2. 58 A. Vega-Gálvez et al. / Innovative Food Science and Emerging Technologies 13 (2012) 57–63
replace, enhance or modify conventional techniques of food produc- spread on one DRBC plate. Plates were then incubated at 25 °C for 3–
tion (Lewicki & Lenart, 2006; Rastogi, Angersbach, & Knorr, 2000; 5 days, and plates with 30–300 colonies were counted. Microbial
Vega-Gálvez et al., 2011; Yucel, Alpas, & Bayindirli, 2010). In addition data were transformed into logarithms of the number of colony-
to quality improvements and consumer benefits by gentle microbial forming units (log CFU/mL). Detection limit was 10 CFU/mL
inactivation and improvement of mass transfer processes, HHP has according to WHO (1999).
the potential to improve energy efficiency and sustainability of food
production (Donsí, Ferrari, & Maresca, 2010; Rastogi et al., 2000; 2.3.2. Microbial growth curve modeling
Toepfl, Mathys, Heinz, & Knorr, 2006). Moreover, changes in food Predictive microbiology is a useful tool to determine shelf life of
texture during HHP are strongly related to transformations in cell wall food products. The experimental data obtained were fitted to the re-
polymers due to enzymatic and non-enzymatic reactions, being a parameterized version of the modified Gompertz equation according
major challenge to use this novel technology to adjust raw materials, to the work of Briones, Reyes, Tabilo-Munizaga, and Pérez-Won
ingredients and processes to improve texture of processed plant based (2010).
foods (Perera, Gamage, Wakeling, Gamlath, & Versteeg, 2010; Sila et
al., 2008). & & ! ''
λ−SL
Therefore, the aim of this work was to study the effect of high log ðNðt ÞÞ = logðN max Þ−A⋅ exp − exp ðμ max ⋅2:7182Þ⋅ +1
hydrostatic pressure on quality indices of A. vera gel including & & ! ''A
λ−t
antioxidant capacity, color, polysaccharides, vitamins C and E, poly- + A exp − exp ðμ max ⋅2:7182Þ +1 ð1Þ
A
phenolics and texture as well as microbiological growth after 60 days
storage.
where N(t) is the viable cell concentration at time t. A is related to
2. Materials and methods the difference decimal logarithm of maximum bacterial growth
attained at the stationary phase and decimal logarithm of the
2.1. Sample preparation and high hydrostatic pressure treatment initial value of cell concentration, μmax is the maximal specific
growth rate, λ is the lag time, Nmax is the microbial threshold
The whole fresh leaves of A. vera were provided by the INIA- value, SL is the microbiological acceptability limit (i.e., the time at
Intihuasi, city of Coquimbo, Chile. Homogeneous leaves were selected which N(t) is equal to Nmax), and t is the storage time. The value of
according to size, color and freshness. Acibar (a yellow colored liquid) N max was set to 1 × 10 2 CFU/g for both mesophilic aerobic
was extracted by cutting the base of the leaves and allowing them to microorganisms and moulds and yeasts. This value is considered
drain vertically for 1 h. The epidermis was then separated from the as the upper acceptable limit for A. vera gel according to the World
gel, which was extracted and homogenized by a Phillips Electric Health Organization (WHO, 1999).
blender (HR1720, Amsterdam, The Netherlands). Samples of 25 mL The modified Gompertz equation was fitted to microbial data
were packaged into low density polyethylene bags. Then, they were using the nonlinear regression modulus of the GraphPad Prism v. 4.03
placed in a cylindrical loading container at room temperature and (GraphPad Software, Inc., San Diego, CA, USA). The goodness of fit was
pressurized at 300, 400 and 500 MPa during 1, 3 and 5 min for each evaluated using the coefficient of determination (R 2).
treatment and compared to untreated A. vera gel (control). Water was
employed as pressure-transmitting medium, working at 17 MPa/s 2.3.3. Determination of DPPH radical scavenging activity
ramp rate; decompression time was less than 5 s. A 2 L processing unit Free radical scavenging activity of the samples was determined
(Avure Technologies Incorporated, Kent WA, USA) was used to using the 2,2-diphenyl-2-picrylhydrazyl (DPPH) method (Turkmen,
pressurize the aloe samples. Then, they were removed and stored Sari, & Velioglu, 2005). Different dilutions of the extracts were
until further processing. prepared in triplicate. An aliquot of 2 mL of 0.15 mM DPPH radical in
ethanol was added to a test tube with 1 mL of the sample extract. The
2.2. Storage and sampling of processed juice reaction mixture was vortex-mixed for 30 s and left to stand at room
temperature in the dark for 20 min. The absorbance was measured at
Pressurized samples were stored at 4 °C. Quality and microbiolog- 517 nm, using a spectrophotometer (Spectronic® 20 Genesys™, IL,
ical analyses were performed immediately after processing and at USA). 80% (v/v) ethanol was used to calibrate the spectrophotometer.
intervals for up to 60 days storage. For all samples, three different Control sample was prepared without adding extract. All solvents and
batches were considered. reagents were purchased from Sigma (Sigma Chemical CO., St. Louis,
MO, USA). Total antioxidant activity (TAA) was expressed as the
2.3. Quality parameters percentage inhibition of the DPPH radical and was determined by
Eq. (2):
2.3.1. Microbiological analysis
The samples were analyzed for numbers of mesophilic aerobic
Abssample
microorganisms (MAM) and moulds and yeasts (MY). Twenty five % TAA = 1− × 100: ð2Þ
Abscontrol
mL or grams of each sample was obtained aseptically and
homogenized with a 225 mL peptone saline solution 0.1% (Difco,
Detroit, USA) in a filter stomacher bag using a Stomacher®
(Biocheck, S.A., Barcelona, Spain) at 240 rpm for 60 s. Further Where TAA is the total antioxidant activity and Abs is the
decimal dilutions were made with the same diluent, and duplicates absorbance. IC50, which is the concentration required to obtain a
of at least three appropriate dilutions were plated on appropriate 50% antioxidant capacity, is typically employed to express the
media. In order to enumerate the mesophilic aerobic microorgan- antioxidant activity and to compare the antioxidant capacity of
isms, 1 mL of each dilution was pour-plated in Plate Count Agar various samples. IC50 was determined from a graph of antioxidant
(PCA, Difco, Detroit, USA). After incubation at 30 °C for 72 h, plates capacity (%) against extract concentration (μg/mL sample).
with 30–300 colonies were counted. To count the moulds and
yeasts, 1 mL of the initial (10 − 1) dilution was spread on three plates 2.3.4. Determination of total polyphenolics (TPP)
(0.3, 0.3 and 0.4 mL) of Dicloran Rose Bengal Chloramphenicol TPP were determined colorimetrically using the Folin-Ciocalteau
(DRBC, Difco, Detroit, USA) agar, and 0.1 mL of each subsequent was reagent (FC) according to previous work with modifications (Chuah
3. A. Vega-Gálvez et al. / Innovative Food Science and Emerging Technologies 13 (2012) 57–63 59
et al., 2008). 0.5 mL aliquot of the aloe gel extract solution was averaged. Total color difference (ΔE) was calculated using Eq. (3),
transferred to a glass tube; 0.5 mL of reactive FC was added after 5 min where L0, a0 and b0 are the control values for fresh samples.
with 2 mL of Na2CO3 solution (200 mg/mL) and shaken. The sample
hÀ Á2 À Á2 À Á2 i0:5
aÃ−a0 + bÃ−b0 + LÃ−L0
was then mixed on a vortex mixer and the reaction proceeded for
ΔE = ð3Þ
15 min at ambient temperature. Then, 10 mL of ultra-pure water was
added and the formed precipitate was removed by centrifugation
during 5 min at 4000 ×g. Finally, the absorbance was measured in a
spectrophotometer (Spectronic® 20 Genesys™, IL, USA) at 725 nm 2.4. Statistical analysis
and compared to a gallic acid (GA) calibration curve. Results were
expressed as mg GA/100 g dry matter. All reagents were purchased Two-way analysis of variance (ANOVA) (Statgraphics Plus® 5.1
from Merck (Merck KGaA, Darmstadt, Germany). All measurements software, Statistical Graphics Corp., Herndon, USA) was used to
were done in triplicate. indicate significant differences among samples. Significance testing
was performed using Fisher's least significant difference (LSD) test;
2.3.5. Determination of vitamin C differences were taken as statistically significant when P b 0.05. The
L-Ascorbic acid was determined by the 2,6 dichlorophenol- Multiple Range Test (MRT) included in the statistical program was
indophenol (Merck KGaA, Darmstadt, Germany) tritimetric meth- used to test the existence of homogeneous groups within each of the
od according to AOAC method no. 967.21 (AOAC, 2000). A total of parameters analyzed.
10 ± 0.1 g of triturated sample were weighed, filtered, and diluted
to a volume of 50 mL. All measurements were done in triplicate. 3. Results and discussion
Vitamin C content was expressed as mg vit C/100 g dry matter.
3.1. Effect of HHP on microbiological behavior: application of Gompertz
2.3.6. Determination of vitamin E equation
The vitamin E content was determined by means of the
HPLC/fluorescence method described by Ubaldi, Delbono, Fusari, and The microbial load of the gel subjected to high hydrostatic
Serventi (2005). A liquid chromatograph (Shimadzu Instruments, Inc., pressure treatments (300, 400 and 500 MPa/1, 3 and 5 min) was
Shimadzu LC-10 AD) was used for all determinations. α-Tocopherol investigated. The initial microbial load of fresh A. vera gel (control)
was monitored with a fluorescence detector (Shimadzu Instruments, was 1.95 ± 0.048 and 2.37 ± 0.140 log CFU/mL for aerobic meso-
Inc., Shimadzu RF-10 A xL). All measurements were done in triplicate. philic microorganisms (AMM) and yeasts (Y), respectively. Moulds
Vitamin E content was expressed as mg Vit. E/100 g d.m. were not detected. Fig. 1(A-B) showed the population change of
both AMM and Y of samples treated at 300 MPa/1 min. The
2.3.7. Determination of firmness untreated samples did not meet the microbiological requirements
Firmness, which is the maximum force applied to puncture the according to WHO (WHO, World Health Organization, 1999)
samples, was measured as an indicator of texture. Firmness of samples (AMM N2.0 log CFU/mL; Y N2.0 log CFU/mL). In the case of samples
was measured using a Texture Analyzer (Texture Technologies Corp., treated at 300 MPa during 3 and 5 min, microbiological growth
TA, XT2, Scardale, NY, USA). The puncture diameter was 2 mm, with a was observed at the end of the storage (60 days). In addition,
travel distance of 20 mm and 1.7 mm s − 1 test speed. The maximum samples treated at 400 and 500 MPa during 1, 3 and 5 min had
force was measured by making one puncture in each sample, using 10 undetectable levels of microorganisms on PCA (b10 CFU/mL).
slabs per treatment. The mean value of maximum firmness for each These results were comparable with previous works of pressurized
treatment was then calculated and the results were expressed as fruits juices (Buzrul, Hami, Largeteau, Demazeau, 2008;
N/mm. Valdramidis et al., 2009). Yeasts are generally relatively sensitive
to pressure, and HHP has been used successfully to extend the
2.3.8. Determination of polysaccharides shelf life of acidic products whose spoilage microflora are
Polysaccharides content was estimated by a colorimetric primarily yeasts, like fruit sauces, juices and purees (Patterson,
analysis according to the methodology of Miranda et al. (2010). Linton, Doona, 2007). High-pressure inactivation is thought to
One gram of A. vera gel was extracted with 80 mL of water in bath be the result of a combination of morphological changes in
at 100 °C for 2 h, with constant agitation and the samples were microbial cells, such as membrane perturbation and loss of its
vacuum-filtered. The filtrate was diluted to 100 mL in a beaker. function, compression of gas vacuoles, cell lengthening, formation
Two milliliters of the solution and 10 mL of absolute ethanol were of pores in the cell wall, and the destruction of ribosomes
added in plastic tubes; samples were centrifuged at 2500 × g for (Hartmann, Mathmann, Delgado, 2006; Lavinas, Miguel, Lopes,
30 min, and the supernatant was removed; the precipitate was Valente Mesquit, 2008).
dissolved in a final volume of 50 mL water. One milliliter of the When adjusting the experimental microbial data to the modified
filtered solution, 1 mL of phenol at 5 g/100 mL, and 5 mL of Gompertz equation, the following kinetic parameter estimations for the
concentrated sulphuric acid were added to the tops of the tubes. It maximum specific growth rate (μmax), lag-phase(λ) and the shelf life
was allowed to settle for 30 min. Sample absorbance was (SL) for the aerobic mesophilic microorganisms and yeasts counts of
determined at 490 nm (Spectronic® 20 Genesys™, IL, USA). Total A. vera gel samples were obtained. For AMM: SL = 26.13 days,
polysaccharide content was estimated by comparison with a μmax = 0.13 days− 1 and λ = 14.49 days; and for yeasts: SL = 26.19 days,
standard curve generated from d-+-glucose analysis. All solvents μmax = 0.12 days− 1 and λ = 13.15 days. Therefore, for 300 MPa− 1 min,
and reagents were purchased from Sigma (Sigma Chemical Co., St. the modified Gompertz equation was able to describe microbial AMM
Louis, MO, USA). (R2 = 0.95) and Y growth (R2 = 0.95).
The microbial shelf life estimated for pressure-treated 300 MPa/1 -
2.3.9. Color measurement (ΔE) min A. vera gel stored at 4 °C was 26 days for both AMM and Y. In
A. vera gel color was measured by a colorimeter (HunterLab, general, the tendency in pressure-treated products at higher pressure
MiniScan™ XE Plus, Reston, VA, USA). Color was expressed in CIE L* and/or holding time treatments is to produce a significant increase in
(whiteness or brightness), a* (redness/greenness) and b* (yellow- the lag phase times of mesophilic aerobic microorganisms. This may
ness/blueness) coordinates, standard illuminant D65 and observer 10°. be due to a greater severity of cellular damage, as well as the
Five replicate measurements were performed and results were increment of injured bacteria (Briones et al., 2010). As a food
4. 60 A. Vega-Gálvez et al. / Innovative Food Science and Emerging Technologies 13 (2012) 57–63
A DPPH Polyphenolics
fresh Eq (1) treated 40 120.00
C
IC50, Concentration
Polyphenolics (mg
8 35 a
100.00
30
GA/ g d.m.)
(ug mL-1)
25 80.00
7
20 60.00
c
6 15 bc 40.00
10 B
b 20.00
5 5 A A
Log UFC/mL
0 0.00
Untreated 300 400 500
4 Pressure (MPa)
3 Fig. 2. Effect of pressure (5 min) on DPPH-radical scavenging activity and total phenolics
content of A. vera gel after 60 days storage at 4 °C. Values are mean ± standard deviation
(n= 3). Identical letters above the bars indicate no significant difference (P b 0.05).
2
1
the samples treated at 300 and 500 MPa. Moreover, the highest
antioxidant capacity, between pressurized samples was observed at
0
0 10 20 30 40 50 60 70 500 MPa. The effect of pressure on antioxidant capacity is not the same
Storage time (days) among the food products. It has been reported that in tomato puree,
DPPH was not changed by a HP treatment of 400 MPa/25 °C/15 min.
B 9
However, during storage at 4 °C, total antioxidant capacity of pressur-
ized (500 and 800 MPa/20 °C/5 min) orange juice was slightly de-
8 creased by approximately 15% after 21 days (Oey, Van der Plancken, Van
Loey, Hendrickx, 2007).
7 Regarding TPC, they appeared to be sensible to the effect of
processing. Levels of TPC of treated A. vera gel at 400 MPa (26.6 mg
6 GA/100 d.m.) decreased significantly (71%, P b 0.05) as compared to
Log UFC/mL
unprocessed samples (96.81 ± 14.76 mg GA/100 d.m.). TPC did not
5
present significant differences among pressurized samples (300–
4
500 MPa). Previously, the effect of HHP on TPC has been investigated
with varied conclusions. Increase of TPC due to high hydrostatic
3 pressure was reported by other authors working with strawberry and
blackberry purées (Patras, Brunton, Da Pieve, Butler, 2009); olives
2 (Tokuşoğlu, Alpas, Bozoğlu, 2009); apple puree (Landl, Abadias,
Sárraga, Viñas, Picouet, 2010) and vegetables (McInerney, Seccafien,
1 Cynthia, Stewart, Bird, 2007). Others reported that total phenol
content of fruit smoothies was fully degraded by day 30 of storage
0
0 10 20 30 40 50 60 70 suggesting that decrease in dissolved oxygen levels may limit total
Storage time (days) degradation of this type of antioxidant (Keenan et al., 2010).
Based on our results working at 500 MPa/5 min will lead into a
Fig. 1. Effect of pressure (300 MPa/1 min) on: A) aerobic mesophilic microorganisms product with high antioxidant capacity compared to the other
and B) yeasts of A. vera gel. Moulds were not detected. treatments. However, since effect of pressure on DPPH and TPC is
not the same among the food products, further studies are needed to
preservation method, the effectiveness of HHP in destroying micro- preserve the nutritional quality of different gels.
organisms depends on a number of factors that must be taken into
account when optimizing pressure treatments for particular foods 3.3. Vitamin C and E content
(Patterson et al., 2007). The factors are classified into three groups:
process parameters, microbial characteristics and product parameters Fig. 3 shows the effect of process pressure on vitamin E and
(Mañas Pagán, 2005). vitamin C after 60 days of storage. The initial contents of vitamin E and
Based on previous microbiological results, the analysis of quality C were 0.21 mg/100 g d.m. and 127.59 mg/100 g d.m., respectively.
attributes was focused on the effects of HHP (300, 400 and 500 MPA) Vitamin E acts as an antioxidant at the cell membrane level, protecting
during 5 min of processing. the fatty acids of the membranes against damage caused by free
radicals (Repo-Carrasco, Espinoza, Jacobsen, 2003). Vitamin C is
3.2. Effect on antioxidant capacity and total polyphenolics content very susceptible to oxidation under certain environmental conditions
like heat, aw, presence of oxygen, heavy metal ions and alkaline pH
The antioxidant capacity of the gel subjected to high pressure degrading their biological activity. Hence, vitamin C exhibited
treatments (300, 400 and 500 MPa/5 min) was investigated based on significant degradation when subjected to HHP treatment in a
DPPH-radical scavenging activity and total polyphenolics content. multivitamin system. This compound could be affected by chemical
Fig. 2 presents the profiles of radical scavenging activity together with and enzymatic reactions occurring in food samples that may be
total polyphenolics content as function of process pressure (P b 0.05). enhanced by pressure (Valdramidis et al., 2009). In this investigation
Initial contents of DPPH and TPC were 37392.95 ± 2822.05 μg/mL and vitamin C was affected by different pressurization treatments
161.67 ± 49.14 mg GA/100 d.m., respectively. (P b 0.05). The retention of vitamin C after storage for 2 months at
A significant decrease in antioxidant activity was noted in all 4 °C was 60% at 300 MPa, 93% at 400 MPa and 81% at 500 MPa. Oxygen
pressurized gel samples compared to the control sample. The plays an important role in vitamin C degradation both at atmospheric
treatment at 400 MPa showed the maximum reduction compared to pressure and at elevated pressure. Vitamin C pressure stability could
5. A. Vega-Gálvez et al. / Innovative Food Science and Emerging Technologies 13 (2012) 57–63 61
Vitamin E Vitamin C Polysacharides Firmness
Polysacharides (mg/100
160 0.7 7000 10
B 9
Firmness (N/mm)
A AC 6000 B
140 C 8
Vitamin C (mg/100 g d.m.)
Vitamin E (mg/100 g d.m.)
0.6 A
5000 7
A
g d.m.)
120 6
0.5 4000
d 5
100 B c 3000 a
b 4
0.4 c
2000 3
80 a 2
b 0.3 1000 1
60 0 0
Untreated 300 400 500
0.2
40 Pressure (MPa)
d
20 0.1
Fig. 4. Effect of pressure (5 min) on polysaccharides and firmness of A. vera gel after 60-
0 0.0 days storage at 4 °C. Values are mean ± standard deviation (n = 3). Identical letters
untreated 300 400 500 above the bars indicate no significant difference (P b 0.05).
Pressure (MPa)
Fig. 3. Effect of pressure (5 min) on vitamin C and E of A. vera gel after 60 days storage at by-product of soybean (Mateos-Aparicio, Mateos-Peinado, Rupérez,
4 °C. Values are mean ± standard deviation (n = 3). Identical letters above the bars
2011).
indicate no significant difference (P b 0.05).
Fig. 4 also shows the effects of pressure on A. vera gel firmness
(Pb 0.05). Samples pressurized at 300 and 500 MPa showed the same
be explained by differences in molar ratio between ascorbic acid and final firmness of the samples. On the other hand, working at 400 MPa
the initial oxygen content and possible existence of other anti or pro- showed similar firmness when compared to fresh samples. Firmness,
oxidants (Oey, Van Loey, Hendrickx, 2008). which is a measure of the sample texture, can be related to modifications
Evolution of vitamin C content in pressure treated food products in cell structure because of processing. Due to cell disruption, high
has been previously followed. Polydera, Stoforos, and Taoukis (2005) pressure processing facilitates the occurrence of enzymatic and non-
reported 84% retention of vitamin C in orange juice after one month of enzymatic reactions. Substrates, ions and enzymes (PME) which are
storage of samples treated at 600 MPa/4 min. Patras et al. (2009) located in different compartments in the cells can be liberated and
reported that levels of ascorbic acid in strawberry puree treated at 400 interact with each other during HHP treatment. The degree of cell
and 500 MPa were significantly lower than in fresh samples. disruption is not only dependent on the applied pressure level but also
Ascorbate retention of untreated and pressurized (400 MPa, 30 min, on the type of plant cell (Oey et al., 2008). In addition, textural changes
20 °C) strawberry coulis decreases during storage at 4 °C. Initial during A. vera gel pressurization could be due to the enzymatic
content was reduced to 29.38 mg/100 g (88.68%) after ultra-high demethylation of pectins, followed by the formation of calcium pectate
hydrostatic pressure treatment. After 28 days of storage, it was complexes that diffuse to the cell wall/middle lamella facilitating
26 mg/100 g (78.48%) for untreated strawberry coulis and interactions that lead to improved product texture already observed in
22.8 mg/100 g (68.82%) for pressurized coulis (Sancho et al., 1999). pineapple juice (Perera et al., 2010); green beans (Krebbers, Matser,
Barba et al. (in press) reported that pressurization at 400 and 600 MPa Koets, Van den Berg, 2002) and carrots (Trejo Araya et al., 2007). Thus,
for 5–15 min preserved 92% of the ascorbic acid in the blueberry juice based on results, working at 500 MPa/5 min will produce a gel with high
samples. Other authors found no remarkable effects due to the polysaccharides content that cements the cells together resulting in an
treatment on vitamin C content of carrots, tomatoes and broccoli after increase of the firmness sample (Adams, 2000).
pressurization at 600 MPa (Butz et al., 2002).
In literature, information about HHP effect on stability of fat 3.5. Effect on color
soluble vitamins is less abundant than that on water soluble vitamins
(Oey et al., 2007). From Fig. 3, it can be observed that 400 MPa/5 min For color “sensory” evaluation, ΔE is very important quantity
improved the content of vitamin E compared to the untreated sample. determining (Chen, 2008). Depending on the value of ΔE, the color
This enhancement could be due to tocopherols scavenge lipid peroxy difference between the treated and untreated samples can be
radicals and yield a tocopheroxyl radical that can be recycled back to estimated as not noticeable (0–0.5), slightly noticeable (0.5–1.5),
the corresponding tocopherol by reacting with ascorbate or other noticeable (1.5–3.0), well visible (3.0–6.0) and great (6.0–12.0).
antioxidants through different chemical reactions (Sattler, Gilliland, The effect of pressure on A. vera gel color after 60 days storage
Magallanes-Lundback, Pollard, DellaPenna, 2004). In addition, reported the following ΔE values: 13.045 at 300 MPa, 23.3 at 400 MPa
depending on the food matrix, a significant amount of vitamin E and 5.5 at 500 MPa (P b 0.05). From 300 to 400 MPa an increased of
linked to proteins or phospholipids could be released by processing. color is reported; however, when pressure is increased to 500 MPa, a
Thus, a higher content of this vitamin can be obtained compared to the notable reduction on ΔE is observed reaching values between 3 and 6
non-processed sample (Casal, Amara, Oliveira, 2006). which according to Chen (2008) are appreciable differences. Further-
more, the ΔE of the sample without pressure treatment showed a
3.4. Effect on polysaccharides and firmness value of 9.105 ± 3.13 representing a large color difference according
to Chen (2008). Some authors have reported that high pressure
Polysaccharides account for most of the dry matter of the A. vera treatment (at low and moderate temperatures) has a limited effect on
parenchyma (Femenia et al., 2003). A. vera gel presented an initial pigments (e.g. chlorophyll, carotenoids, anthocyanins, etc.) responsi-
content of polysaccharides of 6155.96 ± 24.71 mg/100 g d.m. Fig. 4 ble for the color of fruits and vegetables. Nevertheless, the color
shows the effects of pressure on the polysaccharides of the sample compounds of high pressure processed fruits and vegetables can
(P b 0.05). All treatments decreased the initial polysaccharides gel change during storage due to incomplete inactivation of enzymes and
content. However, between pressurized samples, an increased in microorganisms, which can result in undesired chemical reactions
process pressure presented an increase in polysaccharides values. In (both enzymatic and non-enzymatic) in the food matrix (Barba et al.,
fact, the treatment at 500 MPa presented the highest increase. These in press; Oey et al., 2008; Perera et al., 2010). These results indicate
results were in agreement with those reported by other authors that final color of gel samples is highly dependent on the operation
working with fruits (Yang, Jiang, Wang, Zhao, Sun, 2009) and with a pressure.
6. 62 A. Vega-Gálvez et al. / Innovative Food Science and Emerging Technologies 13 (2012) 57–63
4. Conclusions Lavinas, F. C., Miguel, M. A., Lopes, M. L., Valente Mesquit, Y. L. (2008). Effect of high
hydrostatic pressure on cashew apple (Anacardium occidentale L.) juice preserva-
tion. Journal of Food Science, 73(6), 273–277.
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5 min) on quality attributes as well as microbiological growth were Francis Group, LLC (Chapter 28).
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modified Gompertz equation. The highest antioxidant capacity Mateos-Aparicio, I., Mateos-Peinado, C., Rupérez, P. (2011). High hydrostatic
including DPPH between pressurized samples was observed at pressure improves the functionality of dietary fibre in okara by-product
from soybean. Innovative Food Science and Emerging Technologies, 11,
500 MPa (P b 0.05). Pressurized samples presented similar values of 445–450.
TPC (P b 0.05). All treatments decreased initial vitamin C content being McInerney, J. K., Seccafien, C. A., Cynthia, A. C., Stewart, M., Bird, A. R. (2007). Effects of
the lowest values that at 300 MPa. Vitamin E showed a different trend, high pressure processing on antioxidant activity, and total carotenoid content and
availability, in vegetables. Innovative Food Science and Emerging Technologies, 8,
presenting an increased at 400 MPa/5 min. Among pressurized
543–548.
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polysaccharides values being the highest values those reported at temperature on the drying kinetics, physicochemical properties, and antioxidant
500 MPa/5 min. Since polysaccharides contribute to food texture, HHP capacity of aloe vera (Aloe barbadensis Miller) gel. Journal of Food Engineering, 91,
297–304.
also had significant effect on the firmness of the sample. Modifications Miranda, M., Vega-Gálvez, A., López, J., Parada, G., Sanders, M., Aranda, M., et al. (2010).
in texture could be related to changes in cell structure because of Impact of air-drying temperature on nutritional properties, total phenolic content
processing (P b 0.05). Regarding to samples color, working at and antioxidant capacity of quinoa seeds (Chenopodium quinoa Willd.). Industrial
Crops and Products, 32, 258–263.
500 MPa/5 min presented the lower ΔE value (P b 0.05). Based on Oey, I., Van der Plancken, I., Van Loey, A., Hendrickx, M. (2007). Does high pressure
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Acknowledgments
content and colour of strawberry and blackberry purées. Innovative Food Science
and Emerging Technologies, 10, 308–313.
The authors gratefully acknowledge the financial support for Patterson, M., Linton, M., Doona, C. (2007). Introduction to high pressure processing
foods. In C. Doona, F. Feeherry (Eds.), High Pressure Processing of Foods (pp. 7). :
project FONDECYT 1090228 and Research Department of Universidad
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