Flávio Luis Schmidt

Transmission of Chagas Disease (American Trypanosomiasis) by Food

In April 2009, the centenary of the discovery of the American trypanosomiasis, or Chagas disease, was celebrated. A hundred years after the discovery, little has been invested in diagnostics and treatment because the disease affects mainly poor people in developing countries. However, some changes in the epidemiology of the disease are of great importance today. Chagas disease transmitted through food is a public health concern in all areas where there is a reservoir of Trypanosoma cruzi in wild animals (e.g., mammals and marsupials) and/or where infected triatomine bugs are in contact with human food source items (especially fruits and vegetables). Recently, several outbreaks of illness related to the ingestion of food contaminated with T. cruzi have been recorded in Brazil, Colombia, and Venezuela.

Atividades das enzimas peroxidase (POD) e polifenoloxidase (PPO) nas uvas das cultivares benitaka e rubi e em seus sucos e geléias

Peroxidase (POD) and polyphenoloxidase (PPO) are oxidative enzymes related to the darkening process suffered by fruits. Thus, the control of the effects of these enzymes, in the preservation of fruit, in order to minimize the darkening process is considered of great importance for food processing technology. The present study investigated the effects of POD and PPO on fresh grapes from Benitaka and Rubi cultivars, as well as the thermal stability and the residual enzymatic activities in the processing of juice and jelly (extra and light). Moreover, the microbiological quality of the processed products was evaluated. It was observed that, the effect of the POD enzyme, from the soluble fraction, as well as from the ionically bound fraction, was similar in both varieties of grapes, Benitaka and Rubi. But the effect of the PPO enzyme was higher in the Rubi variety. Operations such as cooking and pasteurizing were the most efficient processes to reduce the residual enzymatic effect of POD and PPO in grape jelly, in comparison to the juice. Although such processes were not enough for total enzymatic inactivation, they permitted a considerable reduction, thus were efficient to guarantee the microbiological safety of the products, such as jelly and juice.

Survival In Vitro and Virulence of Trypanosoma cruzi in Acai Pulp in Experimental Acute Chagas Disease

Chagas disease is a parasitic infection with high socioeconomic impact throughout Latin America. Although this severe, incurable disease can be transmitted by several routes, oral transmission is currently the most important route in the Amazon Basin. Açaí pulp has nutritional properties and is popular throughout Brazil and abroad. However, this pulp has been associated with microepidemics of acute Chagas disease (ACD) in northern Brazil, where açaí fruit is the main food supplement. In this study, we examined the in vitro survival and in vivo virulence of Trypanosoma cruzi Y strain in açaí pulp. Aliquots of in natura açaí pulp produced in Belém city in the northern Brazilian state of Pará were mixed with 10⁵ trypomastigotes. The samples were incubated at room temperature or at 4 or -20°C for various periods, and the parasites were isolated by forced sieving. The resulting eluates were examined by microscopy, and the trypomastigotes were administered intraperitoneally, orally, or by gavage to immunodeficient mice (C.B-17-Prkdc(scid)/PasUnib) that had been pretreated with antibiotics. Parasitemia was quantified by the Brener method, and mortality was recorded daily. All routes of administration resulted in ACD. A 5-day delay in the onset of parasitemia occurred with oral administration. The survival and virulence of the parasites were unaffected by prior incubation at room temperature for 24 h, at 4°C for 144 h, and at -20°C for 26 h. These results indicate that T. cruzi can survive and retain its virulence in açaí pulp under various conditions and that cooling and freezing are not suitable methods for preventing foodborne ACD.

Virulence of Trypanosoma cruzi in Açai (Euterpe oleraceae Martius) Pulp following Mild Heat Treatment

Outbreaks of acute Chagas disease (ACD) in northern Brazil can be caused by the ingestion of unprocessed açai pulp contaminated with Trypanosoma cruzi . The aim of this study was to determine the minimum thermal process required to inactivate T. cruzi in açai pulp. Trypomastigotes (100,000) of T. cruzi Y strain were added to 0.15 M NaCl or açai pulp and continuously mixed while being heat treated at 37 to 49°C for up to 1 h. When necessary, parasites were separated from açai pulp by forced sieving. Inocula were administrated intraperitoneally in inbred immunodeficient C.B-17-Prkdcscid/Pas Unib mice, and the recipients were monitored for parasitemia and mortality. Mice received prophylactic antibiotic therapy by using cephalexin to prevent bacterial infection from the açai pulp. T. cruzi retained its virulence in 0.15 M NaCl and açai pulp at 44 ± 0.1°C for 10 min and at 43 ± 0.1°C for 20 min, respectively, causing ACD and death in mice up to 24 days after infection. Incubation of açai pulp inoculum above 43°C for 20 min neutralized T. cruzi virulence, thereby preventing ACD and death in murine recipients. The heating of açai pulp above 43°C for 20 min is a practical and effective measure to prevent foodborne ACD caused by T. cruzi .

Rheological Analysis of Sucrose Solution at High Temperatures Using a Microwave-Heated Pressurized Capillary Rheometer

Thermal process design, optimization, and deviation require the knowledge of engineering properties of food, such as rheological behavior, which is highly dependent on temperature. If a process is calculated based on the parameters obtained by extrapolation, it might lead to over- or underprocessing. The long time required for the product to reach the desired temperature, which is usual in many rheometers, may induce unexpected changes on the product. Model solutions are often used in engineering projects in order to simulate characteristics of real products. Thus, the objective of this study was to obtain rheological data of sucrose model solution at the actual high UHT (ultra-high temperature) process temperatures using a pressurized capillary rheometer, heated by a microwave system. The results provide the rheological behavior of the sucrose solutions and show that there is no deviation of the linearity of the Arrhenius plot above 100 °C for this product. This work was useful to illustrate the use of the applied methodology and to validate the newly built microwave-heated capillary rheometer. The data obtained confirm the stability of nonsaturated sucrose solution when treated above 100 °C and presents an important contribution to the literature database, since sucrose solutions are used as models for many table syrups, such as maple and sorghum syrups.

Osmotic dehydration of yellow melon using red grape juice concentrate

The main objectives of this work were to study the effect of fruit ripening on the melon osmotic dehydration at reduced pressure and to model the mass transfer of moisture during melon dehydration with grape juice concentrate and sucrose solution. The ripening level had no relevant effect over the physical characteristics of the final product, with soluble solids, moisture and water activity without significant differences. Besides, the mass loss and solute gain parameters did not show significant differences, and only the solute gain had few variations. The process of the osmotic dehydration with grape juice concentrate was the most effective one, with higher dehydration and lowest solutes gain compared to the process carried out with sucrose solution. The water effective diffusivity calculated by the Fick’s equation for the process conduced with grape juice was lower than the one obtained for the sucrose solution, according to different equilibrium moisture content calculated by Peleg’s equation. The dehydrated melon with grape juice concentrate showed reduced water activity (~ 0.92) and low moisture content (~ 58%).

Kinetics of the acidification of hearts-of-palm (Bactris gasipaes Kunth.).

Summary The diffusion of acid to the inside of vegetables pasteurized and then preserved by acidification should occur in a period of time short enough to inhibit the germination of spores and consequent formation of botulism toxin in ready to eat food. The present study aimed to verify the time necessary to acidify the different tissues that make up the hearts of palm. Significant differences were observed in the time taken to lower the pH of the different tissues. The pH of the external tissue lowered very quickly as compared to the internal parts. The results for acid penetration were similar to those of the diffusion of a coloured solution. The time necessary to lower the pH to safe values in cuts of hearts of palm with a length of 9 cm and diameter of 3 cm was greater than 6 days on the inside of the vegetable. This period is long enough to permit the formation of botulism toxin if spores of Clostridium botulinum are present in the stem.

Chemical and physical characterization of mume fruit collected from different locations and at different maturity stages in São Paulo State.

Prunus mume is widely studied due to its health benefits regarding increase of blood fluidity and consequent improvement of the cardiovascular system and the prevention or even the fight against different types of cancer. However, in Brazil this culture is found only among oriental descendants. The present study aimed to characterize mume fruit collected from three different locations in the State of Sao Paulo regarding general aspects such as pH, total titratable acidity (TTA), total soluble solids (TTS), pectin content and yield of pulp and chemical characteristics: total phenolic compounds (TPC) and antioxidant capacity. Mume fruit were collected unripe and analyzed until maturation about 88 days after flowering. Fruit collected in Botucatu came from a commercial mume fruit producer and had average weight of 16.9 g, while in fruit from other locations weight varied from 5.7-6.9 g. TSS ranged from 9.5 to 10.0 Brix, total solids was 10.2-12.2% and pH showed values between 2.5 and 2.7 for all locations. TTA expressed in citric acid decreased from 4.0-5.7 g (100g - 1) at unripe stage to 2.0-3.8 g (100g - 1) in mature-stage fruit. Pectin content decreased from 11.2 to 10.8% during fruit maturation, TPC content was 147-226 mg catechin (g - 1) on a dry matter basis and the antioxidant capacity was 96-169 µMol Trolox (g - 1) on a dry matter basis or 21-34 µMol Trolox (g - 1) on a wet matter basis.