Starch characterization of commercial extruded dry pet foods

Abstract

Starches provide an effective energy source for dogs and cats and can affect health according to its inclusion and extent of digestion. The starch fraction that escapes small intestine (SI) digestion is called resistant starch (RS) and is desirable due to its prebiotic function. Starch is not an essential nutrient for dogs and cats and thus is not reported on commercial pet food labels. Hence, the objective of this work was to characterize starches in commercial pet foods. The top five pet food companies by sales were selected to represent U.S. pet foods, which were divided into four strata with a sampling frame of 654 foods: dog grain based (372 foods), dog grain free (71 foods), cat grain based (175 foods), and cat grain free (38 foods). Five random foods within each stratum were purchased (20 total). Starch analyses (total starch, resistant starch, and starch cook), as well as nutrient analyses were conducted on all foods. Total starch, RS, and starch cook means were compared using a two-group Z-test on dog vs. cat and grain-based (GB) vs. grain-free (GF) diets, and differences were considered significant at a P < 0.05. Total starch was higher (P < 0.05) in dog than cat food, and starch cook was greater (P < 0.05) in GF diets. A regression analysis showed that nitrogen-free extract was a good predictor of total starch. Resistant starch was low and not different among groups. A post hoc test showed that a total sample size of at least 28 diets per group would be required to detect differences in RS between GF and GB diets, if one exists.

Comparison of dietary fibre, β-glucan, resistant and non-resistant starch and <i>in vitro</i> digestibility of commercial extruded dry food of adult dogs

“…3, 11, 12, 23 and 24) with low R-S (≤0.5%) contents contained potato flour (sweet potato, potato starch), pea, some grain flours, oats and wheat as a starch source. In a previous study, it was found that commercial extruded dog and cat foods had low R-S contents and R-S contents even lower than 1% in total starch content (0.703% in cat foods vs 0.945% in dog foods) (Alvarenga and Aldrich, 2020). In the present study, the R-S contents of drytype extruded dog foods were higher than 1.1% in 14 dog food samples (no.…”

“…4, 10, 14, 15, 16, 17, 21, 22, 25 and 29). However, low contents of R-S (<1% DM) in other dog foods in the present study may not be sufficient to improve colon health (Peixoto et al, 2018;Alvarenga and Aldrich, 2020). Peixoto et al (2018) identified that 1.46% R-S in dog food was positively correlated with colonic fermentation, and this R-S content increased butyrate production and improved nutrient absorption.…”

An Assessment of Starch Composition and Gelatinization in Traditional and Non-traditional Dog Food Formulations

“…Characterization studies have examined total starch, resistant starch, and starch cook in commercially available pet foods (Corsato Alvarenga and Aldrich, 2020). Similarity was reported for resistant starch but grain-free diets revealed higher starch cook.…”

“…Prior work has established significant differences associated with manufacturing conditions (Alvarenga & Aldrich, 2020;Alvarenga et al, 2021) with impacts starch gelatinization and resistant starch. Future studies should include in vitro digestibility trials should be conducted to determine the relationship between starch content, starch gelatinization, and digestibility for pet food ingredients commonly utilized in formulations for grain-free diets.…”

Influence of extrusion cooking on physicochemical properties and starch digestion kinetics of Sphenostylis stenocarpa, Cajanus cajan, and Vigna subterranean grains

“…Compared with other hydrothermal/thermal processes such as roasting, boiling, microwaving, and autoclaving, extrusion cooking affords a continuous consolidated multi-operational (involving mixing, heating, pressure cooking and mechanical shearing) process which is energy efficient and produces a high-quality output [19]. Adoption of HTST extrusion by the food and feed industry has resulted in increased production of ready-to-eat snacks and cereals, precooked infant meals, meat and cheese analogues, dry pet foods, fish and livestock ingredients and concentrates using lesser known cereals and legumes [20][21][22][23][24][25][26][27]. This heat processing technique also modifies their molecular structures and nutritional profile.…”