Fonksiyonel üzüm ekstraktı içeren ekmek ve ekstrüde ürünlerin fonksiyonel özelikleri ve kalite parametreleri

Cereal products are commonly considered as staple foods for human beings and have been significant for nations' nutrition for ages. They play an important role in diets of humans throughout the world. However, recent trends are developing functional cereal products by means of adding functional ingredients. Concord grape is one of those ingredients which is known as a rich source of bioactive compounds, particularly different flavonoids. The objective of this study is to evaluate the effect of adding Concord grape extract powder (CGEP) alone and together with amylose and protein to see their interactions and effects on the quality and functional properties of two common cereal products, bread and extruded snack. This thesis involves eight chapters consisting of introduction, literature review, materials and methods followed by 4 separate chapters of results and discussions consisting of: proximate analysis, physicochemical properties and functional properties of flour mix samples, CGEP added bread, CGEP added extrudates, comparison of functional properties for those cereal products, and finally conclusion chapter. Following the introduction on the scope of the study, a short literature review about the current knowledge on cereal products especially bread and extruded products and phenolic compounds commonly found in grapes and recent studies on cereal products involving different fruit sources were covered. In Chapter 3, all materials and methods used in the study were explained in detail. Six different flour mix samples were prepared to evaluate the interactions of CGEP and high amylose corn starch (HACS) and six other flour mixes were prepared to evaluate the interactions of CGEP and wheat protein isolate (WPI). Amylose substituted flour mix samples comprised of hard wheat bread flour substituted at three different levels of HACS together with 7% CGEP and without CGEP. For preparation of protein substituted samples three different levels of WPI together with 7% CGEP and without CGEP were used. For preparation of bread samples AACC International 10-10B method of Optimized-Straight-Dough-Bread-Making was used without ascorbic acid. For extrusion trials a laboratory scale twin screw extruder was used with a constant feed moisture (25%) and screw speed (360 rpm). The low shear configuration was applied and three different processing temperature profiles of 90, 120 and 150ºC at exit die were used. For proximate properties of native flour sample mixes, total moisture, ash and protein contents were determined. Moreover, total starch, total resistant starch, amylose/amylopectin ratio of samples were measured using enzymatic/gravimetric methods. Flour water absorption properties were measured using Farinograph and flour pasting properties were determined by using Rapid Visco Analyzer (RVA). Afterwards, baked bread samples were tested for bread quality properties such as crumb firmness analyzed by texture analyzer, loaf volume and loaf specific volume by rapeseed displacement method, color parameters using chromameter and microscopic images using scanning electron microscope (SEM). Extruded samples were also tested for their quality parameters such as specific mechanical energy (SME), pasting properties using RVA, hardness using texture analyzer, bulk density, diametric expansion, water absorption, resistant starch and also thermal properties using Differential Scanning Calorimetry (DSC). Then, analyses were carried out to evaluate the functional properties of bread and extruded samples. In this respect, total phenolic content, total antioxidant activity, total anthocyanin content and total flavonoid contents of products were measured using spectrophotometric methods. More detailed analysis of individual phenolic compounds were made using reversed-phase HPLC (high performance liquid chromatography) coupled with PDA. Differences among samples were tested by analysis of variance (ANOVA) and Duncan's New Multiple Range Test. Results of proximate analysis and physicochemical tests were given In Chapter 4, and results revealed that, ash content in samples with CGEP and protein content in WPI substituted samples were significantly higher than the other samples (p<0.05). Resistant starch content of HACS substituted samples were higher than the rest of the samples. No significant difference was detected in the total starch contents. Amylose content correlated with HACS substitution as expected and increased from 20.6-26.5% to 31.0-41.7% for control sample (A1) and only CGEP substituted sample (GA1), respectively. Flour water absorption was higher in HACS and WPI substituted samples. CGEP addition resulted in no significant changes in the water absorption properties of the flour sample mixes (53.6-55.7%). Flour pasting properties revealed CGEP as the most detrimentally effected ingredient on the flour gel formation. Moreover, presence of WPI or HACS was not effective on the recovery of pasting properties. In Chapter 5, first rheological dough characteristics and bread-making qualities of bread samples baked for protein treatment were evaluated to elicit possible interactions mainly due to WPI and CGEP. Bread samples with only CGEP (as in GP1 breads) were firmer (3-4 times firmer), while together with CGEP and WPI addition, breads became softer in texture. Increases in WPI content within control samples made significant increases in loaf volumes. However, the loaf volumes were lower than control samples in CGEP and WPI substituted breads, therefore possible interactions between phenolics and proteins might have prevented further increase in volume. Same parameters were also evaluated with bread samples baked using CGEP and HACS. According to the results, firmness of the bread samples increased with CGEP and HACS to higher levels. Volume and specific volume measurements decreased significantly with the use of CGEP and CGEP + HACS in combination (p<0.05). The functional properties of bread samples started with the results on functional properties of ingredients. Total amount of phenolics in CGEP and control hard wheat bread flour was found as 34623.8±2934.7 mg GAE/ 100 g DW and 721.8±6.5 mg GAE/100 g DW, respectively. After CGEP (7%) substitution, total phenolic content of hard wheat flour with CGEP was found as 2374.2±89.2 mg GAE/100 g DW. Therefore, CGEP (7%) substitution increased the amount of total phenolics around to a 3 times higher level. Besides, flour with CGEP (7%) had also a significantly higher antioxidant activity, flavonoid and anthocyanin contents with respect to control wheat flour after substitution. In the last part of the chapter, the functional properties of individual parts of crust, crumb and dough of bread samples with CGEP and together with WPI and HACS were evaluated. Total phenolics and total antioxidant activity (both DPPH and ABTS radical scavenging activity) significantly increased after CGEP substitution in comparison to no CGEP samples. Loss (%) of phenolics and antioxidant activities due to baking in comparison to unprocessed flour samples mixes were higher in samples without CGEP, although HACS or WPI substitution made no significant recoveries in % losses in samples with CGEP. In CGEP substituted samples, phenolic content of dough samples were significantly higher than that of crumb and crust parts (p>0.05). Increasing levels of WPI substitution decreased the total flavonoids in crumb and dough significantly (p<0.05). According to the HPLC-PDA results in control samples baked without CGEP, protocathechuic acid, gallic acid, sinapic acid, vanillic acid, p-coumaric and ferulic acid were the major phenolic compounds that were detected. Gallic acid and vanillic acid were found to increase significantly (around 2-fold) after baking. Therefore, increase in WPI substitution level did not make any certain effects on the phenolic compounds found in crust, crumb and dough of no-CGEP added samples. Gallic acid was also dominant phenolic acid in CGEP substituted bread samples. Syringic acid, p-coumaric acid, sinapic acid and epigallocatechin were also present in CGEP added bread samples but the content of these compounds were much lower (around 10-15 μg/100 g DW). Rutin was the most abundant flavonol in CGEP added bread samples, although it was lost as much as 25 % during baking. For rutin and quercetin-3-β-glucoside, increase in WPI level had a preserving effect. On the other hand, significant decreases in delphinidin-3-o-glucoside, delphinidin, cyanidin-3-o-glucoside, and cyanidin-3,5-diglucoside in particularly crust of bread samples were evident. No change in cyanidin was detected. Level of HACS substitution made no significant effects on measured phenolic content of these samples (p>0.05). All control samples containing only HACS had significantly lower levels of phenolics than samples with CGEP and HACS (p<0.05), although level of HACS substitution made no significant effects on measured phenolic content of these samples (p>0.05). In addition, crusts of those samples have a significantly higher level of phenolic content (p<0.05) than crumb. Level of HACS substitution made no significant effect on the antioxidant activity of those samples (p>0.05). Percent loss was highest in the crumb of no-CGEP added samples (77%). Generally HACS addition had no effect on the loss (%) of antioxidant activity analyzed by ABTS method, only exceptions were for dough and crust of 20% HACS substituted bread samples. Before HACS substitution, bread sample with only CGEP seemed to have an insignificant difference in flavonoid content between parts of bread samples and dough (p>0.05). However, HACS seemed to decrease the measured amount of flavonoids in the crust and crumb. Therefore, amylose substitution decreased flavonoids significantly (p<0.05) in crust and crumb but made no effect for the dough. Flavonoid contents of the crust and crumb decreased with the increase in HACS level, whereas for dough no change was seen. Although the anthocyanin content of bread samples with only CGEP substitutions were statistically similar (p>0.05), dough had significantly higher total anthocyanins than crust and crumb of bread after HACS addition. According to HPLC results, control bread samples, without CGEP, had the highest concentrations of phenolic acids as gallic acid (2.4 to 18 μg/100 g DW) and vanillic acid (3.38 to 12.39 μg/100 g DW). For some phenolic compounds; such as procathechuic acid, epigallocatechin, catechin hydrate, vanillic and p-coumaric acids, crumb had higher concentrations than dough. HACS substitution made no significant change in the measured phenolics of no-CGEP added breads. Quercetin-3-β-glucoside,delphinidin 3-O-glucoside, cyanidin 3-O-glucoside and their diglucosides, also anthocyanidins such as; delphinidin, cyanidin, malvidin and its glucosides were detected in CGEP added breads. Flavonols displayed no significant differences among crumb, crust and dough (p>0.05). However significant differences were observed between the anthocyanin profiles of crust, crumb and dough of bread samples. Generally crusts had lower amounts of anthocyanin compounds, as temperature during baking was the highest one among different parts. On the other hand; HACS substitution seemed to have no effect on the remaining flavonols and anthocyanins. Only exception was malvidin, since the malvidin content increased with the increase in HACS substitution. In the next chapter (Chapter 6) first of all the effects of CGEP and WPI on quality parameters of hard wheat flour extrudates were investigated. Results revealed that CGEP substitution (7%), even with WPI (6.5 and 13%), was not so much effective on quality of extrudates extruded at 90 and 120ºC barrel temperatures. The only parameter effective on quality was the temperature; especially at 150ºC, differences between formulations were more distinct for (diametric expansion, bulk density) when compared to lower die temperatures (90 and 120ºC). However, pasting properties were detrimentally affected by the single addition of CGEP (about 55.4% loss in final viscosity) with respect to single WPI substitution (about 66.7% loss in final viscosity). Presence of both CGEP and WPI made the pastes even weaker (34.1 to 61.1% decrease in peak viscosity). Besides, no distinct effects on retrogradation was observed neither by CGEP nor with WPI. Therefore, in extrudates, loss of protein content by means of CGEP substitution did not exert a significant quality loss and even by increasing the protein level no improvement in quality parameters was obtained. Chapter 6 also comprised the effects of CGEP, HACS, and their combinations on quality parameters of extruded products. Average values obtained for 90, 120 and 150ºC extrusion temperatures changed respectively as follows: 0.916, 0.987 and 0.467 N for hardness; 2.12, 4.07 and 5.12 ml water/g sample for water absorption; 1.35, 2.09 and 2.51 for diametric expansions and 1286.6, 723.6 and 311.1 kg/m3 for bulk densities. Extrusion temperature was found to have more distinct effect on physical quality parameters of extrudates than the substitution level of ingredients. Both CGEP and HACS additions negatively affected pasting properties, slightly affected resistant starch content and prevented gelatinization. However retardation of retrogradation was more evident when substitution was with CGEP alone rather than its combination with HACS. The last part of Chapter 6 was on the evaluation of the functional properties of the extrudates. Total phenolic content of the extrudates ranged between 129.5±0.2 and 2095.7±1.0 mg GAE/100 g DW. In no CGEP substituted samples, phenolic contents of the samples significantly decreased with the increase in extrusion temperature (p<0.05). Measured amount of phenolics increased significantly with the increase in WPI level. WPI substitution was found as a significant factor to decrease the % loss of phenolics and antioxidant activity (ABTS radical scavenging activity) after extrusion in samples without CGEP at 90ºC and 120ºC. On the other hand, the same effect was not evident in CGEP substituted samples. Extrusion temperature made no significant effect on the measured total antioxidant activity by DPPH radical in samples with no CGEP (p<0.05). CGEP substituted samples increased the total antioxidant activity of samples significantly. Extrusion temperature made a significant decrease in the antioxidant activity only at 150ºC (p<0.05). Substitutions with WPI made a significant increase of ABTS radical scavenging activity only in samples extruded at 90ºC (p<0.05). In samples with CGEP, antioxidant activity was significantly lower (p<0.05) at 150ºC than the other extrusion temperatures. Total flavonoid contents of samples changed between 1499.8±26.6 and 2262.3±33.1 mg QE/ 100 g DW. Substitutions of WPI and gradual increase of substitution level seemed to increase the total flavonoid content in all different extrusion temperatures, although the differences were not statistically significant (p>0.05). WPI substitutions generally they decreased the measured anthocyanin contents. However their effect was not found to be statistically significant (p>0.05). Increase in extrusion temperature had a detrimental effect on phenolics and flavan-3-ols, generally. Gallic acid increased significantly with the WPI level in CGEP substituted samples. For sinapic acid (in samples without CGEP), and epigallocatechin, catechin hydrate, epicatechin, syringic acid, epicatechin gallate and vanillic acid (for samples with CGEP) similar linear trends were detected with WPI, although the effects were changing in statistical significance. Amount of total phenolics in HACS extrudate samples changed between 108.8±0.7 and 1947.5±39.4 mg GAE/100 mg DW. In samples with no CGEP substitution, from 90ºC to 120ºC significant decreases in total phenolic content were evident at all HACS substitution levels (p<0.05). Increase in extrusion temperature had no significant effect on the antioxidant activities (DPPH) of no-CGEP added extrudate samples. HACS increased the % loss of antioxidant activity in all samples (with or without CGEP). Antioxidant activity measured by ABTS method was not affected from die temperatures in samples without CGEP, whereas significant decreases were detected in CGEP samples with increases in extrusion temperatures. HACS substitutions also decreased the antioxidant activity significantly (p<0.05). According to the results; flavonoid contents of the samples were between 1492.6±134.7 and 1970.6±198.0 mg QE/ 100 g DW. HACS substitution levels did not make any significant change on the measured flavonoid content of the extrudates (p>0.05). When the flavonoid contents of extrudates were compared with the unprocessed flour samples, it was observed that extrusion at 90ºC increased the total amount of flavonoids, in an average level of 12%. Neither the effect of HACS levels, nor the extrusion temperature was found significant on the anthocyanin level measured. In no-CGEP added samples, only sinapic acid (at 150ºC), gallic acid (120 and 90ºC), and vanillic acid (90ºC) increased with HACS substitutions. In samples with CGEP on the other hand, gallic acid content revealed significant increases by HACS substitution, at 150ºC and 120ºC while no effect was observed at extrusion temperature of 90ºC. In Chapter 7, the results of comparison of bread crumb samples and extrudate samples with CGEP revealed that anthocyanin compounds were better retained in bread samples. HACS substitution better retained the phenolic compounds in extrudates, while WPI gave better results in bread samples. After HACS or WPI substitutions flavonoid content of bread crumbs decreased about 50%. For samples extruded at 150ºC on the other hand, flavonoid contents were better retained as about 20 % increase was observed. WPI substitutions had detrimental effects on total anthocyanin content, whereas HACS act as an improver for the measured anthocyanin contents both for bread crumb and extruded product samples As a conclusion of this thesis (Chapter 8) it was obtained that addition of CGEP increased the total phenolic content of extrudates about 10-fold, whereas for bread it provided 10-14 fold increase with respect to no-CGEP added products. So it can be said that addition of CGEP increased the functionality of the cereal products in a significant manner. However WPI substitution besides CGEP gave better quality in bread samples whereas for extrudates CGEP addition had not so much detrimental effect on the quality. WPI level of 6.5% seemed to preserve the bioactive compounds in a better way with respect to other levels of substitution. Whereas for HACS substitutions no specific was evident for different substitution levels.