Enzyme Pectin Methylesterase Research Articles

Thermosonication: a potential technique that influences the quality of grapefruit juice

SummaryThermosonication (TS) is an emerging nonthermal processing technique used for the liquid food preservation and is employed to improve the quality and acceptability of grapefruit juice. In this study, fresh grapefruit juice samples were subjected to TS treatment in an ultrasonic cleaner with different processing variables, including temperature (20, 30, 40, 50 and 60 °C), frequency (28 kHz), power (70%, 420 W) and processing time (30 and 60 min) for bioactive compounds, inactivation of enzymes pectin methylesterase (PME), peroxidase (POD) and polyphenolase (PPO) and micro‐organisms (total plate count, yeasts and moulds). The micro‐organism activity was completely inactivated in the treatment (60 °C for 60 min). The TS treatment at 60 °C for 60 min exposure reduced PME, PPO and POD activity by 91%, 90% and 89%, respectively. Results indicate that the advantages of TS for grapefruit juice processing at low temperature could enhance the inactivation of enzymes and micro‐organisms and it can be used as a potential technique to obtain better results as compared to alone.

Impact of Power Ultrasound on the Quality of Fruits and Vegetables During Dehydration

In the present work, the influence of power ultrasound (US) on the quality of fruits and vegetables during both the pre-treatment and drying has been evaluated. Chemical indicators such as pectinmethyl esterase and peroxidase enzymes, vitamin C, carbohydrates, proteins, polyphenols and 2-furoylmethylamino acids (indicators of the early stages of Maillard reaction) have been studied. In addition, rehydration capacity, leaching losses and shrinkage and organoleptic characteristics of the final product have also been assessed. During blanching, similar leaching losses and enzyme inactivation were found in low temperature and prolonged conventional treatments and in US processes, but with a significant reduction in the time for the latter. Finally, application of US in drying of carrots and strawberries originated significant reductions in processing time, while providing high quality end-products. The quality was higher as compared to marketed products and superior or equivalent to samples obtained under similar conditions in a prototype convective dryer, and, in the case of some indicators, similar to that of freeze-dried samples.

Effect of High Pressure Processing on Rheological Properties, Pectinmethylesterase Activity and Microbiological Characteristics of Aloe Vera (Aloe barbadensis Miller) Juice

Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheological properties, pectinmethylesterase (PME) enzyme activity and microbiological characteristics of aloe vera juice was studied. A quadratic model was developed for rheological parameters and it was found that pressure level had the most significant effect on all the responses (p < 0.05) followed by pH and dwell time. Pectinmethylesterase activity was evaluated and a maximum of up to 30% inactivation was obtained. Microbial analysis of high pressure treated samples revealed that samples treated at 400 MPa for 20 min at pH 4 reduced microbial counts to <10 cfu mL−1 achieving up to 5.66 log cycle reduction.

Influence of Processing Additives on the Quality and Stability of Dried Papaya Obtained by Osmotic Dehydration and Conventional Air Drying

The combination of osmotic dehydration and hot air drying (OD/HA) is an industrial alternative to papaya production, but tissue softening and color loss are technological problems. The objective of this work was to study, during OD/HA processing of papaya (Formosa cultivar), the influence of organic acids (citric and lactic), calcium salts (lactate and chloride), and the enzyme pectinmethylesterase (PME) on the texture, color, and sensory characteristics of the product. The stability of the products treated with lactic acid/calcium chloride, PME/calcium chloride, and the standard sample (without additives) was evaluated at 25 and 35°C for up to 100 days, analyzing vitamin C and color degradation. Light microscopy analysis performed at the beginning of stability study showed that the additives better preserved the cell structure. The use of lactic acid/calcium chloride maintained the color of the dried papaya, but the additives did not have an effect on vitamin C degradation. The variations in the chromaticity parameters (b* and a*) were adjusted to zero- and first-order kinetic models, respectively, with Q 10 values ranging between 0.88 and 2.30 and R 2 ∼ 0.90. The combination of lactic acid/calcium chloride resulted in higher sensory acceptance and color stability of dried papaya during storage.

Effect of different packaging films on shelf life and quality of peach under super and ordinary market conditions.

Peach (Prunus persica L. Batsch) fruits of cultivar 'Shan-i-Punjab' were harvested at colour break stage and packed in paper moulded trays followed by wrapping with different packaging films viz. cryovac heat shrinkable RD-106, cling and low density polyethylene (LDPE) film. After packaging, the fruits were stored under two different conditions i.e. super-market conditions (18-20°C; 90-95% RH) and ordinary market conditions (28-30°C; 60-65% RH). The fruits were evaluated for various quality attributes periodically. The shrink film helped in reducing the loss in weight, firmness, decay incidence and maintained the various qualities attributes like total soluble solids, sugars, acidity and ascorbic acid content of the fruits during shelf-life better than unwrapped control fruits. The pectin methyl esterase enzyme activity was also found to be lower in shrink film packed fruits over the unwrapped control fruits. The in-package gaseous composition (O2 and CO2) in shrink film packed fruits was found to be at desired level which resulted in maintenance of pleasant flavour of the fruits. On the other hand LDPE film accumulated very high level of CO2, which led to formation of fermenting odour and decay of fruits in the package. The data revealed that RD-106 film proved quite effective in prolonging the shelf-life and maintaining the quality of peach fruits for 9 and 4days under super market conditions (SMC) and ordinary market conditions (OMC), respectively as against 6 and 2days only in case of unpacked control fruits under both the marketing conditions. The results suggest that shrink film could be used in packaging of peach without negative effects on quality.

Comparative evaluation of enzyme activities and phenol content of Irish potato (&lt;i&gt;Solanum tuberosum&lt;/i&gt;) grown under EM and IMO manures Bokashi

Irish potato (Solanum tuberosum) is one of the world’s most consumed staple. In order to develop natural fertilizers to increase Irish potato yield, we assessed the use of manures (EM Bokashi and IMO Bokashi, which are cocktail of beneficial bacteria; used as a soil remediation and health measure in many organic farms) on potato tubers in Bambili village in the North West Region of Cameroon, through evaluating biochemical parameters such as the phenol content, and the activities of peroxidase (POX), polyphenol oxidase (PPO) and pectinmethyl esterase (PME) enzymes. In this respect, a land of 18 x 8 m2 with six plots of 18 beds each was used to cultivate the plant. The plant length and weight of tubers were quantified in the field. Relative to controls (55.96 ± 25.83 cm), both EM and IMO Bokashi produced longer plants (73.85 ± 27.74 cm and 65.25 ± 23.45 cm respectively) but between experimental plants, EM Bokashi led to heavier tuber weights (234 ± 132 g) compared to IMO Bokashi. Interestingly, biochemical analyses showed the highest phenolic content and PME activity in plants treated with EM Bokashi. All treatments significantly increased POX activity while they decreased PPO activity. In addition, significant and positive correlations (P &lt; 0.01) were observed between stem length and PME activity independent of treatment. Plant treated with IMO Bokashi had significant and positive correlations between stem length and weight on the one hand and between stem length and biochemical parameters on the other hand. These findings showed that EM and IMO Bokashi treatments increased the phenol content, PME, PPO and POX activities during the growth of S. tuberosum and can thus be used to improve its growth and productivity.Keywords: Solanum tuberosum, phenol content, biochemical markers, Bokashi manures, productivity

Nitric oxide inhibits activities of PAL and PME enzymes and reduces chilling injury in ‘Santa Rosa’ Japanese plum (Prunus salicina Lindell)

Studies were carried out to observe the effect of sodium nitroprusside (SNP) treatment (source of nitric oxide) on chilling injury, electrolyte leakage, malondialdehyde (MDA) content, phenylalanine ammonia lyase (PAL) and pectin methyl esterase (PME) activities during low temperature storage of Japanese plums cv. ‘Santa Rosa’. All SNP treatments significantly alleviated CI symptoms during entire period of cold storage. Among different treatments, fruits treated with SNP (0.5 mM) showed 71 % lower incidence of CI than control. Minimum electrolyte leakage (49 %), PAL (53.6μmoles of cinnamic acid produced min−1 g−1FW) and PME activity (0.36 μmol min−1 g−1FW) were observed in 0.5 mM SNP treated plums and the maximum in control. The maximum retention of ascorbic acid (25.6 mg/100 g pulp) and antioxidant capacity (14.7 μmol Trolox g−1) was also exhibited by 0.5 mM SNP treated plums. Lowest MDA content (8.17 nmol g−1 FW) and anthocyanin content (592.7 mg/kg FW) were also found in the fruits treated with 0.5 mM SNP. Thus, it can be concluded that SNP is an easy method for application of nitric oxide to maintain fruit quality and extending shelf life by inhibiting fruit softening through interfering with PAL and PME activities during cold storage of ‘Santa Rosa’ plums.

Pectin Metabolism and Assembly in the Cell Wall of the Charophyte Green Alga Penium margaritaceum

The pectin polymer homogalacturonan (HG) is a major component of land plant cell walls and is especially abundant in the middle lamella. Current models suggest that HG is deposited into the wall as a highly methylesterified polymer, demethylesterified by pectin methylesterase enzymes and cross-linked by calcium ions to form a gel. However, this idea is based largely on indirect evidence and in vitro studies. We took advantage of the wall architecture of the unicellular alga Penium margaritaceum, which forms an elaborate calcium cross-linked HG-rich lattice on its cell surface, to test this model and other aspects of pectin dynamics. Studies of live cells and microscopic imaging of wall domains confirmed that the degree of methylesterification and sufficient levels of calcium are critical for lattice formation in vivo. Pectinase treatments of live cells and immunological studies suggested the presence of another class of pectin polymer, rhamnogalacturonan I, and indicated its colocalization and structural association with HG. Carbohydrate microarray analysis of the walls of P. margaritaceum, Physcomitrella patens, and Arabidopsis (Arabidopsis thaliana) further suggested the conservation of pectin organization and interpolymer associations in the walls of green plants. The individual constituent HG polymers also have a similar size and branched structure to those of embryophytes. The HG-rich lattice of P. margaritaceum, a member of the charophyte green algae, the immediate ancestors of land plants, was shown to be important for cell adhesion. Therefore, the calcium-HG gel at the cell surface may represent an early evolutionary innovation that paved the way for an adhesive middle lamella in multicellular land plants.

English

An experiment was conducted during the year 2010 to evaluate the effect of the treatment with 1-methylcyclopropene (1-MCP) on the ripening process of sapodilla fruits, after refrigeration. The fruits were exposed to 0 and 1 &micro;L/L of 1-MCP for 24 h in airtight chambers at 25&deg;C, after which they were stored at 16&deg;C for four periods of refrigeration (0, 11, 18 and 25 days). At the end of each refrigeration period, the samples were allowed to ripe at 25&deg;C. The results demonstrated the effectiveness of 1-MCP in significantly delaying (P&le;0.05) the ripening process of sapodilla fruits and extending the post-harvest life to 28 days. It was possible to observe a reduction and delay in the climacteric maximums of ethylene and respiration, and a delay in the maximum activity of the pectin methyl esterase enzyme (PME), while weight loss was also reduced. In general, the quality characteristics of ripe fruits were maintained, except for a significant increase in the total soluble solids content of the fruits treated. These results indicate that the treatment with 1-MCP, combined with refrigeration, is an adequate alternative for increasing the shelf life of sapodilla with the aim of facilitating its commercialization. Key words: Sapodilla, 1-methylcyclopropene, ripening, post-harvest, shelf life, refrigeration.

Postharvest Parameters of the “Fuerte” Avocado When Refrigerated in Different Modified Atmospheres

The objective of this work was to evaluate the refrigerated “Fuerte” avocados stored in different modified active atmospheres. The fruits were wrapped in bags made of nylon plus polyethylene and submitted to the following atmospheres: (I) mixture of ambient gases (0.03% CO2 and 21.0% O2); (II) 5.0% CO2 and 4.0% O2; (III) 6.0% CO2 and 4.0% O2; (IV) 7.0% CO2 and 4.0% O2; and (V) 8.0% CO2 and 4.0% O2. The bags containing the fruits were stored at 10C ± 1 and 90 ± 5% relative humidity for 25 days and were analyzed every 5 days for weight loss, respiratory activity, pH, firmness, titratable acidity, soluble solids, and activities of the enzymes pectin methylesterase and polygalacturonase. The atmosphere of 7.0% CO2 and 4.0% O2 was the most effective in limiting the weight loss and the production of CO2. Practical Applications This research will have the practical application of showing producers and suppliers of avocados the best ways to store “Fuerte” avocados. It shows that a modified atmosphere of 7.0% CO2 and 4.0% O2 was the most effective in minimizing weight loss and CO2 production when refrigerated.

Effect of processing on physicochemical composition, bioactive compounds and enzymatic activity of yellow mombin (Spondias mombin L.) tropical juice.

Yellow mombin (Spondias mombin, L.) is a tropical fruit that presents exotic taste and aroma, being source of carotenoids and phenolics compounds. It presents a good potential for processing, despite some restriction related with the presence of high amounts of peroxidase (POD) and pectinmethylesterase (PME) which can cause sensory changes in the product. This work addresses the evaluation of changes in POD and PME enzyme activity during the traditional industrial processing used to produce tropical juices in Brazil. The enzyme activity was determined after the main steps of the processing: fruit pulping, homogenization and pasteurization. Although both enzymes presented significant activity loss during processing, the final product showed residual activity for PME (25%) and POD (2.5%). PME showed to be more thermal resistant than POD in yellow mombin juice. Considering the compounds with antioxidant activity, yellow mombin presented high amounts of carotenoids and phenolics when compared to other tropical fruits such as passion fruit and pineapple. Although the processing of the fruit resulted in significative phenolic loss, the carotenoids content was not affected significantly by the processing.

Evaluation of pectinolytic activities for oenological uses from psychrotrophic yeasts

Of the twenty-three morphotypes of yeasts isolated from soil capable of utilizing pectin as sole carbon source at 6°C, two yeast isolates, one psychrotolerant (PT1) and one psychrophilic (SPY11), were selected according to their ability to secrete pectinolytic enzymes under some oenological conditions (temperature 6 and 12°C and pH 3.5) and ability or inability to grow above 20°C, respectively. As compared to their optimal activity, the three pectinolytic enzymes viz., pectin methyl esterase (PME), endopolygalacturonase (endo-PG) and exopolygalacturonase (exo-PG) isolated and assayed at pH 3.5 from PT1 were found to retain 39, 60 and 60% activity at 12°C and 40, 79 and 74% activity at 28°C, respectively. Likewise, the enzymes PME and endo-PG at pH 3.5 from SPY11 displayed 46 and 86% activity at 12°C and 50 and 60% activity at 28°C, respectively. All these enzymes showed 20-90% of residual activity at pH 3.5 and 6°C. The yeast isolates PT1 and SPY11 were identified as Rhodotorula mucilaginosa and Cystofilobasidium capitatum, respectively, on the basis of morphological, physiological and molecular characteristics. This study presents the first report on pectinolytic activities under major oenological conditions from psychrotolerant isolate R. mucilaginosa PT1 and psychrophilic isolate C. capitatum SPY11. The cold-active pectinolytic enzymes (PME, endo-PG and exo-PG) from the newly isolated and identified psychrophilic yeast Cystofilobasidium capitatum SPY11 and psychrotolerant yeast Rhodotorula mucilaginosa PT1that exhibited 50-80% of their optimum activity under some major oenological conditions pH (3.5) and temperatures (6 and 12°C) could be applied to wine production and juice clarification at low temperature. The psychrotrophic yeasts themselves could be applied to cold process for the production of enzymes thus saving cost of energy and protecting process from contamination.

HIDROLISIS GUGUS METOKSIL PEKTIN AMPAS TEBU UNTUK MENGHASILKAN BIOMETANOL

&lt;p&gt;Methanol is a potential in two areas, namely as fuel cells and biodiesel. Among the many biomass, pectin is one of the best for the production of methanol. The purpose of this study was to determine the influence of pectin methyl esterase enzyme concentration (PME) group metoksil rough on pectin hydrolysis of bagasse to produce the highest levels of biometanol.&lt;/p&gt; &lt;p&gt;Methods This study includes the preparation of the bagasse, further hydrolysis using crude extract of the enzyme pectin methyl esterase (PMEs) resulting from bacterial culture Bacillus subtilis at Borth Nutrient media (NB) with 1% pectin. Hydrolysis of Metoksil groups of poligalakturonat acid in the pectin bagasse to obtain the concentration of methanol to vary the enzyme crude extract PMEs. Concentration of crude enzyme extract PMEs used was 10%, 15%, 20% and 25% in 24-hour incubation with 2 repetitions performed. The resulting methanol levels were analyzed using GC (Gas Chromatography).&lt;/p&gt; The results of this study concluded that allowing the concentration used for hydrolysis of bagasse to produce methanol using crude enzyme from Bacillus subtilis (PMEs) is 10% with a methanol content of 0.02%.

Influence of different desapping agents on the incidence of sapburn, ripening behaviour and quality of mango.

Sapburn injury in mango is regarded as the most serious problem as it reduces the aesthetic appeal and downgrade the fruit quality with considerable economic losses. For the control of sapburn injury, physiologically mature mango fruits of cv. Chausa were harvested along with 5-8cm stalk attached. Immediately after harvesting, fruits were de-stemmed and treated with different desapping agent solutions [calcium hydroxide (1%), sodium hydroxide (1%), alum (0.5 and 1%)] by dipping them for 5min. In control fruits, the pedicels were removed and sap was allowed to spread freely over the fruit surface. After treatment application, fruits were air-dried and stored at ambient condition (30 ± 2°C) for 12days. Among the treatments, fruits desapped with sodium hydroxide (1%) showed significantly lower (7.6-fold) sapburn injury followed by alum (0.5%) treatment than control. Respiration and ethylene evolution rates were also significantly suppressed and delayed with sodium hydroxide (1%) treatment. Fruit firmness and functional properties like, antioxidant capacity, total carotenoids and total phenolics content were also found higher in sodium hydroxide (1%) treated fruits. Pectin methyl esterase and polygalacturonase enzyme activity were recorded higher in fruits of control and calcium hydroxide treatment however; it was suppressed by sodium hydroxide and alum treatments. Fruit quality parameters like color, total soluble solids, titratable acidity and total sugars content were found higher in calcium hydroxide and sodium hydroxide treated fruits than control and alum treated fruits.

Physiological changes in Karanda (Carissa carandus L.) fruit during growth and ripening

PurposeIncreased reliance on major food crops has caused shrinking of the food basket. Therefore, the aim of the present study is to introduce underutilised fruit of Karanda (Carissa carandus L.) for its commercial exploitation.Design/methodology/approachThe present study elucidates the physiological changes that prevail in the fruits of Karanda during its successive stages of growth and ripening. Changes in sugars, starch, proteins, phenols, amino acids, role of various enzymes and rate of ethylene and respiration has been used as parameters to access the physiological changes taking place.FindingsNotable change was observed in its colour from green to deep blue/black, accumulation of sugars and proteins, degradation of starch, phenols and free amino acids. Cell wall degrading enzymes (polygalactouronase and pectin methylesterase) and antioxidant enzymes (catalase and peroxidase) showed their active role, while that of cell wall degrading enzyme cellulase and hydrolyzing enzymes (amylase and invertase) were not active during the growth and ripening of the fruit. Increased levels of respiration and ethylene production determined it to be a climacteric type of fruit.Research limitations/implicationsThe study does not provide information regarding the other nutritional parameters of the fruits like vitamins and minerals.Originality/valueThe physiological changes in relation to growth and ripening would be useful in determining the maturity indices for harvesting and utilization of this underutilised Karanda fruit.

FLYING SAUCER1 Is a Transmembrane RING E3 Ubiquitin Ligase That Regulates the Degree of Pectin Methylesterification inArabidopsisSeed Mucilage

Pectins are complex polysaccharides that form the gel matrix of the primary cell wall and are abundant in the middle lamella that holds plant cells together. Their degree of methylesterification (DM) impacts wall strength and cell adhesion since unesterified pectin regions can cross-link via Ca(2+) ions to form stronger gels. Here, we characterize flying saucer1 (fly1), a novel Arabidopsis thaliana seed coat mutant, which displays primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. These defects appear to result from a lower DM in mucilage and are enhanced by the addition of Ca(2+) or completely rescued using alkaline Ca(2+) chelators. FLY1 encodes a transmembrane protein with a RING-H2 domain that has in vitro E3 ubiquitin ligase activity. FLY1 is orthologous to TRANSMEMBRANE UBIQUITIN LIGASE1, a Golgi-localized E3 ligase involved in the quality control of membrane proteins in yeast. However, FLY1-yellow fluorescent protein (YFP) fusions are localized in punctae that are predominantly distinct from the Golgi and the trans-Golgi network/early endosome in the seed coat epidermis. Wortmannin treatment, which induces the fusion of late endosomes in plants, resulted in enlarged FLY1-YFP bodies. We propose that FLY1 regulates the DM of pectin in mucilage, potentially by recycling pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells.

Avaliação da atividade das enzimas pectina metilesterase e β-Galactosidase em mamões cv. Golden armazenados sob diferentes concentrações de oxigênio

Este trabalho foi realizado com o objetivo de avaliar o efeito de atmosferas controladas contendo diferentes concentrações de oxigênio sobre a atividade das enzimas β-galactosidase e pectina metilesterase, e sobre a cor da casca e a firmeza da polpa de mamões 'Golden'. Os frutos foram mantidos por 36 dias, nas seguintes atmosferas controladas: 1% de O2 e 0,03% CO2 com adsorvedor de etileno, 3% de O2 e 0,03% de CO2 com adsorvedor de etileno, 5% O2 e 0,03% de CO2 com adsorvedor de etileno e atmosfera ambiente sem adsorvedor de etileno. A UR e a temperatura foram mantidas entre 85-95% e a 13º C, respectivamente. Os frutos estocados sob atmosfera de 1% de O2 e 0,03% CO2 apresentaram retardamento nas atividades das enzimas β-galactosidase e pectina metilesterase comparado com os frutos estocados nas outras atmosferas avaliadas. Os frutos armazenados sob atmosfera de 1% de O2 e 0,03% O2 também apresentaram atraso no desenvolvimento da cor da casca e amolecimento da polpa.

POLYGALACTURONASE AND PECTIN METHYLESTERASE ACTIVITIES OF CaCl&lt;sub&gt;2&lt;/sub&gt; TREATED RED-FLESHED DRAGON FRUIT (&lt;i&gt;HYLOCEREUS POLYRHIZUS&lt;/i&gt;) HARVESTED AT DIFFERENT MATURITY

Fruits harvested at different maturity possess different biochemical constituents and physiological properties that make the fruits may react somewhat differently to the postharvest treatment. A study to examine the activity of Polygalacturonase (PG) and Pectin Methylesterase (PME) enzymes during storage in dragon fruit (Hylocereus polyrhizus) harvested at 28 days (Index 3) and 34 days (Index 5) after anthesis and postharvest treated with 0, 2.5, 5.0 and 7.5 g L-1 CaCl2 was performed. The PG activity was lower in younger fruit and vice-versa for PME activity. Increasing concentration of CaCl2 effectively reduced the activity of both enzymes. PG activity for fruit treated with 0, 5 and 7.5 g L-1 CaCl2 increased linearly with the time of storage while its activity for the fruit treated with 2.5 g L-1 CaCl2 was lower at the beginning of storage. PG activity of Index 5 fruits increased almost linearly during storage while its activity in Index 3 fruits was low at the early days of storage and later continued to increase until day seven. At both maturity indices, the PME activity was low at the early days of storage and later continued to increase until day seven. Overall, results obtained indicated that CaCl2 postharvest treatment reduced both PME and PG activities thus slowing down the softening process giving an evident that calcium possess a distinguishable role in the reducing softening of fruit, regardless of maturity index.

Pectinmethylesterase extraction from orange solid wastes: Optimization and comparison between conventional and ultrasound-assisted treatments

During orange juice production, a half of fresh oranges weight is considered as production waste (peels, pulp, seeds, orange leaves and damaged orange fruits). An alternative for the management of these wastes is their treatment by addition of lime and a latter pressing, obtaining a press cake and a press liquor rich in sugars (10° Brix) and citric acid, protein, pectin and ethanol. For non-thermal concentration of press liquor to obtain citruss molasses (65°-70° Brix), the removal of pectin is necessary. Traditionally, depectinization of juices has been done by using pectinmethylesterase (PME) enzymes from external sources. In this work it performed the extraction of PME enzymes from orange peels to obtain the optimum extraction conditions. Two different methods of solventextraction were compared (conventional andultrasound-assisted methods). For the conventional extraction experiments, a central composite design with three variables ([NaCl], pH and time) and five replicates of the center point was used. For ultrasound-assisted extraction, experiments were done at pH = 5.5 and [NaCl] = 1.25M), varying extraction time (1-30 min). Response variables were PME activity, protein content and a ratio between them, named PME effectiveness (ηPME). At the same experimental conditions (pH =5.5, [NaCl] = 1.25 M, t = 15 min) it was found that conventional extractions led to slightly better results in terms of ηPME than ultrasound-assisted extraction method.

Inactivación Térmica de Pectinmetilesterasa en Tomate de Árbol (Solanum betaceum)

The effect of batch thermal processing on the residual activity of pectinmethylesterase enzyme (PME) in tree tomato (Solanum betaceum) was studied. Batch processes were conducted at temperatures between 40 and 90°C and exposure times from 5 to 20s. Residual enzyme activity was spectrophotometrically measured at 620 nm wavelength. The protein content was determined according to Bradfords dye binding method. The thermal treatment applied to 60°C for 20 seconds exposure time, reduced the residual activity of PME to 10% avoiding phase separation. It is concluded that the thermal treatment applied caused a decrease on enzyme content to 28% from initial content.