Anaerobic treatment of residual lemon pulp in digesters with semi-continuous feed.

Lemon growing areas in the north of Argentina have industries that produce concentrated juice, peel and essential oil and generate a significant amount of liquid and solid waste as lemon pulp. In Argentina, despite the potential applications that the pulp has as animal feed and human and industrial raw material, only 10% is used for these purposes and the rest is discarded into the environment causing many ecological and economic problems. There is little information in the literature on biotechnologies for the treatment of this industrial waste. This paper shows that lemon pulp is a suitable substrate to be treated by anaerobic digestion. We obtained 86 and 92% reduction of chemical oxygen demand in a digester with a semi-continuous feed and retention time of 10 and 20 days respectively and a productivity of 0.406 g CH(4)/g VS h. Comparative tests showed that pre-digesting the pulp improved the process of digestion and increased biogas generation by 20%.

Vitamin B6 status improves in overweight/obese women following a hypocaloric diet rich in breakfast cereals, and may help in maintaining fat-free mass.

OBJECTIVE: To analyze the changes in vitamin B6 status in women following slightly hypocaloric diets based on the relative increase consumption of foods whose intakes are below those recommended, and to study how these changes influence the proportion of fat-free mass. DESIGN: Intervention study of two slightly hypocaloric diets: diet V (increased consumption of vegetables), or diet C (increased consumption of cereals, especially breakfast cereals). SUBJECTS: A total of 49 women with a body mass index (BMI) of 25-35 kg/m2. MEASUREMENTS: Dietetic, anthropometric and biochemical data were collected at the start of the study and at 2 and 6 weeks. RESULTS: Both the C and V subjects showed a reduction in their energy intake, body weight, BMI and fat mass. Pyridoxine intake increased in both groups and plasma pyridoxal phosphate (PLP) levels increased only with diet C. An association was found between the increase in plasma PLP at 6 weeks and the increase in pyridoxine intake (r=0.451; P<0.01). Multiple regression analysis showed a positive association between the increase in PLP at the end of the study and the increases in the pyridoxine intake, B6 density or B6/protein ratio. At the end of the study, and only in those women whose PLP levels were increased, the higher the increase in PLP level, the higher the increase in fat-free mass percentage (r=0.4426, P<0.05). CONCLUSIONS: Interventions aimed at weight control should also try to maintain or improve nutritional status. A diet rich in cereals (especially fortified breakfast cereals) appears to be useful in improving vitamin B6 status. Such an improvement could help maintain fat-free mass during periods of weight loss.

Regulation of the production of polygalacturonase by Aspergillus niger.

Synthesis of ethylene in static cultures as well as the effect of endogenous and exogenous ethylene on the synthesis of polygalacturonase by Aspergillus niger were determined. This strain produced maximum ethylene amounts when cultured at 30 degrees C for 3 d. The effect of adding ethylene precursors (citrate-cycle intermediates) on ethylene production was investigated. Best intracellular and extracellular polygalacturonase production was obtained with 2-oxoglutaric, pyruvic and fumaric acids, and with glutamic acid too. Addition of ethylene to the culture medium also increased the synthesis of polygalacturonase, although to a lower degree than when glutamic acid was added.

The influence of vitamin B2 intake on the activation coefficient of erythrocyte glutation reductase in the elderly.

OBJECTIVE: To evaluate the influence of dietetic vitamin B2 on the activation coefficient of erythrocyte glutation reductase (alpha-EGR) of a group of elderly people. DESIGN: The study subjects were 133, independently-living elderly people, between 65 and 90 years of age. A dietetic study was performed using a 7-day food record. Riboflavin status was measured by determining the alpha-EGR. RESULTS: Some 23.9% of subjects had riboflavin intakes lower than those recommended. At the biochemical level, 9.8% of subjects (7.7% of men and of 10.6% women) showed alpha-EGR>1.2. Those subjects with riboflavin intakes below 90% of those recommended showed significantly higher alpha-EGR levels (1.15+/-0.16), an indication of a poorer riboflavin status at the biochemical level. Those with greater intakes showed lower alpha-EGR values (1.05+/-0.10). Furthermore, the mean consumption of dairy products (an important source of this vitamin) by subjects is insuficiente (341.1+/-159.8 g/day, 2.1+/-1 servings/day). The data show that those with riboflavin intakes below those recommended took 204.7+/-89.4 g/day of milk products (1.3+/-0.5 servings/day) compared to the 384+/-153.1 g/day (2.4+/-1 servings/day) (p<0.001) consumed by those with higher riboflavin intakes. CONCLUSION: Although the mean riboflavin intake is acceptable, there remain some insufficiencies that require attention. It would seem advisable to recommend the elderly increase their intake of milk products. This would be especially important for subjects who take less than two rations per day.

Effects of inoculum size on ethanol inhibition modeling and other fermentation parameters.

The effects of inoculum size on the kinetics of ethanol fermentation are not well defined in the literature. The purpose of this article is to examine the influence of the initial cell concentration on the modeling of ethanol inhibition. Experimental results show that increasing the inoculum level decreases the severity of ethanol inhibition. The effect of cell concentration can be related to the different inhibitory effects of autogeneously produced versus extracellularly added ethanol. On this basis, it is concluded that the extracellular ethanol concentration in the fermentation media is not the only variable to account for product inhibition modeling. Other fermentation parameters, such as yields and maintenance coefficients, are presented at different levels of initial cell concentration.

Producción de etanol por fermentación con alta concentración de levaduras: su aplicación en destilerías ya instaladas / Production of ethanol by fermentation with high concentration or yeasts: its application in formely installed distilleries

Como consecuencia de la crisis energética mundial, se están realizando numerosas investigaciones sobre la obtención de alcohol etílico por fermentación, con el objeto de disminuir su costo de producción. En el campo de la biotecnología se han propuesto diversos sistemas de fermentación, algunos con buenos resultados. Sin embargo en nuestro país se continúa trabajando con el sistema tradicional en lotes, seguramente por la gran inversión que requiere un cambio de tecnología. El objetivo de este trabajo es ponderar las posibilidades de realizar fermentaciones en lotes con alta concentración de levaduras, con el fin de aumentar la productividad volumétrica, es decir la cantidad de etanol producida por litro de mosto y por hora. Se estudió la realción entre la concentración de levaduras en el medio de fermentación y las productividades volumétrica y específica, la primera aumenta y la segunda disminuye a medida que se incrementa la concentración de microorganismos, ambas de manera no lineal. Ensayos de fermentación en lotes con reutilización de levaduras mostraron la dificultad de mantener una población superior a 300 x 10**6 lev/ml. La propagación periódica (cada 13 lotes) de las levaduras recuperadas demostró ser un método sencillo y efectivo para mantener concentraciones altas de microorganismos en el medio de fermentación, lo que se traduce en una productividad mayor que la obtenida en el proceso en lotes convencional con recuperación de levaduras. Las aplicación de estas experiencias a nivel industrial no implicaría ningún tipo de modificación, ni la incorporación de equipos adicionales en las destilerías que actualmente trabajan con el sistema Melle Boinot (AU)

Producción de etanol por fermentación con alta concentración de levaduras: su aplicación en destilerías ya instaladas / Production of ethanol by fermentation with high concentration or yeasts: its application in formely installed distilleries

Como consecuencia de la crisis energética mundial, se están realizando numerosas investigaciones sobre la obtención de alcohol etílico por fermentación, con el objeto de disminuir su costo de producción. En el campo de la biotecnología se han propuesto diversos sistemas de fermentación, algunos con buenos resultados. Sin embargo en nuestro país se continúa trabajando con el sistema tradicional en lotes, seguramente por la gran inversión que requiere un cambio de tecnología. El objetivo de este trabajo es ponderar las posibilidades de realizar fermentaciones en lotes con alta concentración de levaduras, con el fin de aumentar la productividad volumétrica, es decir la cantidad de etanol producida por litro de mosto y por hora. Se estudió la realción entre la concentración de levaduras en el medio de fermentación y las productividades volumétrica y específica, la primera aumenta y la segunda disminuye a medida que se incrementa la concentración de microorganismos, ambas de manera no lineal. Ensayos de fermentación en lotes con reutilización de levaduras mostraron la dificultad de mantener una población superior a 300 x 10**6 lev/ml. La propagación periódica (cada 13 lotes) de las levaduras recuperadas demostró ser un método sencillo y efectivo para mantener concentraciones altas de microorganismos en el medio de fermentación, lo que se traduce en una productividad mayor que la obtenida en el proceso en lotes convencional con recuperación de levaduras. Las aplicación de estas experiencias a nivel industrial no implicaría ningún tipo de modificación, ni la incorporación de equipos adicionales en las destilerías que actualmente trabajan con el sistema Melle Boinot

[Production of ethanol by fermentation with a high concentration of yeasts. Its application in already installed distilleries]. / Producción de etanol por fermentación con alta concentración de levaduras. Su aplicación en destilerías ya instaladas.

Due to the dramatic increase in international oil prices, the ethanol production by fermentation is presently becoming an attractive and feasible project for many countries Argentina has implemented an experimental national program of ethanol use as fuel and the standard procedure of Melle-Boinot is currently employed in sugar cane molasses fermentation. The aim of this work was to improve the overall efficiency of the batch process by recycling high levels of yeast biomass. It was observed that the volumetric productivity increased with biomass concentration, whereas the specific productivity decreased. Both variations were not linear (Fig. 1). It was difficult to keep a yeast concentration higher than 3 x 10(8) cell/ml during batch fermentation assays. Anyhow the periodic subculturing of yeast biomass (every 13 recycling periods) proved to be an effective method to obtain a high cell density in the fermentation medium (Fig. 2). The industrial application of data reported here would not imply additional investment or equipment to distilleries using standard fermentation procedures.

Producción de etanol por fermentación con alta concentración de levaduras. Su aplicación en destilerías ya instaladas. / [Production of ethanol by fermentation with a high concentration of yeasts. Its application in already installed distilleries]

Due to the dramatic increase in international oil prices, the ethanol production by fermentation is presently becoming an attractive and feasible project for many countries Argentina has implemented an experimental national program of ethanol use as fuel and the standard procedure of Melle-Boinot is currently employed in sugar cane molasses fermentation. The aim of this work was to improve the overall efficiency of the batch process by recycling high levels of yeast biomass. It was observed that the volumetric productivity increased with biomass concentration, whereas the specific productivity decreased. Both variations were not linear (Fig. 1). It was difficult to keep a yeast concentration higher than 3 x 10(8) cell/ml during batch fermentation assays. Anyhow the periodic subculturing of yeast biomass (every 13 recycling periods) proved to be an effective method to obtain a high cell density in the fermentation medium (Fig. 2). The industrial application of data reported here would not imply additional investment or equipment to distilleries using standard fermentation procedures.