NUTRITION ▶▶▶


Figure 2 - Ileal in vitro digestibility of organic matter and starch of wheat in relation to gelatinisation technique.


100


Ileal in vitro digestibility organic matter Ileal in vitro digestibility starch


75 50 25 0


Untreated wheat


Gelatinised wheat


micronising


Source: Schothorst Feed Research, 2008. * Presco


Figure 3 - Scheme of the pressure cooking process used in Weert, the Netherlands.


Clean grains


Gelatinised wheat


steam flaking


Gelatinised wheat


expansion


Gelatinised wheat


(pressure cooled)*


BAR Puffer High pressure High temperature steam Tunnel


Puffed grains


Figure 4 - In vivo trial with 196 piglets. Body weight (kg)


20 18 16 14 12 10 8 6


Gelatinised corn* Alternative corn source


start Body weight day 15 Body weight * Presco Baby Corn, Limagrain Ingredients. 28 ▶ PIG PROGRESS | Volume 37, No. 8, 2021 day 29 Body weight


850 750 650 550 450 350 250 150


What does gelatinisation mean? In feed production, gelatinisation of starch sources is a pro- cessing step that can help in this context. Gelatinisation ex- poses starch sources to heat and water to break down their molecules, with the result of increasing the starch’s digestibil- ity. There are various different methods. One of the more ex- pensive methods is puffing – or pressure cooking. This proce- dure is widely used for creating human nutrition – one only has to think of popcorn – but there are not many places in the world where the sophisticated technology is used for ani- mal nutrition. In short: the pressure-cooking process starts with a whole grain (corn, but also wheat, barley, rice, etc.) and from that produces a good quality, digestible and palatable ingredient. Figure 3 shows an illustration of the pressure-cooking process, based on a combination of pressure, steam and time. Clean grains go to the puffer at high pressure (20–25 bar) and with overheated steam (from 250–300°C). The grains stay there for a few seconds, then the pressure is reduced abruptly. The grains are then shot to the tunnel and will subsequently pop. That is because the water in the starch granules evaporates, resulting in the granules swelling instantly. It is known that 1 mol of water in liquid form occupies much less space than steam. When the steam evaporates, it digs holes in starch granules, thus the crystalline structure is completely broken down like popcorn (starch gelatinisation). Then the puffed grains are cooled instantly. The pictures show the difference between native starch gran- ules and starch granules after the pressure-cooking process. Intact starch granules are visible in native grains (red circles on the picture). After pressure cooking, the starch granules


Feed intake (g/d)


Gelatinised corn* Alternative corn source


piglets may refuse to eat solid feed and develop anorexia, fur- ther resulting in atrophy of intestinal cells. Therefore, pre-con- ditioning piglets with solid feed rich in cereals is an important step to teach them how to eat solids after weaning. Normal practice on a farm is to provide pre-gelatinised creep feed.


Day 1-8 Prestarter


day 1-15 Prestarter


day 15-29 Starter


day 1-29 Total


Ileal digestibility (%)


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