DOI: 10.5937/FFR1801027S UDK 641.56:633.11+633.13]:66.022.392 Original research paper COMPARATIVE STUDY ON THE PHYSICO-CHEMICAL, TEXTURAL AND THERMAL PROPERTIES OF INSTANT PORRIDGES BASED ON SPELT AND OATS Olivera D. Šimurina*, Bojana V. Filipčev, Boško D. Marić, Biljana R. Cvetković, Marija I. Bodroža Solarov University of Novi Sad, Institute of Food Technology, 21000 Novi Sad, Bulevar cara Lazara 1, Serbia *Corresponding author: Phone: +381 21 485 3778 E-mail address: [email protected] ABSTRACT: Changing of food habits and increased preference for healthy meals, along with the growth of breakfast industry has increased the size of “ready-made“ and instant porridge market in Serbia. Porridges dominantly marketed are those based on oats. However, there is a growing interest of local producers to use other cereals for porridge production. Therefore, this work was aimed to estimate the porridge-making ability of spelt wheat (Triticum aestivum spp. spelta) in comparison to that of oats. The studied porridges are instant products, based on extruded spelt or oat flour. The proximate composition, hydration properties (water absorption index-WAI and water solubility index- WSI), consistency and thermal properties were determined with the aim to compare the characteristics of the porridges. In general, the spelt-based porridge had more total and insoluble fibреs, proteins, minerals and less available carbohydrates in comparison to the oat porridge. The spelt porridge may be eligible to bear the nutritional claim „high-fibre“ which is advantageous for the market viability of the product. Both porridges had >20% of damaged starch due to high initial content in the flours and extrusion processing of flours, though spelt-based extrudate and porridge were significantly higher in this parameter. Oat-based extrudate and porridge were higher in resistant starch content. The consistency was similar between the porridges, although spelt tended to form slightly firmer and cohesive porridge. Spelt porridge had better hydration properties (higher WAI) which are a featured attribute for this kind of product, similarly to higher consistency values. Spelt wheat, in its extruded form, is a suitable ingredient for porridge production. Key words: porridge, spelt, oats, hydration, composition, consistency, gelatinization INTRODUCTION Porridge is a traditional and staple food in rations (Khan et al., 2014) and in the case many countries, especially developing of food emergency situations. Traditional ones. In modern cultures, porridge is en- porridges in developing countries are joying a revival as a healthy breakfast based on local staple cereals (wheat, rice, food. Porridge is a convenient food for millet, sorghum, maize) and starchy tubers weaning infants, elderly and convales- (cassava, potato and plantain). Cereal- cents due to easy digestibility (Rhim et al., based porridges are usually prepared by 2011). It is also very useful food for mi- cooking of cracked or previously soaked litary troops as it can be produced to be grains. In Northern Europe and North light in weight and long in shelf-life which America, porridge is usually made from makes it convenient for operational pack oats cooked in water and/or milk but it can 27 Olivera Šimurina et al., Comparative study on the physico-chemical, textural and thermal properties of instant porridges based Olivera Šimurina et al., Comparative study on the physico-chemical, textural and thermal properties of instant porridges based on spelt and oats, Food and Feed Research, 45 (1), 27-35, 2018 on spelt and oats, Food and Feed Research, 45 (1), 27-35, 2018 be prepared from maize, barley and rice the quality parameters of spelt and oat in- standard methods: moisture (No. 926.5), temperatures and enthalpy of gelatine- as well. Depending on the proportion of stant porridges, in order to evaluate the ash (No. 930.22), crude proteins (No. zation (H) were determined. Gelatiniza- the cereals and liquid, two types of por- feasibility of spelt wheat for this product 950.36), fat (No. 935.38), dietary fibres tion temperatures and enthalpy changes ridges prepared for consumption can be type. The instant porridges were based on (No. 958.29). Carbohydrates were ob- were calculated using Proteus Thermal distinguished: thick and thin porridges. extruded spelt and oat flour and were tained by calculation according to Analysis software (Netzsch, Germany). Thick porridges are solid-like and can be formulated to bear a „high-protein“ nutri- FAO/WHO guidelines using the equations Determination of textural properties eaten with spoon or hand whereas thin tional claim (min. 20% energy comes from 1 and 2 (FAO, 2003): porridge or gruel is consumed by drinking protein (Regulation (EC) No. 1924/2006)). Total carbohydrates (g/ 100 g) = 100-(protein+ A Texture Analyser (TA-XTplus, SMS, as having fluid or semi-fluid consistency fat + water + ash + alcohol) (1) Godalming, England) was used to mea- (Moussa et al., 2011). Thin porridge is MATERIALS AND METHODS sure the consistency and cohesiveness of Available carbohydrates (g/100 g) = 100- usually used as a complementary meal for Materials the samples according to the back-ex- infants. (protein+ fat + water + ash + alcohol + total trusion method. Measurements were per- Spelt and oat flours and extrudates were fibre) (2) Today, development of food processing formed in a beaker in which the samples kindly donated from local producer Damaged and resistant starch contents of were mixed with warm water as explained technologies enabled the production of „BioLutisа“d.o.o., Mošorin, Serbia. The „ready-made“ porridges which do not need the samples were determined according to above (paragraph Materials). A 35-mm whole grain flours were obtained by abra- procedures given in the Damaged Starch disc probe was used to penetrate the sam- long preparation and are convenient for sive milling on a stone grinder mill, after use. Oats for porridge are processed by and Resistant Starch Assay Kits (Mega- ples. All measurements were made in five thorough cleansing and dehulling of zyme International Ltd., Wicklow, Ireland). replications after cooling of the samples to (hydro) thermal treatments (kilning, stea- grains. The grinded material was sifted feeding temperatures (37 C). An indicator ming), sizing, cutting and flaking. Different and flour fraction between 180 and 350 Determination of hydration properties of firmness was an area under the curve forms of porridge oats can be distin- μm was used to produce extrudates. Ex- Water absorption index (WAI) and water registered during the penetration of the guished: pinhead (outer husk not re- trusion was performed on a single-screw solubility index (WSI) were the parameters probe into the sample. Cohesiveness was moved), rolled oat flakes (removed outer extruder under the following processing to describe the hydration properties of measured as a peak force registered upon husk, groats steamed, flattened and parameters: temperature 180 °C, time 150 porridges. WAI and WSI of the porridges the probe return and it is actually an rolled), steel-cut oats or Irish oats (re- s, pressure 150 bar, shear rate≥ 100 s-1, were determined as outlined in Yadav et indication of the sample’s resistance to moved outer husk, groats cut into 2-3 screw rotating speed 500 rpm and energy al. (2014) and Mandge et al. (2014). 3 g of flow off of the disc. The test settings were: pieces), Scottish oatmeal (groats stone- consumption 1.8 MJ/kg. After extrusion, sample was dispersed in 30 ml distilled test speed 1.0 mm/s, trigger force 10 g grinded instead of steel cut). Rolled oat extrudates were ground on a hammer mill. flakes can be regular, quick (thinner fla- water at room temperature and gently and travel distance 30 mm. High-protein dry instant porridges were stirred. After 30 min hydration, the dis- kes, more steamed) or instant (pre-co- Statistical analysis oked, rolled even thinner, dehydrated). finally prepared by blending the grinded persion was centrifuged at 3000 x g for 10 extruded spelt or oat with other ingredients min. Supernatant was carefully decanted Experimental data were statistically analy- Extrusion cooking is a processing techno- following the proportion in the formulation: into weighted evaporated dish and dried to sed by means of one-way ANOVA follo- logy widely used to produce „ready-to-eat“ extrudate (100 g), oat flakes (23.1 g), soy constant mass at 110 C. The remaining wed by Tukey’s (HSD) post-hoc test and breakfast cereals, expanded snacks and protein isolate (23.1 g), caseine (23.1 g), gel was weighed and WAI (g/g) was ex- considering significant values at p0.05 instant cereal-based foods. Extrusion of- and xylitol (23.1 g). The other ingredients pressed as the ratio of gel weight and dry (software Statistica 13, Tulsa, OK). fers many advantages to processors: high used in porridge formulation were pro- weight of sample. WSI (%) was expressed throughput, energy efficiency, thermal con- cured from local food stores and their ori- as the percentage of dried supernatant in RESULTS AND DISCUSSION trol, short processing time and ability to in- gin is as follows: oat flakes ‘‘Italico”, Bečej, dry weight of sample. corporate wide variety of ingredients to the Serbia; soy protein isolate ‘‘Yucheng Composition DSC measurements final product (Eastman et al., 2001). Ex- Crown Soya Protein Foods Co.” Ltd., Chi- Spelt flour had higher content of proteins, trusion is a convenient way to produce in- na; Na-caseinate Rovita FN 5 S ‘‘Rovita” DSC studies of oat/spelt flour, grinded ex- ash, total and insoluble fibres in com- stant cereal porridges which require mi- GmbH, Germany, xylitol ‘‘Danisco Cultor trudate and dry porridge blend samples parison to oat flour which was higher in fat nimum preparation time-simple, quick re- AG”, Switzerland. were performed on a differential scanning and soluble fibre content (Table 1). These constitution with warm or cold water or Reconstituted porridge was prepared by calorimeter DSC 204F1 Phoenix (Netzsch, relations remained similar after extrusion milk.