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*Corresponding to the average of five replicates. Table 1 Chemico-physical and microbiological characteristics of pesto sauce

Table 1 *Corresponding to the average of five replicates. Table 1 Chemico-physical and microbiological characteristics of pesto sauce

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Figure 1 Single dose package with gas fluxes considered in the model : N = CO, flux in the sauce; P = permeation fluxes through the film; UfV = unfilled volume; z = CO, flux coordinate. The gas permeability of packaging films was
Figure 1 Single dose package with gas fluxes considered in the model : N = CO, flux in the sauce; P = permeation fluxes through the film; UfV = unfilled volume; z = CO, flux coordinate. The gas permeability of packaging films was
Abbreviation for films: CPP: cast polypropylene EVOH: ethylene vinyl alcohol OPA: orientated polyamide CPA: cast polyamide OPP: orientated polypropylene LDPE: low density polyethylene Table 2 Characteristics of multifilm packaging materials
Abbreviation for films: CPP: cast polypropylene EVOH: ethylene vinyl alcohol OPA: orientated polyamide CPA: cast polyamide OPP: orientated polypropylene LDPE: low density polyethylene Table 2 Characteristics of multifilm packaging materials
Figure 2 Flow diagram of the iterative simulation for predicting product shelf-life (C,,, = CO, concentration inside the package (mol cm™*); C,, = CO, concentration inside the package at steady-state (mol cm™); N,,, = total microbial count in the sauce (c.f.u. g7'); Nun. = total microbial count allowable in the sauce = 10° (c.f-u. g7'); Tm = shelf-life (day).
Figure 2 Flow diagram of the iterative simulation for predicting product shelf-life (C,,, = CO, concentration inside the package (mol cm™*); C,, = CO, concentration inside the package at steady-state (mol cm™); N,,, = total microbial count in the sauce (c.f.u. g7'); Nun. = total microbial count allowable in the sauce = 10° (c.f-u. g7'); Tm = shelf-life (day).
Figure 3 Oxygen uptake versus time, corresponding to different starting total microbial concentrations in the sauce. HO, 2300 c.f.u. g'; O, 50000 cfu. go!
Figure 3 Oxygen uptake versus time, corresponding to different starting total microbial concentrations in the sauce. HO, 2300 c.f.u. g'; O, 50000 cfu. go!
Figure 4 Anaerobic carbon dioxide production versus time, corresponding to different starting total microbial concentrations in the sauce. LH, 2300 c.f.u. g-'; O, 50 000 cfu. gt. It can be observed in Table | that the fresh product is characterized by a low value of total organism counts with a predominance of Lactobacillus spp. in comparison with mould and yeast.
Figure 4 Anaerobic carbon dioxide production versus time, corresponding to different starting total microbial concentrations in the sauce. LH, 2300 c.f.u. g-'; O, 50 000 cfu. gt. It can be observed in Table | that the fresh product is characterized by a low value of total organism counts with a predominance of Lactobacillus spp. in comparison with mould and yeast.
earliest time of storage, as shown in Fig. 5. On the contrary, in an atmosphere of nitrogen, the growth of moulds was found not to be signifi- cantly (P > 0.05) affected compared to growth in air during a lag period lasting about 10 days. The predominantly Gram-positive facultatively anaerobic microflora dominated by Lactobacillus spp. is beneficial, as the lactobacilli metabolism by-products are usually produced very slowly and are inoffensive (Farber, 1991). Moreover the envi- ronment, owing to low pH _ values, is not favourable to the growth of many pathogens (Prince & Lee, 1970).
earliest time of storage, as shown in Fig. 5. On the contrary, in an atmosphere of nitrogen, the growth of moulds was found not to be signifi- cantly (P > 0.05) affected compared to growth in air during a lag period lasting about 10 days. The predominantly Gram-positive facultatively anaerobic microflora dominated by Lactobacillus spp. is beneficial, as the lactobacilli metabolism by-products are usually produced very slowly and are inoffensive (Farber, 1991). Moreover the envi- ronment, owing to low pH _ values, is not favourable to the growth of many pathogens (Prince & Lee, 1970).
Figure 5 Moulds (c.f-u. g~') in pesto sauce in various atmospheres and stored at 5°C, package type a. Moreover, the inhibiting effect of carbon diox- ide on fungi was very marked (P < 0.01) from the International Journal of Food Science and Technology 2000, 35, 293-303
Figure 5 Moulds (c.f-u. g~') in pesto sauce in various atmospheres and stored at 5°C, package type a. Moreover, the inhibiting effect of carbon diox- ide on fungi was very marked (P < 0.01) from the International Journal of Food Science and Technology 2000, 35, 293-303
Figure 6 Total microbial count (c.f.u. g™') of pesto sauce in various atmospheres and stored at 5°C for 130 days, package type a. As shown in Fig. 6 the growth rate, p, decreased in relation to increasing partial carbon dioxide pressure during the logarithmic period. This effect is related to a sharp increase in bacte- rial lag phase and is enhanced further by lower- ing the temperature (Olson ef al., 1980). An added factor is increased solubility of CO, at lower temperatures. The storage life of MAP pre- pared vegetables is terminated when microbial growth reaches 10’-10* organism per gram (O’Beirne, 1990). When using the type a package, the control sauce packaged in air approached the value of 10° c.f.u. g', chosen as a conservative limit, after 40 days, while the sauce packaged in modified atmosphere (10% CO, and 90% N,;) reached the same value after 120 days. Therefore the shelf-life limit was reached at these times. On the other hand, the growth inhibition by carbon
Figure 6 Total microbial count (c.f.u. g™') of pesto sauce in various atmospheres and stored at 5°C for 130 days, package type a. As shown in Fig. 6 the growth rate, p, decreased in relation to increasing partial carbon dioxide pressure during the logarithmic period. This effect is related to a sharp increase in bacte- rial lag phase and is enhanced further by lower- ing the temperature (Olson ef al., 1980). An added factor is increased solubility of CO, at lower temperatures. The storage life of MAP pre- pared vegetables is terminated when microbial growth reaches 10’-10* organism per gram (O’Beirne, 1990). When using the type a package, the control sauce packaged in air approached the value of 10° c.f.u. g', chosen as a conservative limit, after 40 days, while the sauce packaged in modified atmosphere (10% CO, and 90% N,;) reached the same value after 120 days. Therefore the shelf-life limit was reached at these times. On the other hand, the growth inhibition by carbon
Figure 7 Total microbial count (c.f.u. g~') of pesto sauce in various atmospheres and stored at 20°C for 8 days, package type a. dioxide decreased markedly with increasing tem- perature, as shown in Fig. 7. The limit value was reached at 20°C storage temperature after 2 days and 4 days, respectively, for control air package and MAP (10% CO, and 90% N,). These results underline the importance of good temperature control in the chill chain, even if a modified atmosphere is adopted.
Figure 7 Total microbial count (c.f.u. g~') of pesto sauce in various atmospheres and stored at 20°C for 8 days, package type a. dioxide decreased markedly with increasing tem- perature, as shown in Fig. 7. The limit value was reached at 20°C storage temperature after 2 days and 4 days, respectively, for control air package and MAP (10% CO, and 90% N,). These results underline the importance of good temperature control in the chill chain, even if a modified atmosphere is adopted.
Comparison of experimental and calculated shelf-life values showed that the model underesti- mates real shelf-life with an error range of 4%, if package a is concerned, and 7% if package b is concerned. Having found calculated values higher than experimental ones, the proposed approach is to be considered conservative. The selected type a package was simulated to allow attainment of an equilibrium atmosphere corresponding to 10% CO, and 90% N,. The maximum deviation between experimental and calculated data with this package was found to be 4%, a value which may be con- sidered acceptable for practical application. International Journal of Food Science and Technology 2000, 35, 293-303
Comparison of experimental and calculated shelf-life values showed that the model underesti- mates real shelf-life with an error range of 4%, if package a is concerned, and 7% if package b is concerned. Having found calculated values higher than experimental ones, the proposed approach is to be considered conservative. The selected type a package was simulated to allow attainment of an equilibrium atmosphere corresponding to 10% CO, and 90% N,. The maximum deviation between experimental and calculated data with this package was found to be 4%, a value which may be con- sidered acceptable for practical application. International Journal of Food Science and Technology 2000, 35, 293-303
‘Mean of 10 observations with 1 = poor and 9 = excellent. **Mean scores within a column followed by different letters are significantly (P < 0.01) different. The modified atmosphere and some packaging materials proved beneficial in preserving quality and extending the shelf-life of pesto sauce, main- taining excellent organoleptic appearance and colour. The mathematical model that was devel- oped appears satisfactory in predicting equilibra- tion time as well as equilibrium gas composition
‘Mean of 10 observations with 1 = poor and 9 = excellent. **Mean scores within a column followed by different letters are significantly (P < 0.01) different. The modified atmosphere and some packaging materials proved beneficial in preserving quality and extending the shelf-life of pesto sauce, main- taining excellent organoleptic appearance and colour. The mathematical model that was devel- oped appears satisfactory in predicting equilibra- tion time as well as equilibrium gas composition
while it was indicated that with a carbon dioxide concentration of 20% (v/v), it was least liked dur- ing the first 10 days of storage. Sensory evalua- tion showed that the shelf-life of pesto sauce stored in a modified atmosphere is acceptable for up to 120 days’ refrigerated storage, with signifi- cant (P < 0.01) final hedonic scores as follows: colour: 7.1; odour: 6.1; taste: 6.5; overall accept- ability: 6.9. Even if the results of this research show that the optimal atmosphere corresponds to 90% N,, 10% CO, at steady-state, further experi- ments should be used to investigate different atmospheres, e.g. 85% N, and 15% CO,, which could still prove better than those investigated. The colour and odour of pesto, due mainly to the presence of basil, are typical parameters for consumer acceptability and for this reason they were selected as primary attributes in sensory evaluations. The responses were not only in visu- al appearance but also in the taste of the sauce, and are summarized in Tables 5 and 6. The scores for fresh sauce were as follows: odour: 8.5; colour: 7.9; taste: 7.3; overall acceptability: 7.7. The panel taste scores showed a markedly decreased liking (P < 0.01) for the colour attribute after 5 days in the control and 10 days for sauce packed in nitrogen. This can be attrib- uted to combined enzymatic and non-enzymatic browning of the sauce: phenol compounds pre- sent in basil are enzymically oxidized first to orthoquinones and then to coloured polymers, while oxidation of lipids and the subsequent reac- tion of oxidized compounds with amino acids cause non-enzymatic browning. The pesto sauce in atmosphere with CO, not exceeding 10% scored the highest acceptability with 7 of 10 taste panelists indicating no appreciable difference with the control within 40 days of refrigerated storage,
while it was indicated that with a carbon dioxide concentration of 20% (v/v), it was least liked dur- ing the first 10 days of storage. Sensory evalua- tion showed that the shelf-life of pesto sauce stored in a modified atmosphere is acceptable for up to 120 days’ refrigerated storage, with signifi- cant (P < 0.01) final hedonic scores as follows: colour: 7.1; odour: 6.1; taste: 6.5; overall accept- ability: 6.9. Even if the results of this research show that the optimal atmosphere corresponds to 90% N,, 10% CO, at steady-state, further experi- ments should be used to investigate different atmospheres, e.g. 85% N, and 15% CO,, which could still prove better than those investigated. The colour and odour of pesto, due mainly to the presence of basil, are typical parameters for consumer acceptability and for this reason they were selected as primary attributes in sensory evaluations. The responses were not only in visu- al appearance but also in the taste of the sauce, and are summarized in Tables 5 and 6. The scores for fresh sauce were as follows: odour: 8.5; colour: 7.9; taste: 7.3; overall acceptability: 7.7. The panel taste scores showed a markedly decreased liking (P < 0.01) for the colour attribute after 5 days in the control and 10 days for sauce packed in nitrogen. This can be attrib- uted to combined enzymatic and non-enzymatic browning of the sauce: phenol compounds pre- sent in basil are enzymically oxidized first to orthoquinones and then to coloured polymers, while oxidation of lipids and the subsequent reac- tion of oxidized compounds with amino acids cause non-enzymatic browning. The pesto sauce in atmosphere with CO, not exceeding 10% scored the highest acceptability with 7 of 10 taste panelists indicating no appreciable difference with the control within 40 days of refrigerated storage,
Related topics:
Sensory EvaluationSensory AnalysisModified atmosphere packaging
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