[Shelf-life and sensorial evaluation of corn tortillas, made with preservatives and texture conditioners]. / Vida de anaquel y evaluación sensorial en tortillas de maíz elaboradas con conservadores y mejoradores.

With the objective of producing packaged tortillas with a longer shelf-life which, at the same time, have the qualities of fresh tortillas, the effects of preservatives and texture conditioners on rheologic and sensory characteristics and shelf-life of tortillas made with nixtamalized corn flour were studied. The preservatives evaluated were potassium sorbate (SK) and calcium propionate (PCa). The texture conditioners used were carboxymethylcellulose (CMC) and sodium stearyl-2 lactilate (SS2L). Fresh tortillas were evaluated for pH, yield, texture, elasticity, and sensory quality. The packaged tortillas were packed in polyethylene bags and stored at 4 degrees C. The tortillas with 0.1% SK, 0.1% PCa, and 0.25% SS2L were the most acid (pH = 5.12), had the longest shelf-life (53 days with no microorganism growth), and the lowest total count of aerobic mesophylls (23 colony forming units). The highest yields resulted from the treatment with 0.5% CMC, producing the most elastic tortillas but those with the shortest shelf-life (18 and 24 days). The sensory evaluation, done ten days after packing by five trained panel members, judged that best treatment was that which contained 0.1% SK, 0.1% PCa, and 0.5% CMC. These tortillas were judged to be the softest and most elastic. For the remaining attributes, the best tortillas were those processed by the traditional method (fresh). In the pleasure test, the opinion of the consumers was that the tortilla with the best flavor was the traditionally prepared tortilla. Nevertheless, the treatments with mixtures of preservatives and texture conditioners were graded with scores similar to those obtained by two commercial packaged tortillas.

[Evaluation of the nixtamal-tortilla-making quality of mixtures of corn (Zea mays) and hard beans (Phaseolus vulgaris)]. / Evaluación de la calidad nixtamalera-tortillera de mezclas maíz-frijol endurecido (Zea mays-Phaseolus vulgaris).

In Mexico, some varieties of beans become hard during storage, and required a longer time for cooking. Beans which need more than four hours to cook are deemed unsuitable for human consumption by the government agency CONASUPO even though their nutritional value is unaltered. The objective of this study was to evaluate the nixtamal-tortilla-making quality of mixtures of maize and hard beans, protein, sensory evaluation, and shelf life of the tortillas. The tortillas were made from mixtures of maize with 5% and 10% hard beans without the seed coat and compared with tortillas made with 100% maize. The mixtures and the control were nixtamalized for 20, 30 and 40 minutes with 1% lime (CaO). The maximum viscosity of the mass were statistically equal to that of the control. The mixture with 10% beans, 90% maize, and 30 min of nixtamalization produced tortillas with 26.3% more protein than the control. The texture evaluated in the Instron showed that the tortillas with 10% beans were harder than the control; however, in the sensory evaluation, the recently-made tortillas with 30 min nixtamalization were judged the best, with no significant differences between the control and the mixtures of maize with hard beans. The analysis of fungi, yeasts, and bacteria at room temperature and with refrigeration (4 degrees C), showed that the growth of microorganisms was directly proportional to the percentage of beans added and the duration of storage. The largest number of microorganisms was found at room temperature after 48 h of storage.

Retrospective study of children born to HIV-1-infected mothers in a pediatric hospital in Argentina.

The aim of this retrospective study, which included 103 children born to human immunodeficiency virus type 1 (HIV-1)- infected mothers, is to initiate a database on HIV-infected children, which has to date been unavailable in Argentina. All HIV-1 seropositive children admitted to the Pedro de Elizalde Children's Hospital in Buenos Aires from March 1, 1987, to December 31, 1992, were enrolled in this study. The number of patients enrolled dramatically increased each year during the period of study. Of the 60 infected children, 22 (36.66%) have died with a clinical diagnosis of HIV-1 infection; in 10 of those children HIV infection was also confirmed by P24 antigenemia and/or polymerase chain reaction (PCR): 20 qualified for the Centers for Disease Control and Prevention (CDC) P2D class (P2D1 = 7, P2D2 = 10, P2D3 = 3), 1 for P2C, and 1 for P2A, whose cause of death was pneumonia. The mean age of death was 14.8 months, 18 (82%) died before 18 months. When immunoglobulin G (IgG), IgM, and IgA levels were determined according to age and clinical status, significant differences (P < 0.005) were observed when both asymptomatic and symptomatic infected children (P1, P2) were compared with noninfected children (P3). A significant difference was also obtained between those children who qualified for P2 classification prior to 12 months of age who died early (at or prior to 25 months) and those who reached stage P2 after 12 months of age and have survived to date (X2 = 24.73, p < 0.0001; RR = 5.83, 2.52 < RR < 13.49).

Overt and latent HIV 1 and HTLV-I infection in cohorts of at high risk individuals in Argentina.

We conducted a survey using serology and polymerase chain reaction assays to detect HIV 1 and/or HTLV-I antibodies and viral DNA, respectively, in 113 intravenous drug abusers and in 62 sexually active high risk individuals attending two Drug Addict Centres and a Centre for Venereal Diseases in Buenos Aires, Argentina. At the time of the survey 137 of these subjects were known to be HIV 1 seropositive but none of them was symptomatic. Serological tests for HTLV-I were found to be positive in 38 (21.7%) of the HIV 1 positive individuals, whereas all of the 38 HIV 1 seronegative subjects were also seronegative for HTLV-I antibodies. Gene amplification assays carried out in blood sample DNA from the 38 HIV 1/HTLV-I seronegative individuals, revealed HIV 1 DNA in six out of 28 intravenous drug abusers (21.5%). One subject (2.6%) was positive for both HIV 1 and HTLV-I DNA sequences, whereas four (10.5%) showed HTLV-I DNA only. To determine whether these individuals were infected with HTLV-I and/or HTLV-II, DNA samples were also amplified with HTLV-II specific primers and no evidence of HTLV-II infection was observed. None of the subjects seroconverted according to conventional serological tests during the 2 year follow-up period. The 10 seronegative subjects belonging to the sexual risk group were negative for both HIV 1 and HTLV-I in polymerase chain reaction assays. We conclude that not only HIV 1, but also HTLV-I is a widely spread infection in intravenous drug abusers and sexually active high risk individuals in Argentina.(ABSTRACT TRUNCATED AT 250 WORDS)

[Flour of hard bean (Phaseolus vulgaris) in the preparation of bread]. / Harina de frijol endurecido (Phaseolus vulgaris L.) en la preparación de pan.

In order to utilize hardened beans, we proposed to find the method most indicated for the preparation of bean flour to determine their nutritional value, and to make bread of high industrial, nutritional quality, and good sensory characteristics, using blends of bean and wheat flours. Two types of flour were prepared, testing four soaking temperatures (22, 30, 40 and 50 degrees C) and two methods to remove the testa (under moist and dry conditions). At laboratory level, the dry testa removal method gave the best flour yields (mean = 85.8%) and the highest protein content (mean = 23.7%). Comparison between soaking temperature at 30 and 50 degrees C was not significant (alpha = 0.05). At pilot plant level, with soaking at 50 degrees C the flour yields were 58.0% for moist testa removal (H1) and 74.0% for dry removal (H2), with a protein content of 22.6% for H1 and 23.0% for H2. The H1 and H2 flours were added to wheat flour at 5, 10 and 15% for bread making. The addition of 5.0% gave breads with similar protein content and sensory characteristics to those of the control, wheat. A diet based on bean-flour bread resulted in greater weight gains than that with casein for gold hamsters. The study also demonstrated the importance of heat-treating of the bean flours, because when flour without previous heat treatment was administered, the animals lost weight and died. This effect was overcome by the process of baking the flours at 140 degrees C for four hours.

Harina de frijol endurecido (Phaseolus vulgaris L.) en la preparación de pan / Flour of hard bean (Phaseolus vulgaris) in the bread preparation

Con el propósito de utilizar el frijol endurecido, se propuso la búsqueda del método indicado para obtener harinas de frijol, determinar su valor nutritivo y elaborar panes con mezclas de harina de frijol y trigo de buena calidad industrial, nutricional, y sensorial. Se elaboraron dos tipos de harina, ensayándose cuatro temperaturas de remojo (22, 30, 40 y 50§C) y dos métodos de separación de testa (húmedo y seco). A nivel de laboratorio la separación de testa en seco proporcionó los mejores rendimientos harineros (x = 85.8%) y el más alto contenido proteínico (x = 23.7%). La comparación entre las temperaturas de remojo de 30 y 50§C respecto al rendimiento de harina no fueron significativas (* = 0.05). A nivel de planta piloto, con el remojo de 50§C los rendimientos harineros fueron de 58.0% para la separación de testa en húmedo (H1) y 74.0% para la separación en seco (H2), con porcentajes de proteína de 22.6% y 23.0% para H2. Para elaborar el pan de caja se adicionaron 5, 10 y 15% de harinas H1 y H2 a la de trigo, encontrando que la mezcla con 5.0% de H1 presentaba una buena calidad panadera, proteínica y sensorial, semejante al pan control, de ...