Effects Of Baking Temperature, Time And Humidity On Bread Crust And Crumb Properties

The main objectives of this study are to investigate the effects of baking temperature, time and humidity on bread qualities and subsequently find the relationship between bread crust and crumb properties. The bread samples were prepared following the straight-dough method. In determining crust and crumb, the difference in colour between these two regions was used. The colour of crust and crumb were measured using a chromameter. The colour range obtained for crust based on top crust colour of commercial bread samples is L 2.4 and b >22.3 while crumb has a range of L >66.0, a <2.4 and b< 22.3. This colour range is used as a guideline in determining crust thickness of baked loaf samples. Bread slices were scanned to obtain its L a b values and the crust thickness was determined from the crumb region when the L a b values are met. The evaluation of crumb moisture content and firmness were conducted following the standard method of American Association of Cereal Chemist (AACC) 14-5A and American Institute of Baking (AIB), respectively. Experimental results were statistically analyzed using Analysis of Variance (ANOVA). Various combination of baking temperature, time and humidity affected the organoleptic properties of bread. Baking temperature and time significantly affect bread crust colour (P<0.001), thickness (P<0.001), initial moisture content (P<0.05) and firmness (P<0.001). Baking temperature has larger effect on crust colour and thickness compared to baking time. Higher baking temperature produced darker and thicker crust. Rate of thickness increment was also higher at high baking temperature (0.0465 mm/min) compared to low baking temperature (0.0085 mm/min). Increasing baking temperature produces crumb of high initial moisture content with high firmness value. The effect of baking time (P<0.01) is less significant than temperature however increasing baking time would also darken the crust colour and increases the thickness, increases crumb firmness and reduces crumb moisture content. The application of humidified baking has no significant impact on crust coloration (P>0.05) however it causes a decrease in crust thickness (P<0.05), retain moisture (P<0.01) and reduce firmness (P<0.05). Humidified baking also reduces moisture migration (P<0.01) and firming rate (P<0.01) of breads during storage. Besides humidified baking, the usage of baking lid also have potential in increasing L and b values (P<0.001) and reducing a value and crust thickness (P<0.001). However, the application of lid prevents bread expansion and causes high firmness value in bread. Sandwich bread has lower moisture content compared to open bread. Three important correlations were obtained from the study that are between top crust colour difference (ΔE) and thickness, ΔE and firmness and finally crust thickness and firmness. The correlation between ΔE and thickness for non-humidified (NH) baking is represented by yNH = 0.1724x and yH = 0.1712x for humidified (H) baking. The coefficient of correlation, R2, for correlation between ΔE and thickness for non-humidified baking and humidified baking are given by 0.9467 and 0.9341, respectively. A simple model of T = kΔE derived from the correlation between ΔE and thickness indicates that the crust thickness (T) can be predicted by the changes in crust colour (ΔE). The heating constant, k, is dependant of baking temperature. The correlation, ΔE and firmness has the R2 of 0.8306 for non-humidified baking and 0.8025 for humidified baking. The correlation between ΔE and firmness for non-humidified baking is represented by yNH = 0.8375x + 20.824 and yH = 0.8127x + 25.035 for humidified baking. The other correlation, thickness and firmness has the R2 of 0.7436 and 0.6915, for non-humidified and humidified baking, respectively. The correlation of thickness and firmness for non-humidified baking is represented by yNH = 4.0385x + 26.952 and yH = 3.921x + 30.852 for humidified baking. The high value of R2 shows that there is a strong relationship between colour, thickness and firmness. Crust colour can be used in predicting crust thickness and crumb firmness In conclusion, the results show that the bread crust and crumb properties are highly dependent of baking temperature and time. The moisture content and firmness in crumb are also affected by crust formation. This research also produces several significant contributions for bakery study; new method of measuring crust thickness using colour, humidified baking application for improving the storage quality of bread and finally establishment of correlations and linear model that can be used to estimate crust thickness and probably anticipate crumb behavior during storage

Bread crust thickness estimation using L a b colour system

The crust formation of bread is imperative as it contributes to aroma, flavour and texture of the product. The extent of surface browning during formation of crust is suspected to correspond to the thickness of crust and gradually affects the quality of the bread produced. A method to distinguish the crust and crumb was developed using the L a b colour system. Commercial breads of different categories, sandwich, open and standing breads, were used as samples to set up the colour range for crust and crumb. In general, L is always higher in the crumb compared to crust. However, a and b values in crust are consistently higher than crumb which indicates the browning effect. The xE between crust and crumb in sandwich, open and standing breads were 30.98, 29.86 and 25.96, respectively. Bread crust is identified as the brown region with L value lower than 66, a value higher than 2.4 and b value higher than 22.3. Baking temperatures in the range of 175 to 200°C and baking times from 30 to 50 minutes were used to bake open loaves with different crust colours and thickness. Higher baking temperature and time are proven to produce bread with intense surface colour and thicker crust. The correlation between crust colour and its thickness shows good linear relationships indicating the possibility of predicting crust thickness using its surface colour

Impact of humidified baking on crust and crumb properties of open bread during storage

Humidified baking was investigated in the light of producing breads envisaged to have better quality and freshness. Open bread loaves were prepared using the straight dough method where baking was performed with or without humidity at three levels of temperatures of 185, 195 and 205°C, and baking times of 25, 30 and 35 min. Baked breads were evaluated by measuring its crust color and thickness, and bread crumb moisture content and firmness. Humidified baking has no significant effect in enlightening bread crust color (P > 0.05) but significantly reduced the crust thickness (P < 0.001) and increased the initial moisture content (IMC) of bread crumb. The higher IMC of bread crumb led to a higher final moisture content (FMC) of bread during storage and these helped to reduce the firming rate of bread during a 96 h storage especially for the lower baking temperatures and times. Significant differences (P < 0.001) were observed on crust color and thickness, and bread crumb moisture content and firmness as effect of baking temperature and time

Effect of particle size on the explosive characteristics of grain (wheat) starch in a closed cylindrical vessel

Wheat starch dust explosion poses a serious threat to food processing and handling industries. This study attempts to show the influence of particle size on some explosive characteristics of wheat starch dust. The maximum pressure, maximum rate of pressure rises, and severity factor index were determined in relation to four different particle sizes of wheat starch dust of 38 µm, 45 µm, 53 µm and 71 µm using the 1.2 L Hartmann explosion tube. The result of proximate and elemental analysis conducted showed the sample has a moisture content of 2.1 %, volatile content of 93.3 % and a calorific value of 15,777.2 J/g. The carbon content of the sample was 40 % and the hydrogen content 6.9 %. The result of the explosive parameter tests showed that the maximum explosion pressure of the wheat starch dust sample increased with decreasing particle size with the highest recorded value of 735 kPa for the particle size of 38 µm

Bread crust thickness measurement using digital imaging and L a b colour system

A simple and new method was developed for the evaluation of baking process on bread quality through the measurement of bread crust thickness. By distinguishing the crust and crumb regions of bread, the system which uses digital imaging and the L a b colour system can predict bread crust thickness from the colour measurements of bread surface browning. Standard baking tests were conducted at different levels of temperature and time combinations to produce open breads with different crust thickness. The results show that the crust thickness which ranged from 6.02 to 9.00 mm has a negative relationship with each of the L, a, and b values and a positive correlation with the total colour difference (ΔE) of bread crust. The data also demonstrated that crust thickness increases with the investigated baking temperatures of 185, 195, and 205 °C more significantly (p < 0.0001) than baking times of 25, 30 and 35 min (p < 0.001)

Multivariate data analysis of pesticide residue on spinach leaves based on ft-ir spectroscopy

Vegetables are susceptible to diseases and pest attack; hence pesticides are widely used by farmers to avoid or reduce pests. The use of pesticides may leave some residues on the vegetables after harvesting and not safe for consumption. Thus, it is essential to monitor the levels and concentrations of pesticide residues in vegetables. Currently, gas chromatography and high-performance liquid chromatography are used as a method for detecting the components of pesticide residues in vegetables. However, these methods are destructive and often time consuming. Therefore, in this study, Fourier transform infrared (FT-IR) spectroscopy combined with multivariate data analysis was selected as a rapid, non-destructive method to obtain spectral information from pesticide residues. Spinach leaves were sprayed with malathion followed by washing treatments. The results showed that washed and non-washed samples can be clearly distinguished, with non-washed samples showing a high absorbance intensity at 970 cm-1 which belongs to the ester functional group that can be used to determine malathion. This approach can be further developed as a routine analysis tool for quantification of the safe range of pesticide residue concentrations in vegetables

Effect of solvent pH, microwave power and extraction time on microwave-assisted extraction of Hibiscus rosa-sinensis

The objectives of the study were to evaluate the effect of solvent extraction pH, microwave extraction power and time on the yield of total anthocyanin and colour of Hibiscus rosa-sinensis (H. rosa-sinensis) extract and to evaluate the storage stability of total anthocyanin content and antioxidant activity of these extracts during storage. The factors studied were solvent pH (1.0 and 4.0), microwave power (400 W and 800 W) and extraction time (1 min and 3 min). Results showed that the highest total anthocyanin extracted was 9.56 ±0.001 g cyanidin-3-glucoside when extraction was performed using solvent of pH 4 at 800 W and 3 min and followed by 8.33 ± 0.001 g cyanidn-3-glucoside using solvent of pH 2 at 800 W and 3 min. H. rosa-sinensis extract in pH 2 was in red while the extract in pH 4 was in dark red. For the 10 d storage stability analysis, H. rosa-sinensis extract of pH 2 and pH 4 at 800 W and 3 min were selected. During storage, the extract in pH 4 showed an increase in total anthocyanin content and radical scavenging inhibition percentage. On contrary, the total anthocyanin content and radical inhibition percentage for pH 2 extraction sample decreased during storage

Effect of microwave drying technique on the properties of dried rice food

Drying methods are critical determinant in the preparation of dried food because each parameter plays important role in achieving the desired quality. The objective of this study was to investigate the effect of drying conditions of combined oven and microwave drying on the properties of rice-based ready-to-eat dried food. Cooked rice sample (with different ratio of white rice and glutinous rice) was dried by oven at 90°C for 130 min and followed by drying in microwave at various power level (450 and750 W) and time (1, 3 and 5 min). Moisture content and color of the dried rice sample were deter-mined after drying in microwave. The results showed that the dried rice sample using glutinous rice formulation contained the highest moisture content. Moisture content of dried rice decreased with the increase of drying time in microwave. Color analysis shows that mixed white rice and glutinous rice gave the best result of hue angle and chroma value. From this study, it can be concluded that microwave drying technology is a modern technique that can be used for drying of food to extend the shelf-life of food product and shorten the processing time

Optimization of the antioxidant-rich xanthone extract from mangosteen (Garcinia mangostana L.) pericarp via microwave-assisted extraction

Total phenolic content (TPC) and antioxidant properties of xanthone extract from mangosteen pericarp via microwave-assisted extraction (MAE) method was optimized by response surface methodology (RSM). The MAE extraction conditions to obtain optimum antioxidant-rich xanthone extract were at 2.24 min of irradiation time, 25 mL/g of solvent-to-solid ratio and 71% of ethanol concentration. The predicted results for four responses were as follows; 320.31 mg gallic acid equivalent/g extract, 83.63% and 93.77% inhibition (DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-Azino-bis-3-ethylbenzthiazoline-6-sulfonic acid) assays), and 144.56 mg Trolox equivalent/g extract (FRAP, Ferric reducing antioxidant power). The predicted and actual values were statistically insignificant (P > 0.05). Therefore, these results confirmed that the examined model was acceptable and relevant. MAE led to a slightly similar antioxidant capacity and a higher extraction of α-mangostin, a major xanthone of mangosteen pericarp as compared to water bath-maceration technique

Effect of Ultrasonic Amplitude on the Yield and Properties of Barramundi (Lates calcarifer) Skin Collagen

Barramundi skin, a by-product of the fish processing industry, has shown potential as an alternative collagen source. However, the commonly used acid extraction method to produce collagen rendered a low yield requires a lengthy time and is not environmentally friendly. As a result, the adoption of greener technology, such as ultrasound, to improve the conventional extraction process is emerging. This study aimed to investigate the effect of different ultrasonication amplitudes on collagen recovery from barramundi skin. The resulting collagens were evaluated for their protein, hydroxyproline and moisture content, colour, molecular weight distribution, and FTIR spectra. Ultrasound-assisted extraction (UAE) was performed at 40 (UAE40), 60 (UAE60) and 80 (UAE80) % amplitude for 20 min. For comparison, acetic acid extraction was also carried out to produce acid-soluble collagen (ASC). UAE increased the yield (p<0.05) of collagen from barramundi skin, with UAE80 exhibiting a 7-fold increment compared to ASC. Increasing the ultrasonic amplitude increased the yield considerably but decreased the hydroxyproline content, indicating a reduction in collagen quality. Furthermore, the protein content and SDS-PAGE profile of the extracted collagens revealed that UAE promoted protein degradation. FTIR spectra indicated that despite slightly varying wavenumbers, no detrimental effect on the triple helical structure was seen following UAE with the presence of amides A, B, I, II, and III. Also, the α1, α2 and ß-chains were found in all samples, although the band intensity reduced as the amplitude increased. In conclusion, given the right conditions, UAE could improve the extraction yield without influencing the collagen structure