Individual Heat Transfer Modes During Baking of “Mlinci” Dough

During baking of “Mlinci” dough in a batch oven heat was transferred by conduction and convection. Heat transfer by radiation in this case can be neglected due to oven design. The major portion of heat transfer was by conduction (96.09%) and minor portion by convection (3.91%). Different thermal parameters, e.g., specific heat, thermal conductivity and thermal diffusivity of „Mlinci” dough were determined. Individual mathematical models for each type of heat transfer were proposed. They were obtained by average values of thermal parameters; for thermal conductivity 0.494 W/m °C, for specific heat 2.257 kJ/kg °C for thermal diffusivity 2.034·10-7 m2/s, for density 1076 kg/m3 and for free convection heat transfer coefficient 9.756 W/m2 °C. Since the major portion of heat during baking of “Mlinci” dough in batch oven was transferred by conduction therefore the amount of heat supplied to the product can be controlled by individual models for conduction

Enzymatic Activity in Wheat Seeds of Different Protein Content

We have examined buffer soluble protein content and oxido-reductive and proteolytic enzyme activities of three wheat cultivars with different total protein content. The amount of extracted proteins was lower in wheat with lower total protein content. Activity of glutathione reductase (GR), catalase (CAT), peroxidase (POX) and aspartate protease (phytepsin) was unaffected by differences in total protein content of examined wheat, except in case of peroxidase activity in Srpanjka cultivar. Activity of lypooxigenase (LOX), arginyl and phenylalanyl aminopeptidase (Arg-AP; Phe-AP) was proportionally lower in wheat with lower total protein content. Polyphenoloxidase (PPO) activity was significantly lower, while carboxypeptidase I (CP-I) activity increased with decrease of total protein content. The obtained results indicate that total protein content of wheat affecting the amount of extractable proteins as well as activity of LOX, Arg-AP and Phe-AP, while activities of GR, CAT, POX, PPO, CP-I and phytepsin seem unaffected by total protein content

Effect of apple by-product as a supplement on antioxidant activity and quality parameters of pasta

In this study, pasta was prepared by replacement of durum semolina (DS) with 10% and 15% of apple peel powder (APP). The control sample was pasta made from 100% DS. Total phenolic content (TPC), antioxidant capacity (AOA) and quality parameters of pasta were determined before and after cooking. Extraction of phenolics with methanol and ethanol, assisted with ultrasound (15 min) and by stirring (with magnetic stirrer for 1 h) was also compared. Results showed that addition of APP increased cooking loss and the amount of absorbed water of the pasta samples. Hardness and adhesiveness of pasta samples was decreased with APP addition. Pasta with added APP had significant higher levels of TPC and AOA compared with pasta without addition of APP. The highest TPC (1.4 g of gallic acid equivalents/kg) was in raw pasta with addition of 15% APP from which phenolics were extracted with ultrasound assisted extraction and methanol. Regarding AOA, the highest antioxidant activity (0.8 mg gallic acid equivalents/100g) was also in raw pasta with 15% APP, from which phenolics were extracted by stirring and ethanol. In cooked pasta, the levels of TPC and AOA, were significantly lower compared to raw pasta (p≤0.05). Sensory evaluation showed that there was no significant difference between DS and DS + 10% APP. Apple peel powder (APP) could be a food by-product, conveniently used as additive, for delivering health-promoting bioactive compounds such as polyphenols

Accumulation of Amadori and Maillard Products in Wheat Seeds Aged under Different Storage Conditions

Occurrence of protein modification by Amadori and Maillard reactions in wheat seeds during ageing at different temperatures and relative humidities (RH) has been investigated over 12 month period. Spectrofluorimetric determination of Maillard products of partially purified proteins extracted from aged seeds revealed increase of protein fluorescence at 325/425 nm (excitation/emission wavelength). The highest increase of Maillard products was observed for seeds aged at 40 °C, RH = 45 %, followed by storage at 25 °C, RH = 45 % and storage at warehouse conditions (10–30 °C, RH = 40–70 %), while seeds kept at 4 °C, RH = 40 % did not show significant accumulation of Maillard products. Similar pattern of accumulation were observed for Amadori products, except for seeds aged at 40 °C, RH = 45 %, where products decreased after 270 days of storage. Obtained data indicate that a wheat seed ageing during storage is associated with protein modification by Amadori and Maillard reactions. However, the contribution of these reactions varies under different storage conditions

Quality Parameter Changes in Wheat Varieties During Storage at Four Different Storage Conditions

Changes in seed quality parameter of three wheat varieties during one year storage at four different storage conditions, were studied. Applied storage conditions adversely affected quality changes in wheat seeds during one year storage. The most pronounced changes were observed for seeds kept at 40°C, RH = 45%, followed by seeds stored at 25°C, RH = 45%, while seeds kept at 4°C, RH = 45% or at warehouse conditions mostly showed minimal or statistically insignificant changes. Elevated temperature of seed storage caused a significant decrease of starch content, hectoliter weight, and wet gluten content, accompanied with increase in fl our acidity, and fluctuating in Zeleny sedimentation value. The intensities of observed changes showed strong dependence on wheat variety

Količina soli u hrvatskim pekarskim proizvodima

Visoki krvni tlak je glavni uzročni čimbenik srčanih bolesti i moždanog udara, koji može biti uspješno smanjen redukcijom unosa natrija (preko kuhinjske soli) u prehrani. Unos soli za stanovništvo diljem Europe, pa tako i Hrvatske, je visok i premašuje količine potrebne za normalno funkcioniranje. Prosječan unos soli u svijetu iznosi oko 10-13 g/dan, a u Hrvatskoj i više. Preporuke svjetske zdravstvene organizacije su 5-6 g/dan

Textural characteristics of ready-to-eat breakfast cereals produced from different types of cereal and with varying water addition during extrusion process

U radu je ispitan utjecaj dodatka pšeničnog, kukuruznog i rižinog brašna te različite količine dodane vode (21 %, 23 % i 27 %) u procesu ekstruzije na strukturu ekstrudiranih žitarica za doručak. Uzorci su pripremljeni sa i bez slatkog premaza. Teksturalna svojstva suhih ekstrudiranih kuglica i kuglica pripremljenih kao obrok s mlijekom ispitana su pomoću senzorskih metoda i instrumentalno pomoću analizatora teksture TA.XT Plus. Weibullova jednadžba se koristila za nelinearnu regresijsku analizu eksperimentalnih podataka za apsorpciju mlijeka i promjenu hrskavosti u pripremljenom obroku tijekom vremena. Hrskavost suhih ekstrudiranih uzoraka bez premaza je bila mnogo veća od hrskavosti uzoraka s premazom. Najveću hrskavost imali su uzorci od čiste pšenične krupice i brašna, a najmanju, uzorci od mješavine pšenične krupice i kukuruznog brašna. Povećanjem količine dodane vode u procesu ekstruzije smanjivala se hrskavost gotovog proizvoda. Sposobnost apsorpcije mlijeka i gubitak hrskavosti u obroku s mlijekom bili su mnogo jače izraženi i brži kod uzoraka bez premaza u odnosu na uzorke s premazom.Textural characteristics of ready-to-eat breakfast cereals were evaluated in order to determine the influence of wheat, corn and rice flour, as well as a varying water addition during the extrusion process. Extruded breakfast cereal balls were made of wheat semolina in combination with wheat, corn or rice flour. Three different levels of water addition (21 %, 23 % and 27 %) were used during the extrusion process. Samples were prepared with and without surface sugar coating. Sensory and instrumental assessments (TA.XT Plus) were used to evaluate textural attributes of dry samples and samples during immersion in milk. Weibull equation was used for nonlinear estimation of experimental data obtained for milk absorption and crispiness as a function of time. Crispiness of dry extruded balls without coating was much higher than for samples with coating. The highest values for crispness were observed for wheat extruded balls and the lowest for samples with corn flour addition. Increasing water addition during the extrusion process significantly increased crispness of ready-to-eat breakfast cereals. The rate of milk absorption and loss of crispiness were significantly higher for samples without coating than for samples with coating

UTJECAJ TEMPERATURE I RELATIVNE VLAŽNOSTI ZRAKA NA UDIO VLAGE U SJEMENU, KLIJAVOST I ENERGIJU KLIJANJA TRIJU SORTI PŠENICE TIJEKOM JEDNOGODIŠNJEGA SKLADIŠTENJA

Changes in grain moisture, germination and vigour of three wheat cultivars packed in paper bags and stored for one year under four different conditions of environmental temperature and relative humidity (RH) were investigated. During the first ninety days of storage significant reduction in grain moisture content of 4, 2.5 and 0.9 %, respectively, under 40 °C, 25 °C and 4 °C and RH of 45 % occurred. Subsequently grain moisture remained constant until the end of storage. Seeds of examined cultivars lost their germination ability and vigour only under elevated storage temperatures. Germination and vigour loss after one year of storage differed between cultivars being higher for seeds kept under 40°C, RH = 45% (35-85 % and 55-94 %, respectively), than under 25°C, RH = 45 % (10-20 % and 15-22 %, respectively). Obtained data indicate significant influence of storage conditions on moisture content, germination and vigour changes during storage of wheat seeds, as well as varietal dependence of seed viability.Cilj ovoga rada bio je ispitati utjecaj četiri različita uvjeta temperature i relativne vlažnosti zraka (RH) na promjene vlažnosti sjemena, klijavost i energiju klijanja triju sorti pšenice pakirane u papirnate vrećice i skladištene godinu dana. Tijekom prvih 90 dana skladištenja nastupilo je značajno sniženje vlažnosti sjemena od 4, 2,5 i 0,9 %, pri uvjetima skladištenja od 40 °C, 25 °C i 4 °C pri 45% RH, nakon čega je sjeme zadržalo vlažnost na istoj razini sve do kraja skladištenja. Gubitak klijavosti i energije klijanja nastupio je samo pri višim temperaturama skladištenja i razlikovao se među sortama. Nakon godinu dana skladištenja, gubitak klijavosti i energije klijanja bio je veći kod sjemena skladištenoga pri 40 °C (35-85 % i 55-94 %), nego pri 25°C i 45 % RH (10-20 % i 15-22 %). Podaci istraživanja ukazuju na značajan utjecaj temperature i relativne vlažnosti zraka na promjene vlažnosti sjemena, klijavost i energiju klijanja ispitivanih sorti tijekom skladištenja, kao i na značajnu ovisnost promjena klijavosti i energije klijanja o sortnim karakteristikama