2, and gallic acid were quantified by HPLC. Larger concentrations of polyphenolics were found in the peel, which is in agreement with the total phenolic content and antioxidant activity (FRAP) values. ‘Verde Doncella’ expressed lower concentrations of flavanols and quercetin derivates in peel, pomace, and juice when compared to ‘Red Delicious’. ‘Verde Doncella’ was richer in p-coumaric acid and procyanidn B2 in the peel.
Changes of viscosity, transmittance spectra and colour of Bajo Aragón extra virgin olive oil, during the frying process, were studied, comparing them to the changes that occur during the frying ...process of high oleic sunflower oil. The studied oil was obtained from Empeltre variety olives. These changes, due to the deterioration of the oil during this process, were monitored by polar compounds measurement. Polar compounds content increased linearly with the frying cycle in both types of oil; however, the increase was faster in high oleic sunflower oil. The olive oil’s transmittance spectra, after the frying process, proved that, not only do the peaks corresponding to the carotenoids and the chlorophyll disappear but also that transformation of the chlorophyll occured. In high oleic sunflower oil spectra there were no changes.
L∗ and
b∗ colour parameters, measured on the CIELAB colour scale, showed the following behaviour:
L∗ values increased for olive oil after frying while the opposite happened for high oleic sunflower oil. In the case of the
b∗ parameter, the result was the same in both cases: when fried, more green and yellow colours appeared. The viscosity of both oils showed a non-linear increase with number of frying operations, which may correspond to a polynomial relationship. Despite their similar contents of oleic acid, olive oil was more stable to oxidation and there were some physical differences between the two types of oil.
We have investigated the mechanism of action of 4-hexylresorcinol (4-HR) and ascorbic acid (AA) on the polyphenol oxidase (PPO) catalyzed oxidation of phenolic substrates. Incubation of PPO with 4-HR ...diminishes strongly PPO activity. This effect can be erroneously interpreted, due to the high affinity of 4-HR for PPO, as irreversible inactivation of PPO. However, PPO activity can be recovered by dialysis after incubation with 4-HR. 4-hexylresorcinol is a canonical enzyme inhibitor that binds preferentially to the oxy form of PPO. It is a mixed-type inhibitor, because it influences both apparent Vmax (1.26 compared with 0.4 units in the absence and presence of 4-HR, respectively) and Km values (0.28 mM compared with 0.97 mM in the absence and in the presence of 4-HR, respectively) of PPO. AA can prevent browning by 2 different mechanisms: In the absence of PPO substrates it inactivates PPO irreversibly, probably through binding to its active site, preferentially in its oxy form. In the presence of PPO substrates, AA reduces PPO oxidized reaction products, which results in a lag phase when measuring PPO activity by monitoring dark product formation but not when monitoring O₂ consumption. The simultaneous use of both 4-HR and AA on PPO results in additive prevention of browning.
The commercial potential of olive oils from three autochthonous olive varieties Bodocal, Racimilla and Negral from Aragón (Spain) has been examined. Physicochemical characteristics, sensory analysis, ...nutritional composition, color and pigments were considered. The three varieties are generally used for producing table olives or olive oil in coupages but not for the production of monovarietal virgin olive oil. The values of the physicochemical and sensory analysis for the three olive oils corresponded to extra virgin category, however important differences among the three oils were observed in relation to pigment content, color measurements and fatty acid and phenol and tocopherol composition. Several characteristics such as oil yield, fatty acid and phenol and tocopherol content and sensory profiles suggested that some of these oils are of a promising composition. The olive yield of the Bodocal variety was the lowest (17%) and its corresponding oil had the smallest oleic acid (69%), phenols (272 mg gallic acid/kg) and tocopherol (96 mg/kg) contents and not equilibrated sensory parameters. The main characteristics of the Racimilla variety were a very high oil yield (28%) with very high contents in oleic acid (79 %) and phenols (831 mg gallic acid/kg). The oil of the Negral variety had very equilibrated sensory properties and its oleic acid content (76%) was similar to that of Racimilla. Its phenol content (456 mg gallic acid/kg) was between that of the other two varieties and its tocopherol content (190 mg/kg) was the highest. Therefore, the two last varieties could be of great interest for producing monovarietal olive oils.
Three trials were conducted to determine the influence of the use of temperature control systems on physico-chemical characteristics and acrylamide formation in the domestic preparation of potatoes. ...French fries were pre-treated by soaking in water or acidified water, and then they were cooked using a range of home-cooking procedures. Soaking raw potatoes in acidified water (pH=3.17) before frying at a controlled temperature (180 degreesC) was the most efficient pretreatment for reducing acrylamide formation (76%). For the same temperature, roasted frozen par-fried potatoes contained less fat and acrylamide than similar pan-fried potatoes. Potatoes butter fried at 140degreesC had an acrylamide concentration similar to that of potatoes fried in oil at 180degreesC, but this value was reduced by 71% when the frying was carried out using a temperature control system. Controlling the frying temperature reduced acrylamide formation at all the temperatures studied. Keywords: acrylamide, frying, induction hob, temperature control, potatoes, home-cooking, pretreatments, roasting
This study investigated the acute blockade of endogenous melatonin (MLT) using Luzindole with or without systemic lipopolysaccharide (LPS) challenge and evaluated changes in inflammatory and ...oxidative stress markers in the mouse jejunum. Luzindole is an MT1/MT2 MLT receptor antagonist. Both receptors occur in the small intestine. Swiss mice were treated with either saline (0.35 mg/kg, ip), Luzindole (0.35 mg/kg, ip), LPS (1.25 mg/kg, ip), or Luzindole + LPS (0.35 and 1.25 mg/kg, ip, respectively). Jejunum samples were evaluated regarding intestinal morphometry, histopathological crypt scoring, and PAS-positive villus goblet cell counting. Inflammatory Iba-1, interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, nuclear factor (NF)-kB, myeloperoxidase (MPO), and oxidative stress (NP-SHs, catalase, MDA, nitrate/nitrite) markers were assessed. Mice treated with Luzindole, LPS, and Luzindole + LPS showed villus height shortening. Crypt damage was worse in the LPS group. Luzindole, LPS, and Luzindole + LPS reduced the PAS-goblet cell labeling and increased Iba-1-immunolabelled cells compared to the saline group. Immunoblotting for IL-1 beta, TNF-alpha, and NF-kB was greater in the Luzindole group. The LPS-challenged group showed higher MPO activity than the saline and Luzindole groups. Catalase was reduced in the Luzindole and Luzindole + LPS groups compared to saline. The Luzindole group showed an increase in NP-SHs, an effect related to compensatory GSH activity. The acute blockade of endogenous MLT with Luzindole induced early changes in inflammatory markers with altered intestinal morphology. The other non-detectable deleterious effects of Luzindole may be balanced by the unopposed direct action of MLT in immune cells bypassing the MT1/MT2 receptors. Key words: Luzindole; Melatonin; LPS; Inflammation; Oxidative stress; Intestine
PDF
