Introduction

Cakes are popular and frequently consumed by almost all levels of society for their desirable sensory properties and convenience. They differentiate mainly by their porous structure and high moisture content from the commonly consumed baked products such as bread, biscuits, etc. Muffins belong to the greasy cakes group rather than foam-type cakes and prepared as individual-sized portions that are smaller than cakes with no need to cut into slices. They are obtained by preparing a batter from wheat flour, sugar, oil, egg, milk and aroma products ^{1, 2}. The current market trend for muffins is increasing in parallel to the interest in customizable bakery, though consumers highly expect affordable and healthier options at the same time.

Overall cake quality is mostly related to volume besides a flexible, smooth and soft texture ³. Moreover, generally cakes enable the corporation of different ingredients into their formulations⁴ when one or more sources of dietary fibres are added^5-9.Attempts for use of dietary fibre in food products have both health and nutrition standpoints¹⁰. Dietary fibres are composed of various complex compounds such as polysaccharides, oligosaccharides, lignins found in plants that cannot be digested like other nutrients. Recent studies revealed that certain diseases defined as “diseases of the civilization (constipation, haemorrhoids, large bowel cancer, obesity)” were related to the lack of dietary fibre consumption. . Moreover, dietary fibre has been proven to be effective on myocardial infarction, fatal coronary heart disease, some types of cancer, weight gain, diabetes, insulin resistance and metabolic syndrome ¹¹.

Although different dietary fibres have been used in numerous studies, use of different dietary fibres as combinations was only investigated in products such as extruded breakfast products¹²and psyllium, oat flour and inulin in pasta^{13, 14}. Oat (Avena sativa) is a very common cereal having positive health effects on serum cholesterol such as attenuation of blood glucose with its soluble fibre β-glucan. Oat flour and/or fibre has been used in numerous studies as a dietary fibre source for cakes or muffins^15-18. Quinoa is a pseudocereal having  high nutritional value with higher amounts of vitamins and minerals in comparison to most cereals, protein (13–14%) and dietary fibre¹⁷. It has been used commonly in bakery products and particularly gluten-free formulations ^19-22. Although it has distinct advantages in terms of its nutritional properties, the use of quinoa flour in combination with oat flour has been proposed as a method for improving functionality ¹⁷. Dateseeds although slightly differing among different date varieties, is richer in protein and fat in comparison to date flesh, being also a very rich source of dietary fibre (73.1 g/100 g), phenolics and antioxidants ²³. In a previous study, wheat flour has been substituted by date seed flour and date seed hydrolysates in muffin formulations and physicochemical effects have been investigated⁵.

Although some studies evaluated the effects of individual uses of different types of fibres in muffins ^{15, 16, 38, 39}, the studies on the combined soluble and insoluble fibre usage is limited, Therefore, this study aims to fill in the gap in literature by evaluating either individual or combined usage of different uncommon such as date seed flour, quinoa flour and oat bran flours with dietary fibre in muffins by emphasizing the changes in their quality.

Materials and Methods

The Preparation of Muffins

Date seed flour, oat bran, and quinoa are used as different sources of dietary fibres. Fibres were used as flour substitutes (10%, w/w) and used both single and dual combinations. Muffin preparation was made according to the method by Ambigaipal and Shahidi (2015). Milk, sugar, eggs, oil and baking powder (purchased from a local market in Istanbul, Turkey) were mixed and baked in baking cups with a diameter of 10 cm and each of the muffin samples weighed about 35 g before baking. For each formulation, a total of3muffins were baked and the production was performed twice. Wheat flour (Sinangil Flour, Turkey), Oat (Ada Sultan, Turkey), quinoa (Dimyat Gold, Turkey) were obtained from a local market and quinoa was in a laboratory mill (IKA Gmbh, Germany)to pass through 214 μm sieve  as flour. The details of muffin formulations are given in Tables 1.a and 1.b.

Baked cakes were cooled down to room temperature and then stored in zipped plastic bags and a portion of ground samples were stored at -18ºC until analysis.

Table 1(a): Muffin Formulations.

Table 1(b): Muffin Sample Combinations.

Proximate Analyses

Total moisture, ash and protein determination tests were performed using AOAC methods 925.10, 923.03 and 920.87, respectively ²⁵.

Total Dietary Fibre

Total amount of dietary fibre was measured using the total Dietary Fibre Assay Kit (TDF-100; Sigma-Aldrich, USA) based on AOAC Method 960.52 enzymatic-gravimetric method.

Muffin Quality Evaluation

Muffins were left for about 1.5 hours at room conditions for cooling after baking and then total volume was measured by the rapeseed displacement method number 10-05 of AACC International ²⁶. Specific volumes were calculated by diving the muffin volume values to their weight (ml/g). Weight loss in muffins was measured using the below formula;

W_i is the muffin batter weight before baking (g), whereas W_F is the final weight of the muffin sample after cooling.

Top height of the muffins were measured with a calliper, in mm.

Texture Profile Analysis (TPA)

TPA of the muffins (cut from the centre ) were measured using the texture analyser (Stable Micro Systems TA-XT Plus, Godalming, Surrey, UK) with the aluminium cylinder probe (35 mm in diameter) and parameters of 50 N maximum load, 55 mm/minutes of pre-test speed and test speed of 120 mm/min. (2 mm/s) and 25% compression ratio, according to the AACC Method Number 74-09 Hardness (N), were from the Texture Profile Analysis (TPA) graph. Measurements were made on the day after baking in two replicates.

Colour

Colour density (L*, a*, b*) measurements were made using Chromameter (CR-400, Konica Minolta Holdings Inc., Tokyo, Japan) in cakes in slices of 2.5 cm width. All measurements were made at three different points.) Colour change was calculated using the following formula.

In the equation L_o, a_o and b_o values belong to the control muffin and were taken as reference values.

Statistical Analysis

Differences among muffin formulations using the factors of fibre sources (3 types) and their condition of combination (2 types) were assessed by One Way Analysis of Variance (ANOVA) using the SPSS statistics software (version 10.0) at 95% level of significance. Further post-hoc tests were conducted using the Duncan’s Multiple Range Test and Pearson correlation coefficients between characteristics (p<0.01 and p<0.05) were calculated using the same software.

Results and Discussion

Proximate Analyses of Raw Materials

Compositions of flours used as raw materials in the study were given in Table 2.

Total moisture and ash contents of flours with dietary fibre differed between 6.2 and 8.6% and 1.09-3.23 %, respectively. Dietary fibre constituents were different for all samples. Although soluble fibre contents are quite similar in flour samples, insoluble fibre content and total fibre content changed as follows: date seed flour>oat bran flour>quinoa>wheat flour. Date seeds have been reported to have high dietary fibre content by different researchers such as 73.1g/100g²³ or 76.58 g/100 g dry weight ²⁷similar to the present results. The insoluble fibre content has also been reported as 67.26 g/100 g dry weight previously²⁷. has been shown to have 8.1% moisture and 13.5 % protein contents, previously ²⁸. Different wheat flour sources (wheat flour, cake flour, multi-purpose flour, whole grain wheat flour etc.) have been used in cake, cupcake and muffin studies. According to these sources present wheat flour was similar to the previous reports in literature with the moisture and ash³⁷ or had slightly lower moisture and higher protein (wheat flour moisture 14%, protein 9.8%) ^8. Cake flour used in another study¹⁷ has 0.65% ash and 13.5% moisture. Oat bran proximate composition has been reported to be affected by the variety, cultivation conditions and extent of the milling process applied during the processing, change from 15%–18% for protein and  10%–40% total dietary fibers⁴¹. While total fibre content is parallel to previous findings (24.4%), total protein content in present study (10.4%) seemed to be lower than the previous literature and thought to be affected by the dry milling conditions of the oat bran.

Table 2: Proximate Analyses of Ingredients.

Values ​​in the table represent mean values ​​and standard deviation of 2 replicates

Different letters in each column shows that there is a statistically significant difference between the samples (p< 0.05)

Proximate Composition of Muffin Samples

Proximate composition of muffin samples were given in Table 3. Dietary fibres affected the moisture contents of muffin samples significantly (28.2-31.2%) (p<0.05). Only Q samples had similar moisture levels with control samples while DQ samples were slightly higher in the moisture measured (p<0.05). Remaining muffin samples had significantly lower levels of moisture (p<0.05). According to literature, addition of date flour ⁵ and cocoa fibre³¹  had a slightly increasing effect on moisture in comparison to control muffins. Quinoa flour and whole oat flour also have been reported to have a moderately high level of water absorption properties ¹⁷. In cookies with quinoa and chia flour, in contrast, moisture levels were lower than control samples and this was suggested to be related with the higher moisture retention capacity by quinoa and chia flour ²².

Table 3: Proximate Analyses of Muffin Samples.

Values ​​in the table represent mean values ​​and standard deviation of 2 replicates

Different letters in each column shows that there is a statistically significant difference between the samples (p< 0.05).

Difference among the ash contents of the muffin samples was statistically insignificant as neither individual nor combined addition of fibre sources had a significant effect on the ash contents (p>0.05). In literature, ash contents have been reported to be increased with date flour addition into muffin samples, ranging from 1.12% to1.15% (d.b.) depending on the level of substitution level of wheat flour (2.5 or 5%)⁵.

Among the measured protein contents of the samples (changing from 8.12% to 13.53%) differing significantly (p<0.05), only QO samples had the protein content as high as the control sample. In parallel to present results, research have revealed that combination of two or more food materials (eg. cereals and legumes) increased nutritional properties of the final food products⁴⁰.

Dietary fibre contents of the muffin samples increased significantly after use of different fibre sources, in comparison to control (p<0.05), the only exception was quinoa flour. The measured amount of fibre changed from 1.2 % in control samples to 10.4% in DQ samples. Combined use of fibre sources gave slightly higher fibre contents than their individual usages.

Previous literature revealed that, fibre sources with high insoluble fibre contents ended up with a higher dietary fibre content in the end product when they were used either with in gluten-free formulations ²⁴. This also supported our results as the highest fibre contents were measured in muffin combinations comprising date seed flour (DQ and DO). These results might be related with the highest amount of insoluble fibre content it has, among all ingredients. Changes observed in the measured fibre from the fibre containing flour as raw ingredient to muffin samples, might be related with the effect of heat, as it has been reported as a factor that might change soluble to insoluble fibre ratio and also the measured total dietary fibre content. Particularly, observed increase in fibre content is attributed to the formation of fibre-protein complexes that are heat resistant and are collected as fibre ²⁹.

Quality of Muffin Samples

Overall quality parameters of the muffin samples were depicted in Table 4. Weight or weight loss measurements of the samples were not significantly different than each other (p>0.05), this findings were in parallel to the literature findings which found no differences in weight measurements in different fibres incorporated cakes ³⁰.Weight loss is generally related with the water loss of cake systems. Therefore, the dietary fibre sources acted as successful water loss barriers for the muffins. Volumes of muffin samples decreased significantly (p<0.05) for all samples except for QO after fibre source addition.

Table 4: Muffin Quality Properties.

Control: Control muffin, no flour substitution; D: 10% date seed flour substitution; Q: 10% substitution with quinoa flour, O: 10% substitution with oat bran flour; DQ: 5% date seed flour and 5% quinoa flour substitution; DO: 5% date seed flour and 5% oat bran flour substitution: QO: 5% quinoa flour and 5% oat bran flour substitution

Different letters in each column in same colour shows that there is a statistically significant difference between the samples (p> 0.05).

In literature similar various trends have been investigated after fibre addition ^{9, 16}.

Generally, fibre addition has also been reported as a factor to decrease the volumes in cakes and explained generally as a disorganization of starch-gluten network ³¹. It is known that during baking, expansion of air bubbles entrapped in the batter matrix due to the temperature increase and chemical leavening is the basic mechanism under the measured cake volume. Moreover, coalescence, protein denaturation, and starch gelatinization also affects cake structure ²⁴. In contrast, there are some findings that found oat fibre addition improved the volumes of layer cakes ³⁰. Therefore type of fibre is a significant factor for volume measurements¹⁶. Differences in muffin formulations have been reported to be more effective on muffin volume and density due to the increase in batter viscosity and high water binding capacity of fibres, while muffin diameter and weight loss were less affected⁸. Oat fibre is a source of insoluble fibres that contained cellulose, hemicellulose, and lignin. In another study, gluten-free layer cakes, the highest cake volume was obtained when the inulin and oat used in combination and it has been suggested that the collapsed structure may have been strengthened by the oat flour ²⁴.  Therefore, similar effect was seen in QO samples, to sustain a better volume in comparison to all other treatments to give similar volume properties to control muffins. The specific volume mainly has been proposed to be related with the extent swelling of the muffin dough ³².

Specific volumes of the muffins changed significantly between 1.94 and 2.88 ml/g) (p<0.05). Only in QO and D samples, specific volume was measured as being similar to that of control samples. Quinoa flour substitutions have been shown to increase the specific volumes / volumes of gluten-free bread samples, in previous studies^{19, 20}. Volume and specific volume measurements correlated very well (0.938) (shown in Table 5) as the weight differences are insignificant, similar to previous studies ³⁰. According to another study, specific volume values similar to control samples were measured only in lower level of (5%) pea and oat fibre incorporated cake samples ¹⁵. In some literature sources dietary fibre addition has been interrelated with the increased softness in cake crumbs to result in a negative correlation with the specific volume, by dietary allowing more amount of water into the cake structure ⁸. However, this finding was not detected in this present study.

The height of the muffin samples changed between 13.6 and 18.6 mm. The maximum height was measured in dateseed added muffin (D).  Quinoa and oat flour seemed to make a decreasing effect on the muffing heights. The height of the muffins significantly correlated negatively with hardness (-0.757) and chewiness (-0.809). In literature the height of the muffins is a significant indicator to depict thew muffin quality and generally fibre usage has been reported to affect the dough structure, by causing a decrease in level of CO₂ retention³⁸.  having a negative influence on CO₂ retention.

Textural parameters of muffin samples are shown in Table 5. Hardness of muffin samples changed between 0.6 and 2.9 N, difference among them being significant (p<0.05). The hardest sample was QO sample (2.9 N). Increase in hardness after fibre source incorporation to cakes is in parallel to the previous findings using oat fibre in literature ²⁴. Previously, increase in hardness has been linked to the differences in the water binding capacities of fibre sources used. For example, if the water binding capacity of the fibre is high, wheat flour could not find the necessary amount of water to develop the gluten-protein network, and therefore the product becomes rigid to give higher hardness ^{15, 33}.

Table 5: Muffin TPA.

Control: Control muffin, no flour substitution; D: 10% date seed flour substitution; Q: 10% substitution with quinoa flour, O: 10% substitution with oat bran flour; DQ: 5%date seed flour and 5% quinoa flour substitution; DO: 5%date seed flour and 5% oat bran flour substitution: QO: 5%quinoa flour and 5%oat bran flour substitution

Values ​​in the table represent mean values ​​and standard deviation of 2 replicates

Different letters in each column shows that there is a statistically significant difference between the samples (p< 0.05).

Interestingly, increased hardness was not evident for D and DQ samples andtheir hardness levels (0.6 N) were not significantly different from the control sample (0.7 N) (p>0.05).This effect may be explained with these fibre sources allowing more free water to be available in the muffins⁶. D samples had also statistically similar specific volume values with control samples. Parallel trend  between specific volume and hardness was evident in previous studies, as well ¹⁵. Almost all samples (except DO and QO) had been statistically similar to control muffins for cohesiveness. This attribute was also positive, since generally the low cohesiveness has been attributed to the crumbling property ²⁸.  For DQ muffins, specific volumes were slightly lower, although their higher moisture in comparison to all other samples, might be related with their lower hardness.

Generally, increase in hardness and cohesiveness together with decreased resilience has been reported ^{24, 34}. In the present study, hardness was found to correlate significantly with cohesiveness (-0,691) and chewiness (0.634) (p<0.01) (correlation data given in Table 6). However, no significant correlation was detected between hardness and resilience (p>0.01). Only for those samples that are significantly harder and less resilient (DO and QO), a statistically significant decrease in cohesiveness was evident. It has been reported that this decrease might be linked to the loss of intermolecular interaction among ingredients³⁵. Dateseed flour and oat bran flour have the highest amount of insoluble fibre contents, therefore their use in combination might have been effective on those properties as these have been mainly attributed to the insoluble fibre in previous studies²⁴. Chewiness is not primary, but a secondary texture parameter measuring the extent of difficulty in chewing and it is generally parallel to hardness. Resilience and springiness are significant parameters for muffin quality to depict the degree to which the sample recovers after compression³⁴.

DQ sample were the best combination of fibres among muffins, with statistically no change in hardness, cohesiveness and springiness. In addition, those samples were significantly less chewy in comparison to control samples.

Correlation Coefficients between the Quality Parameters of Muffin Samples.

Table 6: Correlation Coefficients between the Quality Parameters of Muffin Samples.

Spring: Springiness; Cohes: Cohesiveness; Chew: Chewiness; Resil: Resilience

**. Correlation is significant at the 0.01 level (2-tailed).

*. Correlation is significant at the 0.05 level (2-tailed).

Colour

Crust colour measurements of samples (taking the control sample (C) as reference) are summarized in Table 7.

Table 7: Colour Measurements of Muffin Samples.

Control: Control muffin, no flour substitution; D: 10% date seed flour substitution; Q: 10% substitution with quinoa flour, O: 10% substitution with oat bran flour; DQ: 5% date seed flour and 5% quinoa flour substitution; DO: 5% date seed flour and 5% oat bran flour substitution: QO: 5% quinoa flour and 5% oat bran flour substitution

Different letters in each column in same colour shows that there is a statistically significant difference between the samples (p> 0.05).

Crust colour parameters of muffin samples differ significantly (p<0.05). in bakery products is mostly affected by the Maillard reactions, but dietary fibre substitutions are not at that extend to affect quantity of sugars and amino acids. However, possible colour changes were proposed to be related with the changes in pH, where fibre was acting as a buffer that changes the water availability to give those reactions ³⁰.  In the crust, lightness (L*) value was significantly lower than the control samples, only in dateseed flour incorporated sample (D, DO and DQ), even at lower levels of substitution (5%) as used in fibre combination treatments. Redness parameter (a*) was also significantly different for only date seed flour substituted samples. Significant change in colour parameters of muffins after date seed flour incorporation was also stated by the previous studies ^{5, 36}. Q, O and QO muffins were statistically similar to control samples in yellowness (b*) (p>0.05). Dateseed flour on the other hand, decreased the yellowness significantly either individual or in pairs (p<0.05). In Q, O and QO samples, total colour change was very low in comparison to D containing samples. The original colour of the fibre source has a significant effect on the colour of cereal product produced ^{8, 34, 36}. In crumb, the colour differences are more profound. Similar to the crust, incorporation of dateseed flour darkened the crumb colours significantly with decreased L* values (p<0.05) and increased the redness and decreased yellowness. As expected, then effect of fibre sources in the crumb more easily noticed when compared to the crust since the effect of high temperature and caramelization more limited in the crumb⁸.

In conclusion, as usage of some different fibre sources in combination (date seed and quinoa flour substituted samples, DQ), gave better results for muffin quality; combined usage of different fibre sources might suggested as an efficient way to overcome the disadvantages of dietary fibre sources on muffin quality. Future studies might focus on further possible fibre combinations and physicochemical properties in detail.

Acknowledgements

No acknowledgements to declare.

Funding Sources

Hamzacebi made the experiments of this study during her food engineering master studies at Istanbul Aydin University Graduate School of Science Engineering and Technology. The authors received no financial support for the research, authorship, and/or publication of this article.

Conflict of Interest

Authors state no conflict of interest for the study.

References

1. Tacer-Caba Z, Nilufer-Erdil D, Ai Y. Chemical Composition of Cereals and Their Products. In: Cheung PCK, Mehta BM, eds. Handbook of Food Chemistry. Springer Berlin Heidelberg; 2014:1-23.
   CrossRef
2. Conforti F. Cake manufacture. In: Zhou W, ed. Bakery products: Science and technology. John Wiley & Sons, Ltd; 2006:393-410.
   CrossRef
3. HadiNezhad M, Butler F. Effect of flour type and baking temperature on cake dynamic height profile measurements during baking. journal article. Food and Bioprocess Technology. August 01 2008;3(4):594-602. doi:https://doi.org/10.1007/s11947-008-0099-1.
   CrossRef
4. !!! INVALID CITATION !!! 4-6;
5. Ambigaipalan P, Shahidi F. Date seed flour and hydrolysates affect physicochemical properties of muffin. Food Bioscience. 2015/12/01/ 2015;12:54-60. doi:https://doi.org/10.1016/j.fbio.2015.06.001
   CrossRef
6. Lebesi DM, Tzia C. Effect of the addition of different dietary fiber and edible cereal bran sources on the baking and sensory characteristics of cupcakes. journal article. Food and Bioprocess Technology. July 01 2011;4(5):710-722. doi:https://doi.org/10.1007/s11947-009-0181-3.
   CrossRef
7. Masoodi FA, Sharma B, Chauhan GS. Use of apple pomace as a source of dietary fiber in cakes. journal article. Plant Foods for Human Nutrition. March 01 2002;57(2):121-128. doi:https://doi.org/10.1023/a:1015264032164.
   CrossRef
8. Struck S, Gundel L, Zahn S, Rohm H. Fiber enriched reduced sugar muffins made from iso-viscous batters. LWT – Food Science and Technology. 2016/01/01/ 2016;65:32-38. doi:https://doi.org/10.1016/j.lwt.2015.07.053
   CrossRef
9. Sudha ML, Baskaran V, Leelavathi K. Apple pomace as a source of dietary fiber and polyphenols and its effect on the rheological characteristics and cake making. Food Chemistry. 2007/01/01/ 2007;104(2):686-692. doi:https://doi.org/10.1016/j.foodchem.2006.12.016.
   CrossRef
10. Foschia M, Peressini D, Sensidoni A, Brennan M, Brennan C. Synergistic effect of different dietary fibres in pasta on in vitro starch digestion? Food Chemistry. 2015/04/01/ 2015;172:245-250. doi:https://doi.org/10.1016/j.foodchem.2014.09.062.
    CrossRef
11. Liu RH. Whole grain phytochemicals and health. Journal of Cereal Science. 2007/11/01/ 2007;46(3):207-219. doi:https://doi.org/10.1016/j.jcs.2007.06.010.
    CrossRef
12. Brennan MA, Lan T, Brennan CS. Synergistic effects of barley, oat and legume material on physicochemical and glycemic properties of extruded cereal breakfast products. Journal of Food Process and Preservation. 2016/06/01 2015;40(3):405-413. doi:https://doi.org/10.1111/jfpp.12617
    CrossRef
13. Foschia M, Peressini D, Sensidoni A, Brennan CS. The effects of dietary fibre addition on the quality of common cereal products. Journal of Cereal Science. 2013/09/01/ 2013;58(2):216-227. doi:https://doi.org/10.1016/j.jcs.2013.05.010.
    CrossRef
14. Foschia M, Peressini D, Sensidoni A, Brennan MA, Brennan CS. How combinations of dietary fibres can affect physicochemical characteristics of pasta. LWT – Food Science and Technology. 2015/04/01/ 2015;61(1):41-46. doi:https://doi.org/10.1016/j.lwt.2014.11.010.
    CrossRef
15. Aydogdu A, Sumnu G, Sahin S. Effects of addition of different fibers on rheological characteristics of cake batter and quality of cakes. Journal of Food Science and Technology-Mysore. 2018/02/01 2018;55(2):667-677. doi:https://doi.org/10.1007/s13197-017-2976-y.
    CrossRef
16. Bhise S, Kaur A. Fortifying muffins with psyllium husk fibre, oat fibre and barley fibre to improve quality and shelf life. Article. Carpathian Journal of Food Science & Technology. 2015;7(2):5-16.
17. Inglett GE, Chen D, Liu SX. Pasting and rheological properties of quinoa‐oat composites. Internationa Journal of Food Science and Technology. 2015;50(4):878-884. doi: https://doi.org/10.1111/ijfs.12722|
    CrossRef
18. Soong YY, Tan SP, Leong LP, Henry JK. Total antioxidant capacity and starch digestibility of muffins baked with rice, wheat, oat, corn and barley flour. Food Chemistry. 2014/12/01/ 2014;164:462-469. doi:https://doi.org/10.1016/j.foodchem.2014.05.041.
    CrossRef
19. Elgeti D, Nordlohne SD, Föste M, et al. Volume and texture improvement of gluten-free bread using quinoa white flour. Journal of Cereal Science. 2014/01/01/ 2014;59(1):41-47. doi:https://doi.org/10.1016/j.jcs.2013.10.010.
    CrossRef
20. Alvarez-Jubete L, Auty M, Arendt EK, Gallagher E. Baking properties and microstructure of pseudocereal flours in gluten-free bread formulations. journal article. European Food Research and Technology. November 25 2009;230(3):437. doi:https://doi.org/10.1007/s00217-009-1184-z
    CrossRef
21. Wang S, Opassathavorn A, Zhu F. Influence of quinoa flour on quality characteristics of cookie, bread and Chinese steamed bread. Journal of Texture Studies. 2015;46(4):281-292. doi:https://doi.org/10.1111/jtxs.12128|
    CrossRef
22. Goyat J, Passi S, Suri S, Dutta H. Development of chia (salvia hispanica, l.) and quinoa (chenopodium quinoa, l.) seed flour substituted cookies-physicochemical, nutritional and storage studies. Current Research in Nutrition and Food Science Journal. 2018;6(3):757-769.
    CrossRef
23. Al-Farsi MA, Lee CY. Nutritional and functional properties of dates: A review. Critical Reviews in Food Science and Nutrition. 2008/10/21 2008;48(10):877-887. doi:https://doi.org/10.1080/10408390701724264
    CrossRef
24. Gularte MA, de la Hera E, Gómez M, Rosell CM. Effect of different fibers on batter and gluten-free layer cake properties. LWT – Food Science and Technology. 2012/10/01/ 2012;48(2):209-214. doi:https://doi.org/10.1016/j.lwt.2012.03.015
    CrossRef
25. AOAC-International. AOAC International Official Methods of Analysis. Association of Official Analytical Chemists; 2002.
26. Approved Methods of the AACC 10th edn. ed. American Association of Cereal Chemists International Press; 2000.
27. Gullon B, Pintado ME, Barber X, Fernández-López J, Pérez-Álvarez JA, Viuda-Martos M. Bioaccessibility, changes in the antioxidant potential and colonic fermentation of date pits and apple bagasse flours obtained from co-products during simulated in vitro gastrointestinal digestion. Food Research International. 2015/12/01/ 2015;78:169-176. doi:https://doi.org/10.1016/j.foodres.2015.10.021
    CrossRef
28. Romano A, Masi P, Bracciale A, Aiello A, Nicolai MA, Ferranti P. Effect of added enzymes and quinoa flour on dough characteristics and sensory quality of a gluten-free bakery product. European Food Research and Technology. 2018;doi:https://doi.org/10.1007/s00217-018-3072-x
    CrossRef
29. Maphosa Y, Jideani VA. Dietary fiber extraction for human nutrition—A review. Food Reviews International. 2016/01/02 2016;32(1):98-115. doi:10.1080/87559129.2015.1057840.
    CrossRef
30. Gómez M, Moraleja A, Oliete B, Ruiz E, Caballero PA. Effect of fibre size on the quality of fibre-enriched layer cakes. LWT – Food Science and Technology. 2010/01/01/ 2010;43(1):33-38. doi:https://doi.org/10.1016/j.lwt.2009.06.026.
    CrossRef
31. Pomeranz Y, Shogren M, Finney K, Bechtel D. Fiber in breadmaking–effects on functional properties. Cereal Chemistry. 1977;
32. Topkaya C, Isik F. Effects of pomegranate peel supplementation on chemical, physical, and nutritional properties of muffin cakes. Journal of Food Processing and Preservation. 2019;43(6):e13868. doi:10.1111/jfpp.13868.
    CrossRef
33. Chang R-C, Chia-Yen L, Shiau S-Y. Physico-chemical and sensory properties of bread enriched with lemon pomace fiber. Czech Journal of Food Sciences. 2015;33(2)doi:https://doi.org/10.17221/496/2014-CJFS
    CrossRef
34. Martínez-Cervera S, Salvador A, Muguerza B, Moulay L, Fiszman SM. Cocoa fibre and its application as a fat replacer in chocolate muffins. LWT – Food Science and Technology. 2011/04/01/ 2011;44(3):729-736. doi:https://doi.org/10.1016/j.lwt.2010.06.035.
    CrossRef
35. Gómez M, Ronda F, Caballero PA, Blanco CA, Rosell CM. Functionality of different hydrocolloids on the quality and shelf-life of yellow layer cakes. Food Hydrocolloids. 2007/03/01/ 2007;21(2):167-173. doi:https://doi.org/10.1016/j.foodhyd.2006.03.012.
    CrossRef
36. Bchir B, Rabetafika HN, Paquot M, Blecker C. Effect of pear, apple and date fibres from cooked fruit by-products on dough performance and bread quality. Food Bioprocess Technology. 2014/04/01 2014;7(4):1114-1127. doi:https://doi.org/10.1007/s11947-013-1148-y.
    CrossRef
37. Ocheme A, Olajide E, Chinma CE, Yakubu CM, Ajibo UH. Proximate composition, functional, and pasting properties of wheat and groundnut protein concentrate flour blends. Food Scence & Nutrition. 2018; 6(5): 1173-1178. doi: https://doi.org/10.1002/fsn3.670.
    CrossRef
38. Ortega-Heras M, Gómez I, de Pablos-Alcalde S, González-Sanjosé ML. Application of the just-about-right scales in the development of new healthy whole-wheat muffins by the addition of a product obtained from white and red grape pomace. Foods. 2019, 8(9), 419. doi: https://doi:10.3390/foods8090419.
    CrossRef
39. Oluwajuyitan TD, Ijarotimi OS, Fagbemi TN. Nutritional, biochemical and organoleptic properties of high protein-fibre functional foods developed from plantain, defatted soybean, rice-bran and oat-bran flour. Nutrition & Food Science. 2020, doi: https://doi.org/10.1108/NFS-06-2020-0225.
    CrossRef
40. Yohannes TG, Makokha AO, Okoth JK, Tenagashaw MW. Developing and nutritional quality evaluation of complementary diets produced from selected cereals and legumes cultivated in Gondar province, Ethiopia. Current Research in Nutrition and Food Science Journal. 2020, 8(1), 291-302. doi: http://dx.doi.org/10.12944/CRNFSJ.8.1.27.
    CrossRef
41. Duţă DE, Culeţu A, Mohan G. Reutilization of cereal processing by-products in bread making. In: Sustainable Recovery and Reutilization of Cereal Processing By-Products (pp. 279-317). 2018, Woodhead Publishing.
    CrossRef