Insight into konjac glucomannan-retarding deterioration of steamed bread during frozen storage: Quality characteristics, water status, multi-scale structure, and flavor compounds
了解魔芋葡甘露聚糖在冷冻贮藏过程中的延缓劣变质：品质特性、水分状态、多尺度结构和风味化合物

Konjac glucomannan 魔芋葡甘露聚糖
Steamed bread 馒头
Frozen storage 冷冻储存
Quality 质量
Flavor compounds 风味化合物

Steamed bread holds a special place as a cherished fermented staple across various cultures, offering a multitude of health benefits. Beyond simply satisfying hunger, it supports gastrointestinal health and aids digestion, facilitating the absorption of vital nutrients such as calcium, magnesium, and iron. In response to evolving consumer preferences, functional variations of steamed bread fortified with probiotics and dietary fiber have emerged. However, despite its nutritional richness, traditional steamed bread faces challenges in large-scale industrial production due to its perishable nature, stemming from its high water content (Qian, Gu, Sun, & Wang, 2021). Balancing the preservation of its nutritional value with extending its shelf life presents a complex challenge for manufacturers. As such, innovative solutions are continually sought to meet consumer demand for both healthy and convenient food options.
馒头在各种文化中作为珍贵的发酵主食，具有特殊的地位，具有多种健康益处。除了满足饥饿感外，它还支持胃肠道健康并帮助消化，促进钙、镁和铁等重要营养物质的吸收。为了响应不断变化的消费者偏好，出现了用益生菌和膳食纤维强化的馒头的功能变化。然而，尽管营养丰富，传统的蒸面包由于其高含水量而易腐烂，在大规模工业生产中面临挑战，这源于其高水分含量（Qian， Gu， Sun， & Wang， 2021）。在保持其营养价值与延长其保质期之间取得平衡，对制造商来说是一个复杂的挑战。因此，不断寻求创新解决方案，以满足消费者对健康和方便食品选择的需求。

To address this challenge, freezing technology has been embraced to manufacture frozen products. This innovation has elevated frozen steamed bread to a prominent position among supermarket offerings due to its extended shelf life, convenience, and adherence to stringent safety standards (Zhu, 2021; Qian et al., 2021). However, freezing and frozen storage can lead to quality deterioration in frozen steamed bread, manifesting as increased hardness, reduced specific volume, and damage to its microstructure (Qian et al., 2022; Gao, Zeng, Qin, Zeng, & Wang, 2023). Frozen storage significantly altered the aggregation and structural properties of heat-denatured gluten proteins in steamed bread (Qian et al., 2021). Another study reported that amylopectin extracted from frozen steamed bread exhibited decreased fractions of B1 and B2 chains, while the long B3 chains and average chain length increased (Deng, Zhang, Ren, Song, & Zhao, 2023). Additionally, the addition of gluten alleviated the deterioration of specific volume, hardness, and microstructure qualities of fast-frozen steamed bread during frozen storage (Qian et al., 2022). The decline of steamed bread quality is primarily due to alterations in water content, starch properties, and gluten networks throughout frozen storage (Qian et al., 2022; Deng et al., 2023). Water undergoes migration and redistribution within the dough, while recrystallization of ice crystals disrupts the starch-gluten matrix (Gao et al., 2023). Moreover, starch degradation and recrystallization of branched starch further contribute to these changes (Kou et al., 2019). To maintain a competitive edge in the market, continual
为了应对这一挑战，冷冻技术已被用于制造冷冻产品。这项创新使冷冻馒头在超市产品中占据了突出地位，因为它延长了保质期、方便并遵守严格的安全标准（Zhu，2021 年;Qian et al.， 2021）。然而，冷冻和冷冻储存会导致冷冻馒头的质量下降，表现为硬度增加、比容降低和微观结构受损（Qian et al.， 2022;Gao， Zeng， Qin， Zeng， & Wang， 2023）。冷冻储存显着改变了馒头中热变性面筋蛋白的聚集和结构特性（Qian et al.， 2021）。另一项研究报告称，从冷冻馒头中提取的支链淀粉表现出 B1 和 B2 链的分数减少，而长 B3 链和平均链长增加（邓、张、任、宋和赵，2023 年）。此外，面筋的添加缓解了速冻馒头在冷冻储存过程中比体积、硬度和微观结构品质的恶化（Qian et al.， 2022）。馒头质量的下降主要是由于整个冷冻储存过程中水分含量、淀粉特性和面筋网络的变化（Qian 等人，2022 年;邓等人，2023 年）。水在面团内发生迁移和重新分布，而冰晶的再结晶破坏了淀粉-面筋基质（Gao等人，2023 年）。此外，淀粉降解和支链淀粉的再结晶进一步促进了这些变化（Kou et al.， 2019）。为了在市场上保持竞争优势，持续

improvement of frozen steamed bread quality is essential to meeting the evolving expectations of consumers.
提高冷冻馒头的质量对于满足消费者不断变化的期望至关重要。

Significant research efforts have been dedicated to enhancing frozen product quality in recent years. Hydrocolloids have emerged as a promising solution, effectively mitigating the deterioration of frozen dough and its resultant product (Tekle, Ozulku, Bekiroglu, & Sagdic, 2023; He et al., 2020). Their notable water-holding capacity plays a crucial role in inhibiting water migration within frozen flour products during storage. This is achieved by strengthening the coactions between starch and gluten granules while simultaneously reducing the water activity of the products by competing for water with proteins and starch. Studies have demonstrated that guar gum (Hejrani, Sheikholeslami, Mortazavi, & Davoodi, 2017), carboxymethyl cellulose sodium (Xin, Nie, Chen, Li, & Li, 2018), and chitooligosaccharides (Jiang, Guo, Xing, & Zhu, 2023) can enhance the specific volume of frozen dough products while reducing their hardness. In one study, hydroxypropyl methyl cellulose stabilized the gluten network, thereby inhabiting the transition from unfreezable to freezable water (Xuan et al., 2017). In summary, these investigations collectively underscore the robust protective effects of these hydrocolloids on frozen dough. Their primary mechanisms involve mitigating the impact of frozen treatments on water mobility and stabilizing the structure of the gluten network.
近年来，人们致力于提高冷冻产品质量的大量研究工作。亲水胶体已成为一种有前途的解决方案，有效地减轻了冷冻面团及其结果产品的恶化（Tekle， Ozulku， Bekiroglu， & Sagdic， 2023;He et al.， 2020）。它们显着的持水能力在抑制冷冻面粉产品在储存过程中的水分迁移方面起着至关重要的作用。这是通过加强淀粉和面筋颗粒之间的相互作用来实现的，同时通过与蛋白质和淀粉竞争水分来降低产品的水分活度。研究表明，瓜尔豆胶（Hejrani、Sheikholeslami、Mortazavi 和 Davoodi，2017 年）、羧甲基纤维素钠（Xin、Nie、Chen、Li 和 Li，2018 年）和壳寡糖（江、郭、邢和朱，2023 年）可以提高冷冻面团产品的比体积，同时降低其硬度。在一项研究中，羟丙基甲基纤维素稳定了面筋网络，从而存在于从不可冻结到可冻结水的过渡中（Xuan et al.， 2017）。总之，这些研究共同强调了这些亲水胶体对冷冻面团的强大保护作用。它们的主要机制包括减轻冷冻处理对水流动性的影响和稳定面筋网络的结构。

Konjac glucomannan (KGM) is a primary constituent of hemicellulose found in its cell walls (Ye, Zongo, Shah, Li, & Li, 2021). This heteropolysaccharide consists of D-glucose and D-mannose units, characterized by a distinctive hydrogen bond network, spiral structure, and topological arrangement (Shen & Li, 2022; He et al., 2020). KGM has been approved as a food additive by the U.S. Food and Drug Administration and has been recognized as safe for consumption since 1994 (Behera & Ray, 2017). While KGM is not digestible by human enzymes, it can be fermented by specific gut bacteria, particularly bifidobacteria and lactobacilli. These bacteria break down KGM into shortchain fatty acids, such as butyrate, propionate, and acetate, which are beneficial for gut health (Devaraj, Reddy, & Xu, 2019). KGM has also been shown to have protective effects against colitis by regulating the intestinal immune response and modulating the gut microbiota (Xia et al., 2023; Li, Liu, Fu, Yang, & Wu, 2024). Beyond its health benefits, KGM also enhances the quality of steamed bread. In one study, KGM significantly increased specific volume, improved whiteness, and reduced the hardness of steamed bread by influencing the state and distribution of water in frozen dough (He et al., 2020). Additionally, the incorporation of KGM not only improved the sensory qualities of steamed bread but also provided a valuable source of dietary fiber (Guo et al., 2022). Moreover, adding 0.8 % KGM dramatically reduced the staling rate by delaying the increase in hardness during storage (Sim, Aziah, & Cheng, 2011). In our research, KGM increased the bound water (He et al., 2020) and enhanced the structural stability of dough (Guo et al., 2022). Additionally, it aided in preserving the integrity of wheat starch (Guo, Wang, Liu, & Wang, 2021b), improving thermally stable properties of frozen gluten and gliadin (Guo et al., 2021a). These findings suggest that KGM holds promise for enhancing the quality of wheatbased foods. Building upon this foundation, we hypothesize that KGM may alter water distribution and improve protein and starch properties in frozen steamed bread, thereby augmenting its overall quality.
魔芋葡甘露聚糖（KGM）是其细胞壁中发现的半纤维素的主要成分（Ye， Zongo， Shah， Li， & Li， 2021）。这种异多糖由 D-葡萄糖和 D-甘露糖单元组成，其特征是独特的氢键网络、螺旋结构和拓扑排列（Shen & Li，2022 年;He et al.， 2020）。KGM已被美国食品和药物管理局批准为食品添加剂，并且自1994年以来一直被认为是安全的食用产品（Behera & Ray，2017）。虽然 KGM 不能被人类酶消化，但它可以被特定的肠道细菌发酵，特别是双歧杆菌和乳酸杆菌。这些细菌将KGM分解成短链脂肪酸，如丁酸盐、丙酸盐和乙酸盐，这些对肠道健康有益（Devaraj， Reddy， & Xu， 2019）。KGM 还被证明通过调节肠道免疫反应和调节肠道微生物群对结肠炎具有保护作用（Xia et al.， 2023;Li， Liu， Fu， Yang， & Wu， 2024）。除了健康益处外，KGM 还可以提高馒头的品质。在一项研究中，KGM 通过影响冷冻面团中水分的状态和分布，显着增加比容、提高白度并降低馒头的硬度（He et al.， 2020）。此外，KGM 的加入不仅改善了馒头的感官品质，而且还提供了宝贵的膳食纤维来源（Guo et al.， 2022）。此外，添加0.8% KGM可以显著降低老化率，从而延迟储存过程中硬度的增加（Sim， Aziah， & Cheng， 2011）。在我们的研究中，KGM 增加了结合水（He et al.， 2020）并增强了面团的结构稳定性（Guo et al.， 2022）。 此外，它还有助于保持小麦淀粉的完整性（Guo， Wang， Liu， & Wang， 2021b），改善冷冻面筋和醇溶蛋白的热稳定性（Guo et al.， 2021a）。这些发现表明，KGM 有望提高小麦食品的质量。在此基础上，我们假设 KGM 可能会改变冷冻馒头中的水分分布并改善蛋白质和淀粉特性，从而提高其整体质量。

Up to now, research has primarily concentrated on evaluating the influence of KGM on the attributes of frozen dough and the resulting steamed bread quality. However, there remains a gap in understanding how KGM comprehensively influences the frozen storage characteristics of steamed bread. This study aims to bridge this gap by investigating the impact of KGM on various quality parameters of steamed bread, including water content, starch retrogradation, and overall quality characteristics. Additionally, we examine the microstructural changes in steamed bread incorporating KGM during frozen storage. Furthermore, PCA analysis is performed to elucidate the relationship between KGM and the behavior of steamed bread throughout frozen storage. These findings not only provide a deeper understanding of KGM's role in frozen steamed bread but also highlight its potential applications in the industrial manufacture of frozen steamed bread.
到目前为止，研究主要集中在评估 KGM 对冷冻面团属性和由此产生的馒头质量的影响。然而，在理解 KGM 如何全面影响馒头的冷冻储存特性方面仍然存在差距。本研究旨在通过调查 KGM 对馒头各种质量参数的影响来弥合这一差距，包括含水量、淀粉回生和整体质量特性。此外，我们研究了冷冻储存过程中含有 KGM 的馒头的微观结构变化。此外，进行 PCA 分析以阐明 KGM 与馒头在整个冷冻储存过程中的行为之间的关系。这些发现不仅提供了对 KGM 在冷冻馒头中的作用的更深入理解，还突出了它在冷冻馒头工业制造中的潜在应用。

Plain wheat flour with a composition of water, 100 g ash, protein, and starch (dry basis) was supplied by Xiangnian Flour Co., Ltd. (Nanyang, Henan, China). Konjac glucomannan (Model: KJ36, viscosity 36,000 Pa s, and purity 95 %) was obtained from Hubei Jansen Konjac Technology Co., Ltd. (Wuhan, Hubei, China). Active dry yeast was presented from Angel Yeast Co., Ltd. (Yichang, Hubei, China). Glycine, trichloroacetic acid, and mercaptoethanol were obtained from Aladdin Biotechnology Co., Ltd. (Xi'an, Shaanxi, China). All chemicals were of analytical grade in the study.
由 水、 100 克灰分、 蛋白质和 淀粉（干基）组成的普通小麦粉由湘年面粉有限公司（中国河南省南阳市）提供。魔芋葡甘露聚糖（型号：KJ36，粘度 36,000 Pas，纯度 95%）购自湖北詹森魔芋科技有限公司（中国湖北省武汉市）。活性干酵母由 Angel Yeast Co.， Ltd.（中国湖北省宜昌市）推出。甘氨酸、三氯乙酸和巯基乙醇购自阿拉丁生物科技有限公司（中国陕西省习安市）。在研究中，所有化学品均属于分析级。

The flour ( 300 g ) was substituted with varying proportions of KGM ( , and w/w), determined through preliminary trials. The resulting blends were subjected to farinograph analysis using a model JFZD Farinograph-E (Dong Fu Jiu Cheng Instrument Technology Co., Ltd., Beijing, China) following the standard AACC Method (AACC, 2010a). Water was added incrementally until the dough reached its maximum consistency of . The water absorption, dough development time, and dough stabilization time were obtained. Three replications of the test were performed.
面粉 （ 300 g ） 用不同比例的 KGM （ 和 w/w） 代替，通过初步试验确定。按照标准 AACC 方法 （AACC， 2010a），使用模型 JFZD Farinograph-E（东福久程仪表科技有限公司，中国北京）对所得混合物进行粉蛋白分析。逐渐加水，直到面团达到其最大稠度 。获得吸水率、面团发展时间和面团稳定时间。进行了三次重复测试。

The foundational recipe for the steamed bread comprised 100 g of wheat flour, 0.8 g of dry yeast, and deionized water. Based on the water absorption, , and 62.0 mL of water were added to the flour with , and KGM content, respectively. Before mixing, the dry yeast was dispersed in distilled water and activated at for 4 min . All ingredients in each formulation were combined in a mode HM740 kneader (Qingdao Hanshang Electric Co., Ltd., Qingdao, Shandong, China) at 50 rpm for 4 min and at 100 rpm for 5 min until gluten formation was complete. The formed dough was cut into 50 g pieces, molded, and proofed in a model FJX-16 fermentation bin (Demashi Instrument Co., Ltd., Guangzhou, Guangdong, China) at for 45 min . Next, the primary fermented dough was deflated, reshaped, and allowed to ferment for an additional 15 min . Finally, the secondary fermented dough was steamed for 18 min and cooled at for 1 h . One portion of the steamed bread was directly analyzed, while the other was placed in self-sealing bags and rapidly cooled for 1 h in a refrigerator at (Qingdao Haier Zhijia Co., Ltd., Qingdao, Shandong, China). Subsequently, samples were frozen at in a model BCD-218S DA refrigerator (Qingdao Haier Co., Ltd., Qingdao, Shandong, China) for 1, 2, and 3 weeks, respectively. At designated intervals during frozen storage, one portion of the frozen samples was thawed at for 2 h , and the other was re-steamed for sensory evaluation. The sample without KGM was the control.
馒头的基本配方包括 100 克小麦粉、0.8 克干酵母和去离子水。根据吸水率， 向面粉中加入 和 62.0 mL 水，分别含有 和 KGM 含量。混合前，将干酵母分散在蒸馏水中并在 4 min 下活化 。将每种制剂中的所有成分以 HM740 捏合机（青岛汉尚电气有限公司，中国山东青岛）以 50 rpm 混合 4 分钟，并以 100 rpm 混合 5 分钟，直至面筋形成完成。将成型的面团切成 50 克小块，成型，并在 FJX-16 型发酵仓（Demashi Instrument Co.， Ltd.，中国广东广州） 中醒发 45 分钟。接下来，将初级发酵面团放气、重塑并再发酵 15 分钟。最后，将二次发酵的面团蒸 18 min，冷却 1 h。直接分析馒头的一部分，而另一部分放入自密封袋中，并在冰箱中快速冷却 1 小时 （青岛海尔智佳有限公司，中国山东省青岛市）。随后，将样品 在 BCD-218S DA 型冰箱（青岛海尔股份有限公司，中国山东青岛）中分别冷冻 1、2 和 3 周。在冷冻贮藏期间，按指定时间间隔将 一部分冷冻样品解冻 2 h，另一部分重新蒸煮进行感官评价。没有 KGM 的样品是对照。

The texture of steamed bread was examined as previously reported (Duan et al.,2024). Samples ( ) were extracted from steamed bread and meticulously wrapped in cling film to prevent water loss. Each sample was placed on the glass plate and evaluated by a model TA. XT Express Texture Analyzer (Stable Micro Systems, London, UK) with a probe (P/36R). The pre-test and test speeds were , the compression degree was , the trigger force was 0.05 N , and the post-
如前所述检查了馒头的质地（Duan et al.，2024）。从馒头中提取样品 （ ），并用保鲜膜精心包裹以防止水分流失。将每个样品放在玻璃板上，并通过 TA 模型进行评估。带探头 （P/36R） 的 XT Express 质构仪（Stable Micro Systems，英国伦敦）。前测速和测试速度为 ，压缩度为 ，触发力为 0.05 N ，后测速为
test speed was . The hardness, chewiness, springiness, and resilience were recorded. Three replications of the test were performed.
测试速度为 。记录了硬度、咀嚼性、弹性和弹性。进行了三次重复测试。

The steamed bread was cut into 12 mm thick slices and photographed for documentation. The steamed bread images were transformed to 8-bit greyscale by Image J software (NIH, Bethesda, USA) to calculate cell numbers and average gas cell sizes (Lu, Xing, Yang, Guo, & Zhu, 2021).
将蒸面包切成 12 毫米厚的薄片并拍照以备记录。通过 Image J 软件（NIH，Bethesda，USA）将馒头图像转换为 8 位灰度，以计算细胞数量和平均气体细胞大小（Lu、Xing、Yang、Guo 和 Zhu，2021 年）。

The specific volume of steamed bread frozen for 0 and 3 weeks was carried out following the previous method (Li, Guo, Lu, Yue, & Wang, 2024) and calculated by dividing the volume by the mass ( g ). The experiment was replicated three times.
按照前一种方法（Li， Guo， Lu， Yue， & Wang， 2024）进行冷冻0周和3周的蒸面包的特定体积，并通过将体积 除以质量（g）来计算。该实验重复了 3 次。

The sensory evaluation of steamed bread was performed by 20 trained assessors from Henan University of Science and Technology, following the method (Zhao et al., 2021) with some modifications. Before sensory assessment, the samples were re-steamed for 10 min . During evaluation, both whole steamed bread and approximately 10 g portions ( ) were presented to the panelists on disposable white plates, each labeled with a random 3-digit code to ensure anonymity. Samples were presented in a random order for duplicate quantification, and panelists individually scored various sensory attributes on a scale from 0 to 10 , utilizing predefined criteria standards (Table S1). To minimize the cross-sample influence, a oneminute interval was observed between tastings, and panelists were provided with filtered water to cleanse their palates. All evaluations took place in sensory laboratories maintained at suitable temperatures. The total score comprised assessments across five aspects: appearance, structure, toughness, stickiness, and aroma.
馒头的感官评价由河南科技大学的 20 名训练有素的评估员按照该方法（Zhao et al.， 2021）进行，并进行了一些修改。在感官评估之前，将样品重新蒸 10 分钟。在评估过程中，整个馒头和大约 10 克的份量 （ ） 都放在一次性白色盘子上呈现给小组成员，每个盘子都标有随机的 3 位代码以确保匿名。样品以随机顺序呈现以进行重复量化，小组成员使用预定义的标准标准（表 S1）以 0 到 10 的等级对各种感官属性进行单独评分。为了尽量减少交叉样品的影响，在品酒之间间隔一分钟，并为小组成员提供过滤水以清洁他们的味觉。所有评估均在保持适当温度的感官实验室中进行。总分包括外观、结构、韧性、粘性和香气五个方面的评估。

About 1.5 g of sample was cut from steamed bread, placed on empty plates, and dried in a model DHG-9040C drying oven (Hangzhou Blue Sky Instrument Co., Ltd., Hangzhou, Zhejiang, China) at until a constant weight was reached, following the standard method (AACC, 2010b). The water content ( , w/w) was calculated by dividing the mass change ( g ) of the sample after drying by the mass of the sample before drying. The average value for the three subsamples was recorded.
从馒头上切下约 1.5 g 样品，放在空盘子上，并在 DHG-9040C 型干燥箱（杭州蓝天仪器有限公司，中国浙江省杭州市）中干燥， 直至达到恒定重量，遵循标准方法（AACC，2010b）。水分含量 （ ， w/w） 的计算方法是将干燥后样品的质量变化 （ g ） 除以干燥前的样品质量 。记录 3 个子样本的平均值。

The water distribution within steamed bread was assessed as previously described (He et al., 2020). About 1 g of sample was cut from steamed bread, carefully placed into an NMR bottle, and tightly compacted to remove any voids. Subsequently, the NMR bottle containing the sample was inserted into NMR test tubes and analyzed using a model NM120-015V-1 low-field NMR spectrometer (Neumay Electronic Technology Co., Ltd., Shanghai, China). The relaxation time was measured by specific parameters: a frequency of 200 kHz , an interval time of 3500 ms , and a cumulative number of times of 16 . The percentages of bound water, weakly bound water, and free water were recorded. The average of three measurements was taken.
如前所述评估了馒头内的水分分布（He et al.， 2020）。从蒸面包上切下约 1 g 样品，小心地放入 NMR 瓶中，并紧密压实以去除任何空隙。随后，将装有样品的 NMR 瓶插入 NMR 试管中，并使用 NM120-015V-1 型低场 NMR 波谱仪（Neumay Electronic Technology Co.， Ltd.，中国上海）进行分析。弛豫时间由特定参数测量：频率 200 kHz，间隔时间为 3500 ms，累积次数为 16 次。记录结合水、弱结合水和游离水的百分比。取了三次测量的平均值。

X-ray tests were conducted using a model D-8 Advance diffractometer (Bruker Corporation, Billerica, USA) with 40 mA current and 40 kV voltage (Lalush, Bar, Zakaria, Eichler, & Shimoni, 2005). The steamed bread was first lyophilized, ground, and sifted through a 200-mesh sieve to obtain a fine powder. Steamed bread powder was carefully placed into the measurement cell, leveled using a slide, and then subjected to X- ray analysis over a range of . The X-ray diffraction was analyzed using MDI Jade 6.0 software (Materials Data Inc., Livermore, California, USA).
使用D-8型高级衍射仪（Bruker Corporation，Billerica，USA）进行X射线测试，电流为40 mA，电压为40 kV（Lalush，Bar，Zakaria，Eichler和Shimoni，2005年）。首先将馒头冻干、磨碎并通过 200 目筛子过筛以获得细粉。将蒸面包粉小心地放入测量池中，使用载玻片调平，然后在 . 使用 MDI Jade 6.0 软件（Materials Data Inc.，Livermore，California，USA）分析 X 射线衍射。

The infrared spectra of steamed bread were recorded as previously described (Pan et al., 2019). The KBr was combined with steamed bread powder in a mortar at a ratio of , ground for 10 min , and then compressed by a tablet press at 16 MPa pressure for 60 s to produce transparent tablets. The peak spectra of the steamed bread powder were analyzed utilizing a model VERTEX70 FT-IR spectroscopy (Bruker Corporation, Lucken, Germany) with 64 scans at a resolution of . The and 995/1022 were performed by OMNIC software (version 8.2, Thermo Nicolet Corp.).
如前所述记录馒头的红外光谱（Pan等人，2019 年）。将 KBr 与蒸面包粉在研钵中按比例混合 ，研磨 10 min，然后用压片机在 16 MPa 压力下压制 60 s，制成透明片剂。使用 FT-IR 光谱模型（Bruker Corporation，Lucken，Germany）分析蒸面包粉的峰光谱，VERTEX70 64 次扫描，分辨率为 。和 995/1022 由 OMNIC 软件（8.2 版，Thermo Nicolet Corp.）执行。

The free sulfhydryl content of samples was analyzed as previously described with minor modifications (Guan, Zhang, Wu, Yang, & Bian, 2023). Approximately 75 mg of steamed bread and 4.7 g of guanidine hydrochloride were added to a 1 mL Tris-glycine buffer ( Tris, 6.9 g glycine, 1.2 g EDTA) and fixed to 10 mL with buffer solution. Subsequently, 2 mL of the prepared solution, 1 mL of Ellman's reagent, and 8 mL of urea-guanidine hydrochloride solution were mixed. This mixture was reacted for 1 h at . Next, the sample solution was transferred to a cuvette, and the absorbance of the sample was measured at 412 nm by a model UV-2600 spectrophotometer (Shimadzu Corporation, Kyoto, Japan). Free sulfhydryl content ( ) was calculated using Eq. (1):
如前所述，对样品的游离巯基含量进行了分析，并进行了微小的修改（Guan， Zhang， Wu， Yang， & Bian， 2023）。将大约 75 mg 馒头和 4.7 g 盐酸胍加入 1 mL Tris-甘氨酸缓冲液（ Tris、6.9 g 甘氨酸、1.2 g EDTA）中，并用缓冲溶液固定至 10 mL。随后，将 2 mL 制备的溶液、1 mL Ellman 试剂和 8 mL 尿素-盐酸胍溶液混合。该混合物在 中反应 1 小时。接下来，将样品溶液转移至比色皿中，并通过 UV-2600 型分光光度计（Shimadzu Corporation，日本京都）在 412 nm 处测量样品的吸光度。游离巯基含量 （ ） 使用方程 （1） 计算：

Where, 73.53 is the extinction coefficient; is the absorbance at is the dilution factor; is the sample concentration ( ).
其中，73.53 是消光系数; 是吸光度 是稀释因子; 是样品浓度 （ ）。

The steamed bread sample was fractured into pieces 1 cm ) to expose the interior structure after being frozen for 0 or 3 weeks (Qian et al., 2022). These fractured pieces were then dehydrated using a model LGJ-10D freeze dryer (Sihuan Scientific Instrument Co., Ltd., Beijing, China). Subsequently, the dehydrated samples were sprayed with gold about 12 nm in thickness using a model EM ACE200 gold sprayer (Leica Camera Corporation, Hesse, Germany). The microstructure of samples was measured by a model TM3030 Plus SEM (Hitachi Corporation, Mito, Japan) with magnifications of and , respectively.
将馒头样品冷冻 0 或 3 周后碎成 1 厘米的碎片 ），露出内部结构（Qian et al.， 2022）。然后使用 LGJ-10D 型冷冻干燥机（四环科学仪器有限公司，中国北京）对这些断裂的碎片进行脱水。随后，使用 EM ACE12 型金喷雾器（徕卡相机公司，黑森州，德国）用约 200 nm 厚的金喷涂脱水样品。样品的微观结构由型号 TM3030 Plus SEM （Hitachi Corporation， Mito， Japan） 测量，放大倍数分别为 和 。

The volatile compounds of the samples were measured using a model TSQ 9000 gas chromatography-mass spectrometry (Thermo Scientific, Massachusetts, USA) as previously described (Ma, Mu, & Zhou, 2021) with some modifications. About 2 g of steamed bread and 2-methyl3-heptanone were put in a 20 mL headspace. A Solid Phase Microextraction fiber was inserted into the headspace and extracted volatiles at a water bath of for 55 min . Next, the fiber was promptly put into the injection port of the gas chromatograph to desorb the compounds at for 5 min . Volatiles were separated on an HP-5MS capillary column ( ) with a helium flow rate of . The GC oven temperature was programmed from (hold for 4 min ) to (hold for 12 min ) at a rate of . The transfer line and ion source temperatures were 280 and , respectively. The scan mode was between 35 and . Compound identification was performed by comparing mass spectrometry data with the National Institute of Standards and Technology
如前所述（马、Mu 和 周，2021 年），使用型号 TSQ 9000 气相色谱-质谱法（Thermo Scientific，美国马萨诸塞州）测量样品的挥发性化合物，并进行了一些修改。将约 2 g 馒头和 2-甲基 3-庚酮放入 20 mL 顶部空间。将固相微萃取纤维 头插入顶部空间，并在 55 分钟的水浴 中萃取挥发物。接下来，立即将纤维头放入气相色谱仪的进样口，以 5 min 解吸化合物 。挥发物在 HP-5MS 毛细管柱 （ ） 上分离，氦流速为 。GC 柱温箱温度以 的速率从 （保持 4 分钟） 编程为 （保持 12 分钟）。传输线和离子源温度分别为 280 和 。扫描模式介于 35 和 之间。通过将质谱数据与美国国家标准与技术研究院 （National Institute of Standards and Technology） 进行比较来进行化合物鉴定
database. The content ( ) of volatile flavor compounds was calculated using Eq. (2):
数据库。挥发性风味化合物的含量 （ ） 使用方程 （2） 计算：

Where is the content ( ) of the compound; is the mass concentration of the internal standard content; is the volume ( ) of internal standard injection; is the peak area of the compound; is the peak area of the internal standard substance; is the sample quality .
其中 是化合物的含量 （ ）; 是内标含量的质量浓度 ; 是内标进样的体积 （ ）; 是化合物的峰面积 ; 是内标物质的峰面积 ; 是样本质量 。

The results were expressed as means standard deviation. Statistical analysis was performed by a one-way analysis of variance followed by Duncan's multiple range test ( ) and independent-samples -test using SPSS 20.0 software (SPSS Inc., Chicago, IL, USA). Graphs were drawn using Origin Software 2021 (Origin Lab Corp., MA, USA).
结果表示为均值 标准差。通过使用 SPSS 20.0 软件 （SPSS Inc.， Chicago， IL， USA） 进行单因素方差分析，然后进行 Duncan 多范围检验 （ ） 和独立样本 检验。图表是使用 Origin Software 2021（Origin Lab Corp.，MA，USA）绘制的。

Farinographic properties are indeed crucial for evaluating wheat flour quality. Flour's strength and water absorption capacity are key factors in determining its suitability for various applications. These properties provide valuable insights into the behavior of flour during processing, helping manufacturers optimize formulations and processes to achieve desired product attributes. The farinographic properties of flour with KGM are illustrated in Fig. 1. Water absorption (WA) indicates the amount of water needed to achieve the desired dough consistency of 500 FU . The WA of the flour with different KGM additions increased in the order of control (Fig. 1a). At the replacement level of , the WA of the dough increased by compared with the control. This indicates that more water is absorbed in the presence of KGM to achieve the desired dough consistency of 500 FU . This is because KGM, with its polyhydroxy structure, has a higher water-binding capacity than gluten (Sim et al., 2011). In one study, the water absorption of dough increased with the rising substitution levels and viscosity of KGM (Guo et al., 2022). Similarly, another study found that dough containing KGM exhibited a higher level of water absorption compared with the control (Meng et al., 2021).
粉学特性对于评估小麦粉质量确实至关重要。面粉的强度和吸水能力是决定其适用于各种应用的关键因素。这些特性为面粉在加工过程中的行为提供了有价值的见解，帮助制造商优化配方和工艺以实现所需的产品属性。含 KGM 的面粉的粉学特性如图 1 所示。吸水率 （WA） 表示达到所需的面团稠度 500 FU 所需的水量。添加不同 KGM 的面粉的 WA 按 对照顺序增加（图 1a）。在 的更换水平 ，与对照 相比，面团的 WA 增加。这表明在 KGM 存在下吸收了更多的水，以达到所需的 500 FU 面团稠度。这是因为 KGM 具有多羟基结构，比面筋具有更高的水结合能力（Sim et al.， 2011）。在一项研究中，面团的吸水率随着 KGM 取代水平和粘度的升高而增加（Guo et al.， 2022）。同样，另一项研究发现，与对照组相比，含有 KGM 的面团表现出更高水平的吸水率（Meng et al.， 2021）。

Dough development time (DDT) refers to the period from the addition of water until the farinograph curve reaches its peak consistency, marking the time required for water to fully interact with the flour and for the dough to form. The DDT values in wheat-KGM blends were obviously higher than those in the control (Fig. 1b), indicating an extended time to reach maximum dough consistency. This finding implies that KGM molecules compete against gluten for water, and therefore affect the development of gluten network due to the swelling of hydrocolloids (Li et al., 2019). In one study, adding bran increased the DDT in low-gluten flour but decreased it in medium and high-gluten flour (Li et al., 2023). This inconsistency could be partially
面团形成时间 （DDT） 是指从加水到粉质曲线达到其峰值稠度的时间，标志着水与面粉充分相互作用和面团形成所需的时间。小麦-KGM 混合物中的 DDT 值明显 高于对照中的 DDT 值（图 1b），表明达到最大面团稠度的时间延长。这一发现意味着 KGM 分子与面筋竞争水，因此由于亲水胶体的膨胀而影响面筋网络的发展（Li et al.， 2019）。在一项研究中，添加麸皮会增加低筋面粉中的 DDT，但会降低中高筋面粉中的 DDT（Li 等人，2023 年）。这种不一致可能是部分的

Fig. 1. Water absorption (a), dough development time (b), and stability time (c) of wheat flours added with different additions of konjac glucomannan (KGM). Different lower case letters represent significant ( ) differences among steamed bread with different KGM additions.
图 1.添加不同添加量魔芋葡甘聚糖 （KGM） 的小麦粉的吸水率 （a）、面团形成时间 （b） 和稳定时间 （c）。不同的小写字母表示添加不同 KGM 的馒头之间的显著 （ ） 差异。
attributed to variations in gluten content within the flour. Another reason might be the diverse starch compositions, which influence the mixing properties of the dough (Li et al., 2021).
归因于面粉中面筋含量的变化。另一个原因可能是淀粉成分的多样性，这会影响面团的混合特性（Li et al.， 2021）。

The stability time (ST) characterizes its resistance to kneading, with higher values indicating stronger gluten and more elastic dough ( Yu et al., 2019). Adding KGM dramatically ( ) reduced the ST value in the dough, and this decline in ST corresponded with the escalation in KGM levels (Fig. 1c). This is because KGM causes steric hindrance, dilutes the gluten, or even punctures gas cells, thereby impacting gluten development. Another reason is that KGM decreases the overall rigidity of the dough.
稳定时间 （ST） 表征了其抗揉捏性，较高的值表示面筋更强，面团更有弹性（Yu et al.， 2019）。添加 KGM 显着降低了面团中的 ST 值 （ ），ST 的下降与 KGM 水平的升高相对应（图 1c）。这是因为 KGM 会引起空间位阻，稀释面筋，甚至刺穿气室，从而影响面筋的形成。另一个原因是 KGM 降低了面团的整体刚度。

In summary, as the amount of KGM increases, water absorption increases, dough development time initially rises and then declines, while stabilization time decreases in wheat-KGM blends.
综上所述，随着 KGM 量的增加，吸水率增加，面团形成时间最初上升后下降，而小麦-KGM 共混物的稳定时间缩短。

High-quality steamed bread is generally associated with a larger specific volume and a more uniform cell structure, which directly influences product shape and consumer preferences. The impact of KGM on specific volume of steamed bread frozen at 0 and 3 weeks is presented in Table 1. At week 3, the specific volume of samples significantly ( 0.05 ) increased and then displayed a slight decrease as the KGM increased. The highest specific volume, which was higher than the control, was achieved with the KGM steamed bread. This increase in specific volume is related to KGM's interaction with gluten, leading to better gas retention in the gluten network (Guo et al., 2022). Meanwhile, the enhanced gas retention capacity also leads to smaller average gas cell sizes and higher cell numbers in samples, resulting in a more uniform cell structure (Table 1).
高质量的馒头通常与更大的比容和更均匀的细胞结构有关，这直接影响产品形状和消费者偏好。KGM 对 0 周和 3 周冷冻馒头比体积的影响如表 1 所示。第 3 周时，样品比体积显著增加 （ 0.05 ），然后随着 KGM 的增加而略有减少。最高的比体积 高于对照，使用 KGM 馒头实现。这种比容的增加与 KGM 与面筋的相互作用有关，导致面筋网络中更好的气体保留（Guo et al.， 2022）。同时，增强的气体保留能力还导致样品中的平均气体池尺寸更小，细胞数量更高，从而获得更均匀的细胞结构（表 1）。

Here, the pore structure of the KGM steamed bread was similar to that of the control, with large pores and a non-uniform size and distribution (Fig. 2). In contrast, steamed bread with and KGM additions exhibited no obvious large pores, and their internal structure displayed more homogeneous and dense pores compared with the control. The reason might be that KGM helps to form the desired starchgluten matrix, physically stabilizing gas cells and ensuring homogeneous expansion of air cells (Janssen, Wouters, & Delcour, 2021; Škara, Novotni, Čukelj, Smerdel, & Ćuri, 2013). At a molecular level, the mechanism through which KGM controls the stability of gas cells reduces the likelihood of coalescence among individual gas cells by forming a liquid film at the gas-liquid interface (Janssen et al., 2021; Sroan, Bean, & MacRitchie, 2009). The size and density of the gas cells can lead to significant differences in the texture and sensory characteristics of the end product (Turbin-Orger et al., 2012).
在这里， KGM 馒头的孔结构与对照相似，具有大孔和不均匀的大小和分布（图 2）。相比之下，添加 KGM 的馒头没有明显的大孔隙，其内部结构与对照相比表现出更均匀和致密的孔隙。原因可能是KGM有助于形成所需的淀粉面筋基质，物理稳定气室并确保气室的均匀膨胀（Janssen， Wouters， & Delcour， 2021; Škara， Novotni， Čukelj， Smerdel， & Ćuri， 2013）。在分子水平上，KGM 控制气室稳定性的机制通过在气液界面形成液膜来降低单个气室之间聚结的可能性（Janssen等人，2021 年;Sroan， Bean， & MacRitchie， 2009）。气室的大小和密度会导致最终产品的质地和感官特性出现显着差异（Turbin-Orger et al.， 2012）。

During frozen storage, the specific volume significantly decreased in all steamed bread groups due to the damage to the gluten network induced by the formation of ice crystals (Table 1). It may also be related to the destruction of the aggregated and molecularly ordered structure of starch (Gao et al., 2023). Notably, the decrease in a specific volume of , and KGM steamed bread was 0.15 , , and from 0 to 3 weeks, respectively. The decrease in specific volume in all KGM groups was observed to be smaller than that in the control group. The delay in the specific volume decrease might be due to less damage to the gluten network in the presence of KGM during frozen storage.
在冷冻储存过程中，由于冰晶的形成对面筋网络的破坏，所有馒头组的比容都显著降低 （表 1）。这也可能与淀粉聚集和分子有序结构的破坏有关（Gao等人，2023 年）。值得注意的是， 比容 和 KGM 馒头的比容分别减少 0.15 、 和 0 至 3 周。观察到所有 KGM 组的比容下降幅度均小于对照组。比体积减少的延迟可能是由于在冷冻储存过程中 KGM 存在的情况下对面筋网络的损害较小。

Overall, KGM demonstrates positive effects on increasing the specific volume and improving the cell structure of steamed bread. Moreover, KGM delays the decline in the specific volume, suggesting that KGM contributes to the formation or maintenance of a larger specific volume throughout frozen storage.
总体而言，KGM 对增加馒头的比容和改善馒头的细胞结构表现出积极作用。此外，KGM 延缓了比容的下降，表明 KGM 有助于在整个冷冻储存过程中形成或维持更大的比容。

Texture analysis is a useful tool for evaluating the popularity of wheat products, representing vital sensory attributes. Among them, hardness is regarded as the primary indicator of textural properties, and a smaller value of hardness usually indicates that steamed bread is fluffy and more easily accepted by consumers. The influence of KGM on the textural characteristics of steamed bread frozen at different time is shown in Table 2. At the same frozen storage time, the hardness significantly decreased and then slightly increased as the KGM increased. The samples with KGM addition had the lowest hardness ( 777.01 g , week 3), which was reduced by compared with the control. This is consistent with our previous findings that the hardness of steamed bread decreased when KGM was added (Guo et al., 2022; He et al., 2020). This is because KGM alters the conformations of gluten and gliadin, affecting the rearrangement of polypeptide chains' spatial structure by enhancing hydrophobic interactions (He et al., 2020). Additionally, KGM's polyhydroxyl structures may compete with starch and gluten for water to form hydrogen bonds, which can limit starch swelling. This competition may lead to changes in the starchgluten network and result in reduced hardness (Fu et al., 2021).
质构分析是评估小麦产品受欢迎程度的有用工具，代表了重要的感官属性。其中，硬度被视为质地特性的主要指标，硬度值越小，通常表明馒头蓬松，更容易被消费者接受。KGM 对不同时间冷冻的馒头质地特性的影响如表 2 所示。在相同的冷冻贮藏时间内，硬度随着 KGM 的增加而显著降低 后略有增加。添加 KGM 的样品硬度最低 （ 777.01 g，第 3 周），与对照 相比降低。这与我们之前的发现一致，即添加 KGM 后馒头的硬度降低（Guo et al.， 2022;He et al.， 2020）。这是因为 KGM 改变了面筋和麦醇溶蛋白的构象，通过增强疏水相互作用来影响多肽链空间结构的重排（He et al.， 2020）。此外，KGM 的多羟基结构可能与淀粉和面筋竞争水形成氢键，从而限制淀粉溶胀。这种竞争可能导致淀粉面筋网络发生变化并导致硬度降低（Fu et al.， 2021）。

Here, the hardness of all steamed bread groups increased as the frozen time increased, further confirming that the specific volume decreased (Section 3.2). The hardness of the control group increased from 758.42 to 951.37 g after being frozen for 3 weeks. This is primarily related to molecular aggregates of amylose (Deng et al., 2023) and the destruction of the gluten network structure (Gao et al., 2023). From 0 to 3 weeks, it is noticeable that the hardness in the control group increased by , while in the , and KGM groups it increased by , and , respectively. This result implies that the steamed bread with KGM addition reduces the growth rate of hardness and delays starch retrogradation. This is because KGM restricts water migration and ice recrystallization by interacting with water molecules to form intermolecular hydrogen bonds, thereby
在这里，所有馒头组的硬度都随着冷冻时间的增加而增加，进一步证实了比容减小（第 3.2 节）。对照组冷冻 3 周后硬度由 758.42 g 增加到 951.37 g。这主要与直链淀粉的分子聚集体（邓等人，2023 年）和面筋网络结构的破坏（Gao等人，2023 年）有关。从 0 到 3 周，很明显，对照组的硬度增加了 ，而在 和 KGM 组中，硬度分别增加了 、 和 。这一结果表明，添加 KGM 的馒头降低了硬度的增长速度并延缓了淀粉的回生。这是因为 KGM 通过与水分子相互作用形成分子间氢键来限制水迁移和冰再结晶，从而

Table 1 表 1
Specific volume, cell parameters, and FT-IR peak ratio characteristics of steamed bread added with different additions of konjac glucomannan (KGM) and frozen for 0 and 3 weeks.
添加不同添加量魔芋葡甘露聚糖 （KGM） 并冷冻 0 和 3 周的馒头的比体积、细胞参数和 FT-IR 峰比特征。

All data are expressed as mean standard deviation ). Different lower case letters represent significant ( ) differences among steamed bread with different KGM additions at the same frozen time. Different upper case letters indicate significant ( ) differences among steamed bread with the same KGM addition at different frozen time.
所有数据均表示为平均 标准差 ）。不同的小写字母表示在同一冷冻时间内添加不同 KGM 的馒头之间的显著 （ ） 差异。不同的大写字母表示相同 KGM 添加量的馒头在不同冷冻时间存在显著 （ ） 差异。

Fig. 2. Profiles and thresholding images of cell structure from 0 -week steamed bread added with different additions of konjac glucomannan (KGM).
图 2.添加不同添加魔芋葡甘露聚糖 （KGM） 的 0 周馒头的细胞结构剖面和阈值图像。
protecting the gluten network structure of samples (Jekle & Becker, 2012; Gao et al., 2023). Thus, adding KGM could alleviate the decline in hardness and delay the staling of steamed bread to a certain extent during frozen storage. Meanwhile, the chewiness of steamed bread showed a similar variation trend to their hardness as the KGM increased and the extension of frozen time.
保护样品的麸质网络结构（Jekle & Becker，2012;Gao等人，2023 年）。因此，添加 KGM 可以在一定程度上缓解馒头在冷冻贮存过程中的硬度下降并延缓馒头的老化。同时，随着 KGM 的增加和冷冻时间的延长，馒头的咀嚼性与其硬度呈相似的变化趋势。

As presented in Table 2, at the same frozen storage time, springiness and resilience decreased slightly as the KGM increased. However, the effects on the springiness and resilience of steamed bread were insignificant ( ), suggesting that KGM does not lead to a deterioration in springiness and resilience. For the control and KGM groups, springiness and resilience both decreased as the frozen time increased. This is primarily attributed to the mechanical damage to the gluten network (Zhu, 2021). Higher chewiness, hardness, and lower resilience indicate a worse quality of steamed bread.
如表 2 所示，在相同的冷冻贮藏时间内，随着 KGM 的增加，弹性和弹性略有下降。然而，对馒头的弹性和弹性的影响微不足道 （ ），表明 KGM 不会导致弹性和弹性的恶化。对照组和 KGM 组的弹性和弹性均随着冻结时间的增加而降低。这主要归因于面筋网络的机械损伤（Zhu，2021 年）。较高的咀嚼性、硬度和较低的弹性表明馒头的质量较差。

Combining the changes observed in specific volume, cell structure (Table 1), and texture (Table 2), we conclude that the addition of KGM results in steamed bread with the maximum specific volume, a more uniform cell structure, and the minimum hardness. This suggests that steamed bread with KGM displays high freeze stability. Furthermore, compared with the control, the increase in hardness of KGM-added samples was lower throughout frozen storage. These findings indicate that KGM delays the deterioration of steamed bread quality, suggesting that the internal network structure is less susceptible to damage by ice crystals. Additionally, it can be inferred that the quality degradation of steamed bread with KGM is alleviated to the greatest extent during frozen storage.
结合观察到的比容、细胞结构（表 1）和质地（表 2）的变化，我们得出结论，添加 KGM 可产生具有最大比容、更均匀的细胞结构和最小硬度的馒头。这表明用 KGM 制成的 馒头表现出很高的冷冻稳定性。此外，与对照相比，在整个冷冻储存过程中，添加 KGM 的样品的硬度增加较低。这些发现表明 KGM 延缓了馒头品质的恶化，表明内部网络结构不易受到冰晶的破坏。此外，可以推断，KGM 蒸煮馒头在冷冻贮藏过程中质量下降得到了最大程度的缓解。

The sensory evaluation of steamed bread with KGM addition for different frozen storage time is depicted in Fig. 3. Across all steamed bread groups, sensory evaluation indicators decreased with increasing frozen storage time. Notably, blistering occurred on the surface of steamed bread, visibly reducing its appearance and quality. Additionally, the texture of the frozen sample appeared less homogeneous compared with the unfrozen sample. In addition, the taste and aroma of the frozen, reheated sample were not as satisfactory as those of the unfrozen sample. Except for aroma, sensory evaluation indicators in the KGM groups were generally higher compared with the control group at the same frozen storage time, except for stickiness at 0 weeks and appearance at 1 week. Steamed bread with or KGM addition showed the highest sensory evaluation scores, followed by and . The aroma score of steamed bread decreased at 0 or 1 week with the KGM increase, while the aroma score increased as the KGM increased at 2 or 3 weeks. This suggests that the negative impact of freezing on the aroma of the sample is more significant than the effect of KGM on the aroma. This is because adding KGM protects the gluten network, resulting in the retention of more volatile substances.
图 3 描述了添加 KGM 的蒸包在不同冷冻贮存时间下的感官评价。在所有馒头组中，感官评价指标均随着冷冻贮藏时间的增加而降低。值得注意的是，蒸面包表面出现起泡，明显降低了其外观和质量。此外，与未冷冻样品相比，冷冻样品的质地似乎不那么均匀。此外，冷冻、再加热样品的味道和香气不如未冷冻样品令人满意。除香气外，在相同冷冻贮藏时间下，KGM 组的感官评价指标普遍高于对照组，除 0 周时粘性外，1 周时出现粘性。添加 或 KGM 的馒头感官评价得分最高，其次是 和 。馒头香气评分在 0 或 1 周随着 KGM 的增加而降低，而香气评分在 2 或 3 周随着 KGM 的增加而升高。这表明冷冻对样品香气的负面影响比 KGM 对香气的影响更显着。这是因为添加 KGM 可以保护面筋网络，从而保留更多挥发性物质。

Overall, the presence of KGM mitigates the damage inflicted by
总体而言，KGM 的存在减轻了

Table 2 表 2
Texture of steamed bread added with different additions of konjac glucomannan (KGM) at different frozen time.
在不同冷冻时间添加不同魔芋葡甘露聚糖 （KGM） 的蒸面包质地。