ning reactions during storage of low-moisture Australian sultanas: Effects of vine nitrogen nutrition on subsequent arginine-mediated Maillard reactions during storage of dried fruit
“…Proline is the main amino acid, together with arginine, in grape (). The initial rise could be related to the need for radical detoxification () due to strong oxidation, as emphasized by LOX activity, whereas the subsequent proline increase is related to the need for osmotic protection ( , ). 6 Proline content in Malvasia grape samples, plotted versus weight loss.…”
Malvasia (Vitis vinifera L.) grapes were harvested at 17.8% of soluble solids content (SSC) and placed inside an innovative dehydration room where temperature, relative humidity, and air flow were maintained, respectively, at 15 degrees C, 40%, and 1-1.5 m s(-1). Weight loss of bunches reached approximately 33% in 29 days. SSC increased inversely proportionally with the weight decrease, reaching at the end of experiment 23%. Abscisic acid (ABA) increased rapidly from around 29 to 80 microg g(-1) of dry weight at 11.7% of bunch weight loss and then declined gradually. Lipoxygenase (LOX) showed the same behavior as ABA, whereas alcohol dehydrogenase (ADH), read in the way of ethanol oxidation, increased continuously when the weight loss reached approximately 19.5%. In parallel with the activity of LOX, C6 compound [hexanal, hex-1-enol, (E)-hex-2-enal] concentrations reached a peak at 11.7% of weight loss, whereas ethanol and acetaldehyde increased with the increase of ADH and successively decrease and ethyl acetate increased. Proline increased initially as ABA and successively with the increase of ADH, 5.3-fold increase versus 4.2-fold increase of proteins. Postharvest dehydration of Malvasia grapes shows a biphasic pattern: a first metabolic stress response up to 11.7% of bunch weight loss and a second stress response beyond 19.5% of weight loss. The metabolic mechanism of these postharvest water stress responses is discussed.
“…Proline is the main amino acid, together with arginine, in grape (). The initial rise could be related to the need for radical detoxification () due to strong oxidation, as emphasized by LOX activity, whereas the subsequent proline increase is related to the need for osmotic protection ( , ). 6 Proline content in Malvasia grape samples, plotted versus weight loss.…”
Malvasia (Vitis vinifera L.) grapes were harvested at 17.8% of soluble solids content (SSC) and placed inside an innovative dehydration room where temperature, relative humidity, and air flow were maintained, respectively, at 15 degrees C, 40%, and 1-1.5 m s(-1). Weight loss of bunches reached approximately 33% in 29 days. SSC increased inversely proportionally with the weight decrease, reaching at the end of experiment 23%. Abscisic acid (ABA) increased rapidly from around 29 to 80 microg g(-1) of dry weight at 11.7% of bunch weight loss and then declined gradually. Lipoxygenase (LOX) showed the same behavior as ABA, whereas alcohol dehydrogenase (ADH), read in the way of ethanol oxidation, increased continuously when the weight loss reached approximately 19.5%. In parallel with the activity of LOX, C6 compound [hexanal, hex-1-enol, (E)-hex-2-enal] concentrations reached a peak at 11.7% of weight loss, whereas ethanol and acetaldehyde increased with the increase of ADH and successively decrease and ethyl acetate increased. Proline increased initially as ABA and successively with the increase of ADH, 5.3-fold increase versus 4.2-fold increase of proteins. Postharvest dehydration of Malvasia grapes shows a biphasic pattern: a first metabolic stress response up to 11.7% of bunch weight loss and a second stress response beyond 19.5% of weight loss. The metabolic mechanism of these postharvest water stress responses is discussed.
“…By comparison, in a storage study with sultanas, despite extensive formation of MRPs in emulsion-dried sultanas, the principle grape phenolic trans-caftaric was stable after 10 months at 30°C, and also under 'accelerated' oxidation conditions of 50°C for 12 days (Frank et al, 2005), providing supportive evidence for the storage stability of phenolics in emulsion-dried sultanas. In a further study with prunes, process-mediated decreases in the main phenolics, neochlorigenic acid and chlorigenic acid were minimal at 85°C but significant at 60°C, whereas destruction of anthocyanins was extensive at both temperatures.…”
Section: Effects Of Storage On Tpp Content and Aox Activitymentioning
“…The most distinctive step of the production process of this sweet white wine -previously described by Nicolosi Asmundo et al (1990) and by Muratore et al (2007) -is the off-vine drying of the grapes, gathered when they are fully ripe and then exposed to the sun on large mats made of bamboo canes. For the production of the traditional Malvasia delle Lipari passito wine, it is very important that bunches dehydrate gradually, safe from environmental conditions promoting the colonisation of pathogenic microorganisms like Botrytis cinerea and Penicillium expansum or favouring the excessive browning of the berries due to Maillard reactions which could take place during the off-vine drying at too high temperature (Frank et al, 2005;Moreno et al, 2007). Both these phenomena affect the grape aroma, one of the most important factors in determining wine flavour character and quality.…”
Section: Introductionmentioning
confidence: 99%
“…(2007)– is the off‐vine drying of the grapes, gathered when they are fully ripe and then exposed to the sun on large mats made of bamboo canes. For the production of the traditional Malvasia delle Lipari passito wine, it is very important that bunches dehydrate gradually, safe from environmental conditions promoting the colonisation of pathogenic microorganisms like Botrytis cinerea and Penicillium expansum or favouring the excessive browning of the berries due to Maillard reactions which could take place during the off‐vine drying at too high temperature (Frank et al. , 2005; Moreno et al.…”
This study evaluated the impact on free and bound volatiles of Malvasia delle Lipari passito wine of two
transformation variables at different stages of the winemaking process: different sun exposures of postharvested
grapes during drying and pre-fermentative cryomaceration. Wine volatiles were analysed by solidphase
extraction ???GC-MS (gas-chromatography/mass spectrometry) and odour by sensory descriptive
analysis. The off-vine bunches dried in shaded conditions (MLsh wine) and juice cryomaceration (6 C, 12 h)
of the dried grapes (MLc wine), both significantly affected the volatiles of Malvasia delle Lipari traditionally
produced (MLs wine). The MLsh wine was richest (67%) in free volatiles. Total bound terpenoids had a
higher level in the MLsh wine (20%). Total free volatiles of the cryomacerated wine (MLc) were higher
(45%) than those of MLs. Total bound volatiles were 36% higher in the cryomacerated sample. Sensory
analysis showed that compositional differences of the wine volatiles reflected on their odour character
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