Heat Transfer to Non-Newtonian Fluid Foods under Laminar Flow Conditions in Horizontal Tubes

This paper presents a study of rates of heat transfer to non-Newtonian fluid foods: mango and papaya nectars, passing through horizontal tubes of circular cross section under laminar flow conditions. Determination of the flow and thermal properties of the fluids under study was performed to adequately explain heat transfer experiences. A laminar mixed convection equation was used for describing experimental heat transfer coefficients: Nu = 1.75 [Gz + 0.0083 (Gr_w . Pr_W)^0.75]^1/3 . δ^1/3 . (K_b/K_w)^0.14 The experimental data covered Graetz numbers between 500 and 7000, and were correlated with a mean deviation of 8.4%. The results should be helpful for interpreting heat transfer to pseudoplastic materials in the design of double tube heat exchangers.     

Study on the Complementation of Two Proteins of Low Quality: Black Bean (Phaseolus vulgaris) and Sesame (Sesamun incdicum L.).

In order to determine the complementary potential of black bean and sesame proteins, female rats were fed diets with 10% protein from black bean, sesame or combinations of these. Data showed that diets with these proteins combined had better quality than either protein alone. Maximum protein quality was observed when the two protein sources were mixed in a 1:l (w/w) ratio. This mixturn had PER and NPR values 2 and 5 times higher, respectively, than those of the black bean protein alone and 61 and 71% of the values of PER and NPR, respectively, obtained with a casein diet. Also, there was no alteration of serum or liver lipids.     

GREEN UMBU (SPONDIAS TUBEROSA ARR. CAM.) PRESERVE: PHYSICAL, CHEMICAL AND MICROBIOLOGICAL CHANGES DURING STORAGE

A preserve made from “umbu” in the green state of maturity represents an alternative to avoid losses of the fruit in the mature stage. A factorial experimental design was used to evaluate the effects of formulation, packaging and storage time (0, 45 and 90 days) on the physicochemical, chemical, physical and microbiological characteristics of the preserve during storage under ambient conditions (33C/88% relative humidity). The results showed that the products were microbiologically stable, but that degradation of soluble pectin, reducing sugars and total soluble solids occurred, especially in the cellophane packaging, and this resulted in textural and color changes in the products. The results suggested the incorporation of pectin and glucose syrup and the use of a polypropylene packaging as being the most adequate method of producing and conserving preserves made from this pulp.     

Protein composition of milk from Holstein–Friesian dairy cows and its relationship with the genetic variants A and B of κ-casein and β-lactoglobulin (Part I)

The protein composition and the milk yield (morning milking) were studied in 10 Chilean Holstein–Friesian first lactation dairy cows during the spring season. In addition, the genetic variants A and B of κ-casein (κ-CN) and β-lactoglobulin (β-Lg) were also identified. The results showed that the casein content is significantly affected by the presence of B variant of κ-CN. Moreover, positive interactions between the B variant of κ-CN with AB of β-Lg and the combination of A κ-CN with AA of β-Lg for the total protein content, were found.     

DEVELOPMENT OF A BLENDED NONALCOHOLIC BEVERAGE COMPOSED OF COCONUT WATER AND CASHEW APPLE JUICE CONTAINING CAFFEINE

ABSTRACT

In this work, the stability of a blended beverage composed by coconut water and clarified cashew apple juice (“cajuina”) is presented. The physicochemical, microbiological and sensory stability of a blended nonalcoholic beverage composed of coconut water and cajuina (80:20 v/v) were evaluated during 6 months. The results showed that the beverage presented good stability in all analyzed parameters except for vitamin C, which presented a loss of about 80% of the initial content. The beverage color also presented changes during the storage time. Despite these alterations, the product acceptance during the storage period did not show any rejection.

PRACTICAL APPLICATIONS

The development of blended beverages is a good way of improving the nutritional quality of traditional products. By mixing two or more kinds of fruits, a product with more vitamins and minerals and with different sensory and flavor characteristics when compared to the raw materials is obtained. In the present work, coconut water and cashew apple juice were mixed to obtain a different product combining the nutritional components from both fruits. The blended beverage combines the high vitamin C content of the cashew apple juice with the high mineral level of the coconut water. Caffeine was also added conferring stimulating properties to the product. The product acceptance was evaluated by sensory analysis and presented good acceptance until 6 months of storage at room temperature, presenting the required characteristics for a commercial product.

     

PRESERVATION OF "UMBU" (SPONDIAS TUBEROSA ARRUDA CÂMARA) PULP IN THE GREEN STAGE OF MATURATION BY COMBINED METHODS

“Umbu” (Spondias tuberosa Arruda Câmara) is a typical fruit from northeastern Brazil of considerable economic importance to this region, because several products are derived from it and commercialized, especially the pulp, which can be used as a raw material for preserves and juices. The objective of this research was to study the preservation of umbu in the green stage of maturation by combined methods, including heat treatment and the addition of preservatives and sucrose. The pulps were blanched, pasteurized and mixed with the preservatives and sucrose according to a complete factorial design with three variables (ratio pulp/sucrose, potassium sorbate and sodium metabisulfite), two levels and two repetitions. The products were filled into high‐density polyethylene packages and exposed to a temperature of 40C for 120 days. Physicochemical, color and chemical (SO₂) analyses showed that the concentrations of sodium metabisulfite and potassium sorbate used did not significantly alter product quality. The addition of sucrose significantly decreased the water activity and led to intense browning. The microbiological evaluations showed good product stability for 120 days. The overall results indicated that the heat treatment applied was effective if high levels of hygiene were maintained during the preparatory stages and the packaging materials were well sanitized. The combined preservation methods appear to be an economic way to preserve these high‐acid pulps.     

STORAGE STABILITY OF A STIMULANT COCONUT WATER-CASHEW APPLE JUICE BEVERAGE

Besides flavor, appearance and overall impression, food consumers seek foods rich in nutrients. Fruits are a rich source of nutrients and minerals, and fruit juices are a popular way of consuming them. Development of new products, where two or more kinds of fruit juices are blended to obtain a product that combines the nutritional value of both fruits, which present a different and pleasant taste, has been encouraged by the food industry and has been well accepted by consumers. In this work, the storage stability of a coconut water‐cashew apple juice (87.5:12.5 v/v) beverage was evaluated. Caffeine addition (100 mg/L) conferred stimulating properties to the blend. The physicochemical, microbiological and sensory stability of this blended beverage was evaluated during 6 months. The results showed that the beverage presented good stability for all parameters that were analyzed except for vitamin C, which presented a loss of 58% from the initial content.     

Production of low-fat Chanco cheese using homogenized milk and adjunct lactic culture

The objective of this study was to determine the effect of the partial homogenization of milk and the use of an adjunct lactic culture on the processing, quality and yield of low-fat Chanco cheese.
  Treatments were: T1 normal-fat control and T2 low-fat control. The low-fat treatments were: T3 using homogenized milk, T4 with adjunct lactic culture and T5 both variables.
   It was concluded that the homogenization slightly increased the time of rest after cutting of the curd, and the addition of adjunct lactic culture increased the acidity of whey during a second agitation. Nevertheless, the total time and pH at the end of the process were normal and without significant statistical difference ( P  > 0.05) between treatments. When using homogenized milk the losses of fat in whey decreased by 50% with respect to the low-fat control and nearly 80% in relation to the full fat control. Consequently, the yield was increased. The physical and chemical characteristics of the Chanco cheese were not affected by the studied variables. With respect to the sensory evaluation, significant differences in colour and aroma did not appear, but there were statistically significant differences (P <  0.05) in taste, hardness, adhesiveness, cohesiveness and elasticity between the full-fat control and all the low-fat treatments. In the case of general acceptance, the treatment with adjunct lactic culture was similar to the full-fat control. In addition, it showed the least difference (mild) in elasticity and taste in relation to this control .     

VOLTAGE COLLAPSE AND CONTROL ACTIONS: EFFECTS AND LIMITATIONS

ABSTRACT

This paper focuses on control actions determination for voltage collapse prevention. Sensitivity matrices are proposed based on the knowledge of the critical bus. By critical bus one means that bus whose state variables vary at most at the voltage collapse point. A tangent vector is used to identify the critical bus, and its behavior as a function of load increase is also investigated and compared with other indices previously proposed. It is shown that generator control actions may not work to increase voltage collapse margin, whereas local control actions may produce better results. The tests are carried out in the IEEE-300 bus test system, with and without reactive power limits consideration.