The Effects of the Mixed Fermentation of Honeysuckle Cereal Mixed Flour on the Dough Characteristics and Bread Quality

Abstract

This study investigated the effects of the mixed solid fermentation of honeysuckle cereal mixed flour with lactic acid bacteria and yeast on dough characteristics and bread quality. Honeysuckle powder and whole wheat flour were mixed to make reconstituted cereal flour, and yeast and Lactobacillus plantarum were implanted and mixed to make dough for fermentation. The dynamic rheological properties of the dough were determined, and the properties of the reconstituted cereal flour bread were determined, including the texture characteristics and color; then, the sensory evaluation and antioxidant capacity of the bread were determined. The storage modulus (G′) and loss modulus (G″) of the dough increased gradually with the increase in the honeysuckle powder content, and the loss tangent value, tanδ (G″/G′), was less than 1.0. The loss tangent value of the dough had no significant change (p > 0.05) with the increase in honeysuckle powder content; the L* value of the bread decreased from 88.50 to 76.00, the a* value increased from −1.87 to 0.79, and the b* value decreased from 21.04 to 13.68 with the increase in the amount of honeysuckle powder. When the honeysuckle powder addition was 4%, the reconstituted cereal bread was bright yellow and gave off a hint of bean and wheat flavor and had the best taste and quality. The hardness, chewiness, and the recovery of the bread decreased when the content of the honeysuckle powder was in the range of 0~4%, but the elasticity and the antioxidant and antiaging activity of the bread increased significantly (p > 0.05). It was determined that the best content of honeysuckle powder was 4%. The mixed microbial fermentation of honeysuckle cereal mixed flour can improve the quality and enhance the nutritional value of bread.

1. Introduction

Modern society suggests that people should focus on prevention in terms of nutrition and health, and consumers are paying more attention to diet health. Flour products provide a large amount of carbohydrates and are resisted as a staple food by people with obesity. The bakery industry is facing opportunities for development; a wide variety of baked foods have appeared on the market, especially in recent years, and the prepared food industry has become a hot topic, where baked goods such as pizza, pie, and whole grain bread have rapidly developed [1]. In order to improve the nutritional value and health level of flour products, some researchers have studied fermented flour products, whole grain foods, and frozen flour products [2,3]. Whole grains refer to grains with endosperm, germ, bran, and natural nutrients that have not been treated by precision processing methods such as milling, crushing, and tableting [4,5]. Whole grains not only contain the rough outer parts of the grains but also contain antioxidant components, vitamin B, dietary fiber, minerals, and other phytochemicals [6,7]. Honeysuckle is famous for its medicinal value. It is mainly used to clear away heat and toxic materials, improve immunity, inhibit cancer cell proliferation, inhibit intestinal absorption of cholesterol, etc. [8]. In particular, it has a unique weight loss effect, and it is a natural weight loss food for people with obesity [9]. Some of the literature has shown that the main bioactive components in honeysuckle are chlorogenic acid, luteolin, lonicerin, 5-hyfroxy-3′-4′-7-trimethoxyflavone, etc. [10].

Bread is a major part of our daily diet, and since it produces rich nutrients through fermentation, yeast is a common microorganism in making bread [11]. Fermentation can not only improve the nutrition and taste of the bread but also prolong its shelf life [12,13]. Lactic acid bacteria fermentation can improve the digestibility of protein in vitro, and the lactic acid produced can acidify the food matrix and prolong the shelf life. It can also solve the problem of the difficulty in setting, due to the insufficient gluten in grain flour, and make the bread have a better flavor and taste [14,15,16]. At present, there are few studies on making bread by the mixed fermentation of honeysuckle cereal mixed flour with yeast and lactic acid bacteria. The development of functional foods that have positive effects on consumers’ health is a trend in the food industry. Cereals, fruits, vegetables, probiotics, etc., can be added to the traditional bread production process as a source of functional ingredients [17]. Thus, honeysuckle as a source of antioxidants, soluble dietary fiber, polyphenols, minerals, and vitamins enriches the nutritional value and functional characteristics of bread [18]. At present, there is little research on adding honeysuckle to wheat flour to make products, and there is also little research on mixed cereal flour fermentation using mixed strains.

Therefore, in this research, we ground honeysuckle into a powder and mixed it with whole cereal flour according to a certain ratio to prepare reconstituted cereal flour and made bread by fermenting the reconstituted cereal powder with yeast and lactic acid bacteria. The effects of the addition of honeysuckle powder on the dough’s rheological characteristics, the bread texture characteristics, color index, sensory evaluation, and antioxidant and antiaging activities were deeply studied, which provide a theoretical and practical basis for the production of honeysuckle reconstituted cereal flour bread.

2. Materials and Methods

2.1. Materials and Reagents

Whole wheat flour and yeast powder were purchased from local supermarkets, and their nutrients included energy 18%, protein 21%, fat 3%, carbohydrate 24%, and sodium 0%. Lactobacillus plantarum powder was preserved in the laboratory, and the number of viable bacteria was 1 × 10¹¹ CFU/g. Honeysuckle was provided by the Honeysuckle Experimental Base in Yanjin County (protein 23.1 g/100 g, lipid 5.7 g/100 g, flavonoid 4.9 g/100 g, polysaccharide 6.6 g/100 g, and dietary fibers 17.7 g/100 g). 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferrous sulfate, salicylic acid, hydrogen peroxide, potassium ferricyanide, and trichloroacetic acid were purchased from e (Dalian, China). Other reagents were purchased from Kermel Chemical Reagent Co., Ltd. (Tianjin, China). All the chemicals were analytical grade.

2.2. Preparation of the Honeysuckle Cereal Mixed Flour

Honeysuckle (20 kg) was dried in the oven (Gravity Convection, Thermo Fisher, Waltham, MA, USA) at a temperature of 55 °C, a time of 90 min, and a relative humidity of 20%. Then, 100 g of honeysuckle was collected and milled with a high-speed pulverizer (FW-100, Taisite, Tianjin, China) at 20,000 r/min for 50 s and turned into honeysuckle powder, which was passed through a 0.25 mm sieve [19]. After screening and removing the impurities, it was mixed for later use. Honeysuckle powder and whole wheat flour were mixed according to the mass fraction of 0, 1%, 2%, 3%, 4%, 5%, 6%, and 7%, respectively, to prepare the honeysuckle cereal mixed flour [20].

2.3. Preparation of the Honeysuckle Cereal Mixed Flour Bread

Whole wheat flour and honeysuckle powder at a specific proportion (0, 1%, 2%, 3%, 4%, 5%, 6%, and 7%), 2% yeast powder, 4% Lactobacillus plantarum powder, 4% salt, and 5% sugar (mass ratios above) were mixed together into a dry premix. Then, 500 g of the mixed solid raw material, 4% edible oil, and 300 mL of water were mixed in a dough kneading machine (HC-H02, Century Huachu, Jinan, China) for 12 min at 50 rpm [19,21]. The honeysuckle cereal mixed flour bread was made by secondary fermentation (primary fermentation: temperature 30 °C, humidity 90%, time 2 h; secondary fermentation: temperature 30 °C, humidity 90%, time 20 min). The fermented dough was placed in the oven (MOE-2412S, Meichu, Beijing, China) at a surface fire of 190 °C and a primer fire of 200 °C for 30 min; the baked bread was taken out, left to cool at room temperature for 1 h, and packed in a sealed vacuum bag at room temperature until analysis.

2.4. Determination of the Rheological Properties of the Honeysuckle Cereal Mixed Flour Dough

The honeysuckle cereal mixed flour dough’s rheological properties were determined with reference to the Arufe and Dixit [22] method. After kneading the dough, we wrapped it in plastic wrap and let it stand at 20 °C for 10 min before testing. The measurement conditions were as follows: a plate diameter of 40 mm, a distance between plates of 1 mm, a temperature of 26 °C, and a frequency scanning area of 0.1–10 Hz. A P35Til fixture was used, and the test strain was selected as 0.1% according to the linear viscoelastic region scanning results. The instrument automatically recorded the curves of the energy storage modulus, the loss modulus, and the loss angle tangent with the frequency.

2.5. Determination of the Color Index of the Honeysuckle Cereal Mixed Flour Bread

Using a color difference meter (CR-400, Konica Minolta, Tokyo, Japan) and a bread sample of 10 cm × 10 cm × 2 cm, we chose three locations at the press distance of 0.5 mm, and then took the average [23]. The color was represented according to the uniform color stereogram system formulated by the CIE (Commission International Eclairage) (L axis (L*), a axis (a*), and b axis (b*)), where L* represents the black–white (brightness), a* represents the green–red, and b* represents the blue–yellow.

2.6. Determination of the Texture Characteristics of the Honeysuckle Cereal Mixed Flour Bread

The hardness, elasticity, chewiness, and recovery of the honeysuckle cereal mixed flour bread (2 cm × 2 cm × 2 cm) were measured by a texture analyzer (Food Technology Corporation (FTC), TMS-PRO, Sterling, VA, USA) with a P/35 probe, and the data were recorded [24]. The test parameters were set at a compression degree of 30%, an interval between two compressions of 5 s, a speed before detection of 1.2 mm/s, a speed during detection of 1.0 mm/s, a speed after detection of 1.2 mm/s, and a starting point inductance of 1.0 g.

2.7. Sensory Evaluation of the Honeysuckle Cereal Mixed Flour Bread

The sensory evaluation of the bread referred to Protonotariou and Pasqualone [1,25]. A sensory evaluation team composed of 10 people evaluated the sensory characteristics of the honeysuckle cereal mixed flour bread; the results were shown as the means ± SD. The sensory panelists consisted of five males and five females, all aged 25–45. The members of the sensory assessment team were trained by the Xinxiang Agricultural Product Processing Engineering Center and often carry out sensory assessments of baked food. All panel members had no food allergies or intolerances and were regular consumers of baked foods. Sensory analysis was carried out by quantitative descriptive analysis and performed in the sensory room, samples were randomly sent to sensory panelists, and rinsed with purified water between the two samples. The research protocol follows the ethical guidelines of the laboratory. The sensory panelists were given information about the aims of the study and written informed consent was received from each participant. All the tested samples were food grade, and the sensory evaluation was carried out for six aspects: morphology, elasticity, flavor, taste, texture, and color. The descriptors were rated on an anchored line scale that provided a 0–9 score range (0 = minimum and 9 = maximum intensity) of the morphology, a 0–24 score range (0 = minimum and 24 = maximum intensity) of the elasticity, a 0–22 score range (0 = minimum and 22 = maximum intensity) of the flavor, 0–10 score ranges (0 = minimum and 10 = maximum intensity) of the taste and of the texture, and a 0–25 score range (0 = minimum and 25 = maximum intensity) of the color; the total score was 100. The analyses were carried out in triplicate. The scoring criteria are shown in

Table 1. Scoring standard of the bread’s sensory characteristics.

Project	Evaluation Standard	Score
Morphology	The bread has a complete shape, uniform thickness, clear pattern, and no shrinkage and invariance	7~9
	The volume is slightly smaller; the surface is smooth and fluffy	5~7
	The bread has a small volume, a rough surface, and no cracks	<5
Elasticity	It is soft, has strong elasticity, and has a quick recovery after biting	18~24
	It is soft, slightly weak in elasticity, and recovers after biting	12~18
	It is not soft, has poor elasticity, and has a slow recovery after biting	<12
Flavor	The bread has a strong aroma and a mixed aroma of whole grain flour	18~22
	The taste is not pure, and the bread has a mild taste	14~18
	The taste is not pure, and the bread has a heavy bitter taste	<14
Taste	It has the taste of fermented and baked bread and does not stick to the teeth	8~10
	It has a bad taste	<8
Texture	The internal tissue structure is uniform, and the stomatal size is appropriate and uniform	8~10
	The internal tissue is compact and uniform, and the stomata are larger or smaller	6~8
	There is no fermentation inside	<6
Color	The color is even and glossy	20~25
	The color is uneven but glossy	15~20
	The color is dull and uneven	<15

.

2.8. Determination of the Antioxidant Activity of the Honeysuckle Cereal Mixed Flour Bread

One g of honeysuckle powder was weighed and mixed with 10 mL of 70% ethanol, employing an ultrasonic extractor (Daxlout-5CTL, Daluo Inc., Qingpu, China), and extracted (320 W) for 30 min. The sample extract was filtered through 0.22 μm syringe filters (Merck Millipore, Billerica, Switzerland). The total polyphenol content of honeysuckle powder was assessed using a modified version of the Folin-Ciocalteu assay [6].

2.8.1. DPPH Radical Scavenging Activity

Two mL of a 0.2 mmol/L DPPH alcohol solution was added to 2 mL of crude apple polyphenols extract liquid; the mixture was mixed well for half an hour in the dark, and the value of the OD₅₁₇ was measured. The value of the DPPH radical scavenging capacity was computed by the following formula, referring to the determination method of Musa [26]. The 0.2 mmol/L DPPH alcohol solution was the blank control.

2.8.2. •OH Radical Scavenging Activity

One mL of crude apple polyphenols extract liquid,1 mL 9 mmol/L FeSO₄, 1 mL salicylic ethanol solution, and 1 mL 8.8 mmol/L H₂O₂ were mixed well in sequence in a 10 mL centrifuge tube. Next, the mixture was placed in a water bath at 37 °C for 30 min; then, the value of the OD₅₁₀ was measured. The mixture of 1 mL distilled water, 1 mL 9 mmol/L FeSO₄, 1 mL salicylic ethanol solution, and 1 mL 8.8 mmol/L H₂O₂ was the blank control. The mixture of 1 mL of crude apple polyphenols extract liquid, 1 mL 9 mmol/L FeSO₄, and 1 mL salicylic ethanol solution was the background solution. The value of the •OH radical scavenging capacity was computed by the following formula, referring to Erdogan’s determination method [27].

2.8.3. Total Reducing Power

One mL of distilled water and 200 µL of crude apple polyphenols extract liquid were mixed well in a 10 mL centrifuge tube. Then, 2.5 mL of PBS (0.2 mol/L, pH 6.6) and 1% potassium ferricyanide solution were added. After 20 min in a water bath at 50 °C, 1 mL of 10% trichloroacetic acid solution was added; then, the mixture was centrifuged at 5000 r/min for 10 min. Next, the 2.5 mL supernatant was placed in another blank 10 mL centrifuge tube, and 2.5 mL of distilled water and 0.5 mL of 0.1% FeCl₃ were added; then, the OD₇₀₀ was determined [8].

2.9. Determination of the Antiaging Activity of the Honeysuckle Cereal Mixed Flour Bread

The bread was left at room temperature for 48 h; then, it was placed into a screen (hole diameter 0.36 mm) and mixed with 10 stainless steel balls (diameter of 5 mm), shocked for 5 min at 120 r/min. Then, the breadcrumbs under the screen were weighed; the quantity of the breadcrumbs in the unit of time was a measure of the degree of the bread aging standard. The more breadcrumbs under the screen, the worse the anti-aging performance of the product and the more serious the aging degree [28].

2.10. Data Analysis

The results were expressed by the mean ± standard deviation, the samples were replicated five times, the data were analyzed by SPSS 23.0 software, and the analysis of variance was calculated by the q-test multiple comparison method. p < 0.05 indicated that there was a significant difference in the statistics.

3. Results

3.1. The Effect of the Addition of Honeysuckle Powder on the Dynamic Rheological Properties of the Dough

The effect of the addition of honeysuckle powder on the dynamic rheological properties of the dough is shown in Figure 1. As can be seen from Figure 1A, B, the G′ (storage modulus) and G′ (loss modulus) of the dough gradually increased with the increase in honeysuckle powder addition, and the G′ was always higher than the G″ in the scanning frequency range of 0.1–10 Hz. It can be seen from Figure 1C that the loss tangent value tanδ (G″/G′) of the honeysuckle reconstituted cereal flour dough was lower than 1.0, indicating that the elastic modulus of the honeysuckle cereal mixed flour dough system was greater than the viscosity modulus. The results were similar to the rheological characteristics of weak gels. When the honeysuckle powder addition was in the range of 0~4%, there was no significant difference in the tanδ of the dough (p > 0.05), which indicated that the high polymer content and the polymerization degree of the gluten protein did not change obviously in the honeysuckle cereal mixed flour dough system. When the honeysuckle powder was in the range of 5~7%, the loss tangent tanδ first decreased and then increased, but the tanδ of the dough increased significantly in this range (p < 0.05) compared with the 0~4% honeysuckle powder, which indicated that the elastic modulus of the dough was lower than the viscosity modulus, and the crosslinking polymerization of the protein molecules decreased obviously in the dough system.

When the tanδ is smaller, the elasticity of the dough is higher. The addition of honeysuckle powder can increase the solid properties of the dough. Therefore, through the change in the tanδ, it can be judged that the formation of the gluten in the dough changed the elasticity of the dough. Through the dynamic rheological analysis of the honeysuckle cereal mixed flour dough with different dosages, the results showed that the storage modulus was always greater than the loss modulus in the scanning frequency range.

3.2. The Effect of the Addition of Honeysuckle Powder on the Bread Texture Characteristics

The effect of the addition of honeysuckle powder on the bread texture characteristics is shown in Figure 2. It can be seen from Figure 2A that with the increase in the amount of honeysuckle powder, the hardness of the reconstituted cereal bread fermented by yeast and Lactobacillus plantarum decreased, which may be due to the increase in the soluble dietary fiber content in the honeysuckle reconstituted cereal flour. Its water-holding capacity was enhanced, which caused the bread to absorb water and become inflated; thus, the hardness of the bread gradually reduced. When the amount of honeysuckle powder was 0~4%, the hardness of the bread did not change significantly (p > 0.05), but the hardness of the bread changed significantly (p > 0.05) when the honeysuckle powder was 5~7%. The elasticity of the bread changed significantly (p > 0.05) when the honeysuckle powder was 0~4%, and the higher the elasticity, the better the quality; when the honeysuckle powder was 5~7%, the elasticity of the bread did not change significantly (p > 0.05) (Figure 2B). Chewiness referred to the work of chewing bread until swallowing. The higher the chewiness, the less easy it was to chew. The chewiness of the bread changed significantly (p > 0.05) with the increase in the honeysuckle powder (Figure 2C). When the grains were crushed, the starch was crushed into starch particles, which damaged the content of the starch and caused the network structure of the starch and gluten to become loose, and the dough could not form good gluten protein. In addition, the larger the proportion of honeysuckle powder, the more the gluten quantity and the binding degree between protein and starch decreased, which affected the chewiness of the dough. It can be seen from Figure 2D that with the increase in the honeysuckle powder, the recovery of the bread was significantly different (p > 0.05), which showed that adding honeysuckle powder destroyed the gluten structure of the bread. In contrast, a good gluten network structure with a dense porous structure interacts with enough water for the dough to maintain a good water-holding capacity and inhibit starch aging.

3.3. The Effect of the Addition of Honeysuckle Powder on the Bread Color

Color has an important influence on the sensory evaluation of bread, and bread with a bright color can increase the appetite and improve the sensory evaluation scores.

Table 2. The effects of the addition of honeysuckle powder and the fermentation on the bread color.

Honeysuckle Powder Addition/%	L*	a*	b*
0	88.50 ± 0.45 a	−1.87 ± 0.11 f	21.04 ± 0.43 a
1	87.90 ± 0.27 a	−1.10 ± 0.05 e	19.38 ± 0.56 b
2	85.50 ± 0.42 b	−0.48 ± 0.01 d	18.97 ± 0.43 b
3	83.63 ± 0.37 c	−0.01 ± 0.06 c	16.54 ± 0.15 c
4	82.01 ± 0.22 d	0.45 ± 0.01 b	16.12 ± 0.52 c
5	80.58 ± 0.15 e	0.51 ± 0.06 b	15.64 ± 0.35 c
6	78.45 ± 0.25 f	0.73 ± 0.03 a	14.56± 0.65 cd
7	76.00 ± 0.65 g	0.79 ± 0.04 a	13.68 ± 0.47 d

Different lowercase letters in the same column indicate a significant difference (p < 0.05), while the same lowercase letters indicate no significant difference (p > 0.05).

shows that the L* value of the bread decreased from 88.50 to 76.00, and the b* value decreased from 21.04 to 13.68 with the increase in the amount of honeysuckle powder, both of which decreased significantly (p < 0.05), indicating that the brightness of the bread gradually dimmed, and the yellowness decreased. The a* value increased from −1.87 to 0.79 (p < 0.05), indicating that the red color of the bread increased and gradually tended to brown. With the increase in the honeysuckle powder, the L* and b* of the bread decreased significantly, while the a* increased significantly, indicating that the brightness of the bread decreased, which may be due to the high-speed crushing of the honeysuckle in the crushing process that led to an increase in the temperature, which caused the color of the honeysuckle powder to deepen, resulting in the decrease in the brightness of the bread.

3.4. The Effect of the Addition of Honeysuckle Powder on the Sensory Quality of the Bread

The effect of the addition of honeysuckle powder on the sensory quality of the bread is shown in

Table 3. The effects of the addition of honeysuckle powder and fermentation on the bread’s sensory qualities.

Honeysuckle Powder Addition/%	Morphology	Elasticity	Flavor	Taste	Texture	Color	Total Score (0–100)
0	9.1 ± 0.7 a	20.4 ± 0.9 c	21.4 ± 0.8 a	6.2 ± 0.5 e	10.0 ± 0.4 a	22.5 ± 0.4 c	89.6 ± 1.8 d
1	8.8 ± 0.6 b	21.9 ± 1.6 b	21.1 ± 0.9 a	6.8 ± 0.6 d	9.7 ± 0.5 a	22.6 ± 0.4 c	90.9 ± 2.3 c
2	8.6 ± 0.4 c	23.6 ± 2.4 a	20.9 ± 1.4 a	7.5 ± 0.4 c	9.5 ± 0.3 ab	24.1 ± 0.6 b	94.2 ± 3.3 b
3	8.5 ± 0.5 c	23.7 ± 1.5 a	20.8 ± 0.6 a	8.1 ± 0.7 b	9.2 ± 0.2 ab	23.8 ± 0.3 b	94.1 ± 2.5 b
4	8.5 ± 0.7 c	23.5 ± 2.1 a	20.1 ± 1.8 ab	9.6 ± 0.3 a	9.1 ± 0.6 b	25.6 ± 0.4 a	96.4 ± 3.6 a
5	6.1 ± 0.2 d	19.1 ± 0.9 d	19.6 ± 1.1 b	7.6 ± 0.9 c	7.5 ± 0.4 c	21.2 ± 0.9 d	81.1 ± 5.2 e
6	5.4 ± 0.3 e	18.2 ± 1.1 e	17.4 ± 1.3 c	6.1 ± 0.2 e	6.3 ± 0.6 d	18.3 ± 0.5 e	71.7 ± 1.4 f
7	4.2 ± 0.1 f	17.2 ± 1.3 f	15.1 ± 1.2 d	5.4 ± 0.5 f	5.3 ± 0.2 e	16.1 ± 0.2 f	63.3 ± 2.3 g

Note: Different lowercase letters in the same column indicate a significant difference (p < 0.05), while the same lowercase letters indicate no significant difference (p > 0.05).

. When the honeysuckle powder addition was 0~4%, the morphological score of the bread gradually decreased and showed significant changes (p < 0.05), but the score of the flavor had no significant changes (p > 0.05). The score of the texture had no significant changes (p > 0.05) within 0~3% honeysuckle powder. The scores of the elasticity, taste, and color of the bread gradually increased and showed significant changes (p < 0.05). When the honeysuckle powder was 5~7%, the color score of the bread decreased significantly (p < 0.05), and the color gradually faded; the texture score decreased significantly (p < 0.05), and the surface of the bread was rough and not smooth compared with that of the bread with 0~4% honeysuckle powder. Therefore, when the honeysuckle powder addition was 4%, the reconstituted cereal bread was bright yellow and gave off a hint of bean and wheat flavor; it had the best taste and quality. The bread made by adding 4% honeysuckle powder presented a burnt yellow appearance, which can arouse consumers’ appetite in terms of color, it had a fermented aroma, and the inside of the bread had a uniform aperture, good elasticity, and a chewy texture, which improved the sensory quality of the bread.

3.5. The Effect of the Addition of Honeysuckle Powder on the Antioxidant Activity of the Bread

The total polyphenol of honeysuckle powder was 24.53 ± 3.26 mg gallic acid equivalent (GAE)/g dry weight (DM). The antioxidant activities of honeysuckle powder were 93.65 ± 9.36% (DPPH radical scavenging), 91.26 ± 5.68% (•OH radical scavenging), and 1.96 ± 0.06 (Total reducing power), respectively. The effect of the addition of honeysuckle powder on the antioxidant activity of the bread is shown in

Table 4. The effects of the addition of honeysuckle powder on the antioxidant and antiaging capacities of the bread.

	Honeysuckle Powder Addition/%
	0	1	2	3	4	5	6	7
DPPH radical scavenging (%)	73.52 ± 4.36 e	79.41 ± 5.35 d	81.35 ± 3.64 c	84.43 ± 3.36 b	86.05 ± 6.45 a	86.45 ± 5.73 a	86.63 ± 7.94 a	86.98 ± 4.54 a
•OH radical scavenging (%)	65.56 ± 6.46 e	70.37 ± 3.56 d	72.35 ± 4.25 c	75.65 ± 4.57 b	81.45 ± 7.23 a	81.44 ± 4.63 a	80.67 ± 5.74 a	80.85 ± 4.36 a
Total reducing power	1.33 ± 0.15 e	1.45 ± 0.07 d	1.53 ± 0.56 c	1.68 ± 0.11 b	1.82 ± 0.07 a	1.85 ± 0.08 a	1.86 ± 0.04 a	1.84 ± 0.04 a
Aging degree (g/min)	0.32 ± 0.07 a	0.29 ± 0.05 b	0.25 ± 0.11 c	0.18 ± 0.04 d	0.08 ± 0.02 e	0.07 ± 0.03 e	0.06 ± 0.02 e	0.05 ± 0.04 e

Note: Different lowercase letters in the same line indicate a significant difference (p < 0.05), while the same lowercase letters indicate no significant difference (p > 0.05).

. The increase in the antioxidant activity of the bread slowed after adding more than 4% honeysuckle powder, which indicated that 4% honeysuckle powder was the best addition. The results showed that adding honeysuckle powder could improve the antioxidant activity of the bread and give the bread a higher nutritional value.

3.6. The Effect of the Addition of Honeysuckle Powder on the Antiaging Activity of the Bread

The addition of honeysuckle powder to wholegrain flour significantly reduced the aging degree of the bread (p < 0.05) (Table 4). The dietary fiber in the honeysuckle competed for water with other components in the dough; thus, the aging degree of the bread was reduced. In addition, the honeysuckle had good water retention [29], which hindered the diffusion of water to a certain extent and also reduced the aging of the bread during storage. When the content of the honeysuckle powder was more than 4%, the antiaging activity of the bread had no significant change.

4. Discussion

Honeysuckle powder was added to whole wheat flour to form reconstituted cereal flour. After mixed fermentation with yeast and Lactobacillus plantarum, the fermentation characteristics of the dough improved significantly, the formation of the disulfide bonds in the gluten protein was promoted, and some phytic acid and tannin antinutrients were degraded to increase the nutrition of the dough and greatly improve the quality of the bread [30]. The soluble dietary fiber in the honeysuckle flour might have a strong water-holding capacity and thus absorbed water and expanded, which made the dough’s hygroscopicity higher and promoted the elastic strength of the gluten [6,31]. When the protein content was constant, the hardness and the chewiness of the bread were strengthened with the increase in the gluten content. Glutenin is one of the main components of gluten, which contains intramolecular disulfide bonds and intermolecular disulfide bonds. A disulfide bond plays an important role in the formation of the gluten network structure, the maintenance of gluten stability, and the rheological properties of dough, as well as gluten elasticity and extensibility. It may be that an excessive addition of honeysuckle powder leads to the destruction of gluten, which exposes the starch granules outside the gluten network structure, thus reducing the stability of the gluten and the elasticity of the bread [28]. The antioxidant activity of the bread gradually increased with the increase in the amount of honeysuckle powder, which was due to the phenolic substances in the honeysuckle powder that had strong antioxidant activity. The increase in the antioxidant activity increased the functional properties of the bread, which can play a role in scavenging free radicals and delaying aging. The content of the phenolic substances in the reconstituted cereal flour increased, and Pang [31] showed that phenolic substances could retain most of their antioxidant activity when baked at a high temperature; so, the antioxidant activity of the bread was improved.

The mixed fermentation of the honeysuckle cereal mixed flour with yeast and lactic acid bacteria significantly improved the quality of the bread and prolonged the shelf life of the bread. With the increase in the honeysuckle powder content, the storage modulus and loss modulus of the fermented dough gradually increased, and the solid properties of the dough increased. When the content of the honeysuckle powder was 0~4%, the hardness, chewiness, and recovery of the bread decreased, but the elasticity, antioxidant activity, and antiaging activity of the bread increased significantly. When the content of the honeysuckle powder was in the range of 4~7%, the hardness, elasticity of bread, antioxidant activity, and antiaging activity had no significant change. According to the rheological properties of the dough, the texture, color, sensory analysis, and antioxidant capacity of bread, the flavor of the bread with 4% honeysuckle powder added to the whole grain flour was optimal, and the comprehensive score was the highest. The application of the mixed bacteria fermented honeysuckle cereal mixed flour in bread making not only provides consumers with a healthier and more nutritious food but also provides a new idea for the development of functional food.

5. Conclusions

Using mixed yeast and lactic acid bacteria to ferment honeysuckle cereal mixed flour to make bread significantly improved the quality, shelf life, and functional characteristics of the bread. Based on the results of the rheological properties of the dough, the texture, color, sensory, antioxidant activity, and antiaging activity of the bread, the highest bread quality was achieved when the content of honeysuckle powder was 4%. Adding honeysuckle powder to baked goods therefore represents a nutritionally effective strategy and a significant step forward to increase the consumption of honeysuckle.