Effect of roasted pea flour/starch and encapsulated pea starch incorporation on the in vitro starch digestibility of pea breads
Introduction
Bread is a staple food which is consumed all over the world. A standard recipe of wheat-based white bread is usually wheat flour (100%), salt (1%), sugar (5%), yeast (3%) and a prescribed amount of water based on flour weight according to the AACC Approved Method 10-09.01 (AACC International, 1999). Wheat flour is very low in total dietary fibre (2.7% dry basis) and resistant starch (RS) (≤1% dry matter) (Goñi, García-Diz, Mañas, & Saura-Calixto, 1996), which makes wheat bread a high glycemic index (GI > 70) food.
Legumes are rich in protein, starch, and fibre, and a wide range of bioactive constituents (carotenoids, flavonoids, etc.) that are beneficial to human health when consumed in sufficient quantities (Mathers, 2002). Legumes were identified as low GI foods (GI < 55) more than 20 years ago (Jenkins et al., 1980, Rizkalla et al., 2002). They allow for an increased stability in insulin response due to a decrease in blood glucose fluctuation corresponding to the slower glucose release (Rizkalla et al., 2002). These properties can help in the prevention of obesity and high blood cholesterol, as well as diabetes (Kushi, Meyer, & Jacobs, 1999). The replacement of wheat flour completely by yellow pea (Pisum sativum) flour for bread making would largely promote pea utilization, and also produce a healthy and gluten-free alternative which is in high demand by increasingly diagnosed celiac disease patients, as well as those with wheat allergies (Sciarini, Ribotta, León, & Pérez, 2010) and gluten sensitivity.
Although slowly digestible in its native form, up to 94% of isolated pea starch will still be rapidly digestible after it is gelatinized (Chung, Liu, & Hoover, 2009). Thus, the challenge is how to retain or enhance the amount of slowly digestible starch (SDS) and resistant starch (RS) in the finished pea products after processing. Roasting is one of the most important technological operations in processing grain legumes. It modifies and significantly enhances flavor (Ma, Boye, Azarnia, & Simpson, 2016), texture (Kaur, Singh, & Sodhi, 2005), and appearance (Koksel et al., 1999, Özdemir and Devres, 2000) of the product. Felsman, Harvey, Linnerud, and Smith (1976) reported that enzymatic glucose release values from corn samples roasted at 93, 104 and 116 °C for 1–5 h were similar to those obtained from raw corn. However, few starch digestibility data of roasted pea have been reported. Furthermore, Venkatachalam, Kushnick, Zhang, and Hamaker (2009) reported that starch-entrapped calcium alginate microbeads provide a useful tool to control the glucose release from the beads. If roasting and encapsulation are synergistically applied to pea flour/starch, a new food ingredient with a better flavor and enhanced SDS and RS fractions could be expected, and these physically modified starch products would be favored by consumers rather than their chemically modified counterpart. However, to our knowledge, there is a dearth of information on starch digestibility of roasted pea flour/starch, and no published reports on incorporating roasted flour/starch and/or encapsulated legume starch in foods, especially in bread making.
The overall objective of this study was to research and develop new pea ingredients with enhanced SDS and RS content by roasting and encapsulation, and then to apply the resulting novel ingredients to make gluten-free pea bread. Characterization of the physicochemical and nutritional properties of these modified pea ingredients and breads using various analytical techniques was another objective of this project, to better understand the relationship between structure and functionality.
Section snippets
Materials
Pea seeds (cultivar Agassiz) from the 2015 growing season were provided by the Seed Increase Unit, Agriculture and Agri-Food Canada (Indian Head, Saskatchewan, Canada). The whole pea seeds were first cracked with an IKA mill (M10), and then milled to flour using an Udy cyclone mill (Model 3010-030; Udy Corp., Fort Collins, CO 80524, USA) and passed through a 500 µm sieve. The moisture content of the flour was 9.0% (db) measured by air-oven method (130 °C, 2 h). Two pea starches, NPS (11.1%
Enhancement of SDS and RS fractions by roasting
Roasting of pea flour and starch was attempted to enhance the SDS and RS fractions compared to their native counterparts. Table 1 shows total starch, apparent amylose content and starch nutritional fractions (RDS, SDS and RS) (dry basis) of native, boiled, or roasted pea flour/starch. Native Agassiz pea flour had 48.6% total starch, including 10.6% apparent amylose content. Neither oven roasting (160 °C, 30 min) nor microwave roasting (1.1 kW, 6 min) affected the total starch and apparent amylose
Conclusion
A batter-based formula and processing procedure were used to produce gluten-free breads using pea flour, starch, roasted flour/starch and starch-entrapped microbeads. The pea breads had a comparable loaf appearance (color, shape and volume), crumb structure and texture, and palatability to a wheat-based white bread control, but with enhanced SDS and RS content. Roasted pea flour/starch had a low in vitro starch digestibility profile similar to their native counterparts. However, when applied in
Acknowledgements
The authors thank Dr. D.J. Bing for providing Agassiz pea seeds, and Miss Esther Matus for conducting physicochemical analyses and in vitro starch digestibility. This study was supported by Agriculture and Agri-Food Canada through an Agri-Innovation Project Grant (Pulse Cluster AIP CL-03).
Conflict of interest
The authors declare that they have no conflict of interest.
References (19)
Approved methods of analysis
(1999)Approved methods of analysis
(2001)- et al.
Impact of annealing and heat-moisture treatment on rapidly digestible, slowly digestible and resistant starch levels in native and gelatinized corn, pea and lentil starches
Carbohydrate Polymers
(2009) - et al.
Colorimetric method for determination of sugars and related substances
Analytical Chemistry
(1956) - et al.
Classification and measurement of nutritionally important starch fractions
European Journal of Clinical Nutrition
(1992) - et al.
Effect of roasting temperature on corn grain characteristics
Journal of Animal Science
(1976) - et al.
Analysis of resistant starch: A method for foods and food products
Food Chemistry
(1996) - et al.
Effect of guar crispbread with cereal products and leguminous seeds on blood-glucose concentrations of diabetics
British Medical Journal
(1980) - et al.
Physicochemical, cooking, textural and roasting characteristics of chickpea (Cicer arietinum L.) cultivars
Journal of Food Engineering
(2005)
Cited by (41)
Effect of hydrocolloids on starch digestion: A review
2024, Food ChemistryPea protein and starch: Functional properties and applications in edible films
2024, Journal of Agriculture and Food ResearchEffect of modified starches on the quality of skins of glutinous rice dumplings
2023, International Journal of Biological Macromolecules