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| Author(s): |
Ana Laura Tiberio de Jesus
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos |
| Defense date: | 2017-12-01 |
| Examining board members: |
Marcelo Cristianini;
Adriano Gomes da Cruz;
Dirce Yorika Kabuki;
Karen Signori Pereira;
Ruann Janser Soares de Castro
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| Advisor: | Marcelo Cristianini |
| Abstract | |
Açaí (Euterpe oleracea Mart.) is a highly perishable fruit which needs treatments that prolong its shelf life, inactivating enzymes naturally present and spoilage and pathogenic microorganisms. Food processing using an emerging non-thermal technology (high pressure) could be an alternative to conventional pasteurization processes for thermosensitive products, by the advantages of minimizing sensorial and nutritional losses. In this context, this study aimed to evaluate the effect of high isostatic pressure technology (HIP) on the inactivation of the main enzymes present in açaí pulp (polyphenol oxidase and peroxidase), as well as inactivation of a spoilage microorganism (Lactobacillus fructivorans), a strain of Escherichia coli and a sporulated microorganism (Alicyclobacillus acidoterrestris), allowing to establish adequate process parameters to ensure the microbiological safety of the product and preserve the functional and sensory properties of fruit. Pressures of 400, 500 and 600 MPa, times of 5 and 15 minutes and temperatures of 25 and 65°C were used. The analyzes were: enzymatic activity, color, microbiological, sensorial, anthocyanins, total phenolic compounds, antioxidant activity and rheological. The results showed that peroxidase enzyme is heat resistant and baroresistente in açaí pulp under the conditions studied, in opposition, polyphenoloxidase, which presented greater inactivation (71.7%) in the condition of 600 MPa / 15 min / 65 ° C. The HIP process was compared to a conventional thermal process (85 °C/1min), where partial inactivation of the two enzymes was observed, but with a change in the color (?E = 4.22) visible to the human eye. For Escherichia coli, the HIP allowed the inactivation of 6.1 log cycles in all conditions studied. For Alicyclobacillus acidoterrestris, a treatment at 600 MPa/65°C (5, 10, 15, 20 and 25 min) was determined resulting in a value of 4 decimal reductions of 13.5 min. Two better conditions were selected, 600 MPa/5 min/25 °C and 600 MPa/5 min/65 °C and together with the control and pasteurized samples, were evaluated during storage at 5 °C. For the group of microorganisms (mesophilic aerobes, psychotrophic aerobes and lactic acid bacteria), it was found that after processing by HIP (600 MPa / 5min / 65°C) the counts remained below 2 log CFU/mL during 28 days. No presence of Salmonella sp was detected in any sample, which indicates that the product remained in accordance with current legal standards. For both, the API and pasteurized samples, the microorganism count values remained below the maximum allowable limit required by the legislation for 28 days. The results of the sensory analysis showed that API process influenced the texture perception of açaí samples (more consistent texture) and during rheological analysis it was observed that samples processed by HIP showed an increase in viscosity. In pressurized açaí pulps, the extraction of anthocyanins increased 37%, compared to control sample, for both HIP processes. In contrast, the heat treatment reduced the pigment content by 16.3% compared to the in natura sample. For total phenolics, both processes at 600 MPa at 25°C and 65°C when compared to the in natura sample, increased the extraction by 11.44% and 10.25%, respectively. The API was also able to maintain the antioxidant activity for the pulps processed at 600 MPa for 5 min at 25 and 65 ° C. In view of the results, it was concluded that the HIP processing was shown as an alternative for thermal treatments of pasteurization, generating a safe microbiological product, with preservation of its nutritional and sensorial characteristics (AU) | |
| FAPESP's process: | 15/01570-0 - Açaí pulp (Euterpe oleracea Martius) processing by high isostatic pressure |
| Grantee: | Ana Laura Tibério de Jesus |
| Support Opportunities: | Scholarships in Brazil - Doctorate |