Determination of lipids and fatty acids in infant formula: comparison of the conventional x direct method / Lipídios e ácidos graxos em fórmula infantil: comparação de metodologias de extração convencional x direta

Lipids in food are conventionally analyzed in two stages: extraction with organic solvent and fat esterification reaction, in this case, the type of fat of each food influences the choice of extraction and esterification reagents. In the direct method, such procedures are performed in one step. This work compared the conventional extraction method and quantification of lipids and fatty acids, with a direct method in infant formula. A reference sample of infant formula conteining certified lipids and fatty acids values from the National Institute of Standards and Technology was used. The conventional method for lipid analysis used the acid hydrolysis method; for the determination of fatty acids, the fats were extracted with a mixture of ethyl ether and petroleum ether. The direct method consisted of direct trans esterification with sodium methoxide. In the analysis of fatty acids, the majority of the results showed statistically equal values (α < 0.05) for both methods. The direct method proved suitable, mainly because of reduction in analytical time and quantity of solvents (AU).

Os lipídios em alimentos são analisados, de forma convencional, em duas etapas: extração com solvente orgânico e reação de esterificação da gordura, neste caso o tipo de gordura de cada alimento influencia na escolha dos reagentes da extração e esterificação. No método direto, estes procedimentos são realizados em uma etapa única. Este trabalho comparou a metodologia convencional de extração e quantificação de lipídios e ácidos graxos, com um método direto em fórmula infantil. Foi utilizada uma amostra de referência de fórmula infantil com valores certificados para lipídios e ácidos graxos da Nacional Institute of Standards and Technology. A metodologia convencional para a análise de lipídios empregou método com hidrólise ácida; para a determinação dos ácidos graxos, a gordura foi extraída com uma mistura de éter etílico e éter de petróleo. O método direto fundamentou-se na transesterificação direta com metóxido de sódio. Na análise dos ácidos graxos, a maioria dos resultados demonstrou valores estatisticamente iguais (α < 0,05) para os dois métodos. O método direto demonstrou ser apropriado, principalmente pela diminuição do tempo de análise e quantidade de solventes (AU).

Effects of a moderate iron overload and its interaction with yacon flour, and/or phytate, in the diet on liver antioxidant enzymes and hepatocyte apoptosis in rats.

The effect of moderate Fe overload in the diet and its interaction with phytate, and/or yacon flour (YF), recognized as an inhibitor, and facilitator, of Fe absorption, respectively, was evaluated in healthy rats. For this purpose the following parameters were analyzed: (1) apparent iron (Fe), copper (Cu) and zinc (Zn) absorption; (2) blood Fe; (3) blood lipids (cholesterol, tryacylglicerol); (4) blood AST and ALT; (5) liver histology (histopathology, hemosiderin depots, apoptosis index; (6) liver fatty acid incorporation; (7) liver antioxidant enzyme activity. Moderate Fe overload may cause change in some liver markers (hemosiderin depots, apoptosis index and GPx) and blood lipids (total cholesterol and VLDL) and the interaction with yacon flour, and phytate, in the Fe overloaded diets may exert a protective effect on these alterations.

Comparison of Goto-Kakizaki rats and high fat diet-induced obese rats: Are they reliable models to study Type 2 Diabetes mellitus?

Type 2 Diabetes mellitus (T2DM) is an evident growing disease that affects different cultures throughout the world. T2DM occurs under the influence of three main factors: the genetic background, environmental and behavioral components. Obesity is strongly associated to the development of T2DM in the occident, while in the orient most of the diabetic patients are considered lean. Genetics may be a key factor in the development of T2DM in societies where obesity is not a recurrent public health problem. Herein, two different models of rats were used to understand their differences and reliability as experimental models to study the pathophysiology of T2DM, in two different approaches: the genetic (GK rats) and the environmental (HFD-induced obese rats) influences. GK rats were resistant to weight gain even though food/energy consumption (relative to body weight) was higher in this group. HFD, on the other hand, induced obesity in Wistar rats. White adipose tissue (WAT) expansion in this group was accompanied by immune cells infiltration, inflammation and insulin resistance. GK rats also presented WAT inflammation and insulin resistance; however, no immune cells infiltration was observed in the WAT of this group. Liver of HFD group presented fat accumulation without differences in inflammatory cytokines content, while liver of GK rats didn't present fat accumulation, but showed an increase of IL-6 and IL-10 content and glycogen. Also, GK rats showed increased plasma GOT and GPT. Soleus muscle of HFD presented normal insulin signaling, contrary to GK rats, which presented higher content of basal phosphorylation of GSK-3ß. Our results demonstrated that HFD developed a mild insulin resistance in Wistar rats, but was not sufficient to develop T2DM. In contrast, GK rats presented all the typical hallmarks of T2DM, such as insulin resistance, defective insulin production, fasting hyperglycemia/hyperinsulinemia and lipid plasma alteration. Thus, on the given time point of this study, we may conclude that only GK rats shown to be a reliable model to study T2DM.

Effects of dietary lipid composition and inulin-type fructans on mineral bioavailability in growing rats.

OBJECTIVE: This study reports the effects of feeding with a combination of inulin-type fructans (ITF) and fish oil (FO) on mineral absorption and bioavailability as part of a semipurified diet offered to rats. METHODS: Male Wistar rats (n = 24) were fed a 15% lipid diet (soybean oil [SO] or a 1:0.3 fish:soybean oil mixture [FSO]) and diets containing the same sources of lipids supplemented with 10% ITF (Raftilose Synergy 1) ad libitum for 15 d. Feces and urine were collected for mineral analyses during the last 5 d of the test period. Fatty acid composition was determined in liver and cecal mucosa homogenates. Liver and bone mineral analyses were performed by atomic absorption spectrophotometry. Bone biomechanical analyses were evaluated by a 3-point bending test. RESULTS: Compared with the controls, ITF-fed rats had enlarged ceca and a significant decrease in cecal content pH (P < 0.001). The apparent mineral absorption was improved in these rats, and this effect was enhanced by dietary combination with FO for all minerals except for magnesium. Addition of ITF to the diet resulted in higher bone mineral content (calcium and zinc) and bone strength, but increased bone mineral content was only statistically significant in FO-fed animals. A decrease in liver iron stores (P = 0.015) was observed in rats fed FO, considering that ITF consumption returned to levels comparable to the SO control group. CONCLUSION: These findings confirm the positive influence of ITF on mineral bioavailability, which was potentiated by addition of FO to the diet.