Fiber is currently used in dog food formulations due to its nutritional properties. However, few studies have evaluated the influence of fiber on the extrusion traits and kibble formation. The present study evaluated the effect of fiber type and particle size on extrusion processing parameters and kibble macrostructure of dog foods. In treatment 1, guava fiber was added to a control formula (CO) at different inclusion levels: 3% (GF3), 6% (GF6), and 12% (GF12). In treatment 2, two fiber types (sugarcane and wheat bran) and two fiber particle sizes were compared to a control (CO) product. Foods were manufactured using a single screw extruder. Each food was processed on two separate days and samples were collected four times per run, for a total of eight replications per diet. The processing conditions were not changed for any treatment. Data were analyzed via analysis of variance, and compared by polynomial contrasts for treatment 1, and by defined orthogonal contrasts for treatment 2 (P < 0.05). Guava fiber inclusion resulted in a linear increase in temperature, pressure, and specific mechanical energy (SME) input (P < 0.001) during extrusion, whereas starch cooking (assessed by the amyloglucosidase method) and radial expansion decreased linearly (P < 0.001). Kibble density and cutting force increased linearly (P < 0.001) with guava fiber inclusion. In treatment 2, fiber addition also increased SME (P < 0.001) and decreased radial expansion (P = 0.008). However the latter was compensated by an increase in longitudinal expansion in the case of sugarcane fiber, resulting in no change in kibble density. Cutting force was higher (P < 0.001) for fiber supplemented foods, similar to treatment 1, but sugarcane fiber had a higher impact on hardness than wheat bran (P < 0.001). The finely ground fibers led to higher starch gelatinization (P < 0.05) and kibbles with lower piece density (P = 0.018). To summarize, insoluble fibers such as guava fiber, sugarcane and wheat bran at high inclusion rate increase the electric energy required to extrude, may reduce starch cooking and result in the production of less expanded, denser and harder kibbles. However, kibble characteristics are also significant impacted by fiber type and particle size.

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Simple SummaryThe results from this research indicate that fibers have an effect on extruded pet food texture and palatability. These results may help pet food companies select ingredients for successful product formulations.AbstractThe objectives of this study were to determine (a) the influence of fiber on the sensory characteristics of dry dog foods; (b) differences of coated and uncoated kibbles for aroma and flavor characteristics; (c) palatability of these dry dog foods; and (d) potential associations between palatability and sensory attributes. A total of eight fiber treatments were manufactured: a control (no fiber addition), guava fiber (3%, 6%, and 12%), sugar cane fiber (9%; large and small particle size), and wheat bran fiber (32%; large and small particle size). The results indicated significant effects of fibers on both flavor and texture properties of the samples. Bitter taste and iron and stale aftertaste were examples of flavor attributes that differed with treatment, with highest intensity observed for 12% guava fiber and small particle size sugar cane fiber treatments. Fracturability and initial crispness attributes were lowest for the sugar cane fiber treatments. Flavor of all treatments changed after coating with a palatant, increasing in toasted, brothy, and grainy attributes. The coating also had a masking effect on aroma attributes such as stale, flavor attributes such as iron and bitter taste, and appearance attributes such as porosity. Palatability testing results indicated that the control treatment was preferred over the sugar cane or the wheat bran treatment. The treatment with large sugarcane fiber particles was preferred over the treatment with small particles, while both of the wheat bran treatments were eaten at a similar level. Descriptive sensory analysis data, especially textural attributes, were useful in pinpointing the underlying characteristics and were considered to be reasons that may influence palatability of dog foods manufactured with inclusion of different fibers.

This article highlights the need for an active role for building physics in the development of near-zero energy buildings while analyzing an example of an integrated system for the upgrade of existing buildings. The science called either Building Physics in Europe or Building Science in North America has so far a passive role in explaining observed failures in construction practice. In its new role, it would be integrating modeling and testing to provide predictive capability, so much needed in the development of near-zero energy buildings. The authors attempt to create a compact package, applicable to different climates with small modifications of some hygrothermal properties of materials. This universal solution is based on a systems approach that is routine for building physics but in contrast to separately conceived sub-systems that are typical for the design of buildings today. One knows that the building structure, energy efficiency, indoor environmental quality, and moisture management all need to be considered to ensure durability of materials and control cost of near-zero energy buildings. These factors must be addressed through contributions of the whole design team. The same approach must be used for the retrofit of buildings. As this integrated design paradigm resulted from demands of sustainable built environment approach, building physics must drop its passive role and improve two critical domains of analysis: (i) linked, real-time hygrothermal and energy models capable of predicting the performance of existing buildings after renovation and (ii) basic methods of indoor environment and moisture management when the exterior of the building cannot be modified.

Simple SummaryThe results of this research indicate that processing (baked vs. extruded) plays an important role in determining pet food product texture. In addition, raw ingredients (fresh meat vs. meal-based) did not consistently affect product sensory characteristics. These results may help pet food technologists better understand factors that affect palatability.AbstractThe pet food industry is an important portion of the food and feed industries in the US. The objectives of this study were (1) to determine cooking method (baking or extrusion), meat inclusion (0 or 20%), and extrusion thermal to mechanical energy ratios (low, medium, and high) effects on sensory and volatile properties of pet foods, and (2) to determine associations among sensory and volatile characteristics of baked and extruded pet foods. Descriptive sensory analysis and gas chromatography-mass spectrometry were used to analyze the pet food samples. It was found that baked samples were lighter in color (2.0–2.6 baked vs. 3.5–4.3 extruded, color intensity scale 0–15), and had lower levels of attributes that indicated rancidity (i.e., fishy flavor; 0.3–0.6 baked, 0.6–1.5 extruded, scale 0–15), whereas extruded pet foods were more cohesive in mass, more friable, hard, and crisp, but less powdery than baked samples. Fresh meat inclusion tended to decrease bitterness and increase fishy flavor and cohesiveness of pet foods. High thermal to mechanical energy ratio during extrusion resulted in less musty and more porous kibbles. The main volatile compounds included aldehydes, such as hexanal and heptanal, ketones, and alcohols. Extruded samples did not contain methylpyrazine, while baked samples did not contain 2-butyl furan. Future studies should consider evaluating the relationship between sensory results and animal palatability for these types of foods.