ORIGINAL PAPER
Impact of Flour Protein Content and Freezing Conditions on the Quality of Frozen Dough and Corresponding Steamed Bread
Turkay Kondakci1 & Judy Wenjuan Zhang1 & Weibiao Zhou1,2
Received: 25 December 2014 /Accepted: 8 June 2015 /Published online: 18 June 2015 # Springer Science+Business Media New York 2015
Abstract Frozen dough made using flour of higher protein content (9.5–11 %) had better resistance to freezing damage than those made using flour of lower protein content and resulted in steamed bread whose specific volume, form ratio and texture were closer to those of bread made from fresh dough. The effects of flour protein content and freezing conditions (freezing air temperature and air speed) on dough and steamed bread quality were investigated in this study. Compared to nonfrozen control, the freezing process caused a deterioration to gluten network as well as a decrease in yeast activity, which resulted in lower maximum dough height and less total gas production, leading to steamed bread of lower specific volume and form ratios, and increased hardness. Faster freezing rates resulted in dough with higher extensibility and a less damaged dough microstructure but led to a decrease in total gas production as yeast activity was compromised. The extreme freezing conditions of −20 °C and air speed of 0 m/s and −40 °C and air speed of 6 m/s had the poorest dough and steamed bread quality. Samples frozen at −30 °C had better form ratio of steamed bread than those frozen at −20 °C and −40 °C, while those frozen at −40 °C had the lowest specific volume. A moderate air speed of 3 m/s resulted in higher volume of total gas production and dough height, as well as better steamed bread texture.
Keywords Frozen dough . Steamed bread . Protein content . Freezing rate . Freezing temperature . Freezing air speed
Introduction While bread is commonly associated with oven and baking, steamed bread (also known as mantou or bao) is a staple food for many Asians. The main difference steamed bread has from baked bread would be the lack of a browned crust as steaming is a much gentler heat process compared to baking. Also, steamed bread has a moister and softer crumb. Besides processing, another major contributor to the difference between baked and steamed bread is that typical steamed bread recipes use low-protein flours (7.5–11 %) according to cultural and geographic diversity in China as well as the strength of different wheat cultivars (Ananingsih et al. 2013; Hou and Popper 2006; Kondakci and Zhou 2015; Zhu et al. 2001; Zhu 2014), while baked bread uses high-protein flours (12–14 %). Instead of distributing fresh bread, which declines in quality over distance and time, a central production of frozen dough allows for baking to be done at the point of sale such that bread can be sold and consumed fresh. Although steamed bread originated from northern China, it is currently a popular food in many Asian countries and becoming increasingly popular in the Western world as well. Consequently, frozen dough technology has become increasingly relevant for steamed bread production. With respects to steamed bread, a number of studies examined the effects of protein content on steamed bread quality, which was generally scored based on a system developed by Huang et al. (1996) that includes parameters such as specific volume, colour and eating quality. Lin et al. (1990) reported that a high-protein flour has more gluten to retain gas in the dough with regard to baked bread. They further recommended
เอกสารต้นฉบับ ผลกระทบของแป้งโปรตีนเนื้อหา และตรึงสภาพคุณภาพของแป้งแช่แข็งและตรงนึ่งขนมปัง Turkay Kondakci1 & Judy Wenjuan Zhang1 Weibiao Zhou1, 2 รับ: 25 2557 ธันวาคม/ยอมรับ: 8 2015 มิถุนายน/เผยแพร่ออนไลน์: 18 2015 มิถุนายน# Springer วิทยาศาสตร์ + ธุรกิจสื่อนิวยอร์ก 2015 Abstract Frozen dough made using flour of higher protein content (9.5–11 %) had better resistance to freezing damage than those made using flour of lower protein content and resulted in steamed bread whose specific volume, form ratio and texture were closer to those of bread made from fresh dough. The effects of flour protein content and freezing conditions (freezing air temperature and air speed) on dough and steamed bread quality were investigated in this study. Compared to nonfrozen control, the freezing process caused a deterioration to gluten network as well as a decrease in yeast activity, which resulted in lower maximum dough height and less total gas production, leading to steamed bread of lower specific volume and form ratios, and increased hardness. Faster freezing rates resulted in dough with higher extensibility and a less damaged dough microstructure but led to a decrease in total gas production as yeast activity was compromised. The extreme freezing conditions of −20 °C and air speed of 0 m/s and −40 °C and air speed of 6 m/s had the poorest dough and steamed bread quality. Samples frozen at −30 °C had better form ratio of steamed bread than those frozen at −20 °C and −40 °C, while those frozen at −40 °C had the lowest specific volume. A moderate air speed of 3 m/s resulted in higher volume of total gas production and dough height, as well as better steamed bread texture. Keywords Frozen dough . Steamed bread . Protein content . Freezing rate . Freezing temperature . Freezing air speed Introduction While bread is commonly associated with oven and baking, steamed bread (also known as mantou or bao) is a staple food for many Asians. The main difference steamed bread has from baked bread would be the lack of a browned crust as steaming is a much gentler heat process compared to baking. Also, steamed bread has a moister and softer crumb. Besides processing, another major contributor to the difference between baked and steamed bread is that typical steamed bread recipes use low-protein flours (7.5–11 %) according to cultural and geographic diversity in China as well as the strength of different wheat cultivars (Ananingsih et al. 2013; Hou and Popper 2006; Kondakci and Zhou 2015; Zhu et al. 2001; Zhu 2014), while baked bread uses high-protein flours (12–14 %). Instead of distributing fresh bread, which declines in quality over distance and time, a central production of frozen dough allows for baking to be done at the point of sale such that bread can be sold and consumed fresh. Although steamed bread originated from northern China, it is currently a popular food in many Asian countries and becoming increasingly popular in the Western world as well. Consequently, frozen dough technology has become increasingly relevant for steamed bread production. With respects to steamed bread, a number of studies examined the effects of protein content on steamed bread quality, which was generally scored based on a system developed by Huang et al. (1996) that includes parameters such as specific volume, colour and eating quality. Lin et al. (1990) reported that a high-protein flour has more gluten to retain gas in the dough with regard to baked bread. They further recommended
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