Effect of freezing and heating white bread on the glycemic response of healthy individuals

Document Type : Original Article


1 Basic Science Nursing Department, College of Nursing, University of Mosul, Mosul, Iraq

2 Clinical Science Nursing Department, College of Nursing, University of Mosul, Mosul, Iraq


Background: Freezing starchy food causes the starch structure to break down, resulting in resistant starch that behaves like fiber. This leads to a slower rise in blood sugar, which may reduce the risk of type 2 diabetes and weight gain.
Objectives: This study aimed to investigate the impact of reheated white bread and frozen versions on the glycemic responses of healthy individuals.
Methods: A randomized controlled trial was conducted on 32 healthy participants (14 males and 18 females) aged 18–50 years with a body mass index (BMI) of 18.5-29 kg/m² and fasting blood sugar levels of 75–100 mg/dl. The participants were given 100 grams of fresh white bread made from Turkish flour (Al-Haramain type), and their blood sugar levels were measured at 30, 60, 90, and 120 minutes. This process was repeated after feeding the participants with 100 grams of frozen bread for 3, 5, and 7 days to observe the effect of freezing and reheating white bread on blood sugar levels, as well as the impact of freezing duration.
Results: The glycemic response of the participants to frozen and reheated white bread was lower compared to fresh white bread at all time intervals. The maximum blood sugar level was reached after 30 minutes of consuming fresh bread, at 132 mg/dl. However, for reheated bread, it reached 120 mg/dl. The prolonged freezing time did not increase the amount of resistant starch, and similar results were observed for 3, 5, and 7 days of freezing in terms of decreasing blood sugar levels.
Conclusion: Frozen and reheated white bread leads to lower blood sugar levels compared to fresh white bread. This can be attributed to the formation of resistant starch during the freezing process.


Main Subjects

  1. Sajilata MG, Singhal RS, Kulkarni PR. Resistant starch-a review. Compr Rev Food Sci Nutr. 2006; 5 (1):1-17. doi:10.1111/j.1541-4337.2006.tb00076.x PMid:33412740
  2. Zaman SA, Sarbini SR. The potential of resistant starch as a prebiotic. Crit Rev Biotechnol. 2016;36(3):578-84.
  3. Topping DL, Fukushima M, Bird AR. Resistant starch as a prebiotic and synbiotic: state of the art. Proc Nutr Soc. 2003; 62 (1):171-6. doi:10.1079/PNS2002224 PMid:12749342
  4. Zello GA. Dietary Reference Intakes for the macronutrients and energy: considerations for physical activity. Appl Physiol Nutr Metabol. 2006;31(1):74-9. doi:10.1139/h05-022 PMid:16604146
  5. Hattner JA, Anderes S, Saavedra JM. Gut Insight: Probiotics and Prebiotics for Digestive Health and Well-Being by Jo Ann Hattner, MPH, RD, With Susan Anderes, 2009; Available at www.gutinsight.com. Infant Child Adolesc Nutr. 2009; 1(6):351. doi:10.1177/1941406409354462
  6. Fuentes-Zaragoza E, Riquelme-Navarrete MJ, Sánchez-Zapata E, Pérez-Álvarez JA. Resistant starch as functional ingredient: A review. Food Res Int. 2010;43(4):931-42. doi:10.1016/j.foodres.2010.02.004
  7. Nugent AP. Health properties of resistant starch. Nutr Bull. 2005;30(1):27-54. doi:10.1111/j.1467-3010.2005.00481.x
  8. Ananda D, Zuhairini Y, Sutadipura N. Resistant starch in cooled white rice reduce glycaemic index. Obes Res Cli Pract. 2013;(7):38. doi:10.1016/j.orcp.2013.08.095
  9. Lockyer S, Nugent AP. Health effects of resistant starch. Nutr bull. 2017;42(1):10-41. doi:10.1111/nbu.12244
  10. Bednar GE, Patil AR, Murray SM, Grieshop CM, Merchen NR, Fahey Jr GC. Starch and fiber fractions in selected food and feed ingredients affect their small intestinal digestibility and fermentability and their large bowel fermentability in vitro in a canine mode. J Nutr. 2001;131(2):276-86. doi:10.1093/jn/131.2.276 PMid:11160546
  11. Ashwar BA, Gani A, Shah A, Wani IA, Masoodi FA. Preparation, health benefits and applications of resistant starch-A review. Starch‐Stärke. 2016;68(3-4):287-301. doi:10.1002/star.201500064
  12. Raigond P, Ezekiel R, Raigond B. Resistant Starch in Food: A Review. J Sci Food Agric. 2014. doi:10.1002/jsfa.6966 PMid:25331334
  13. Burton P, Lightowler HJ. The impact of freezing and toasting on the glycaemic response of white bread. Eur J Cli Nutr. 2008; 62 (5): 594-9. doi:10.1038/sj.ejcn.1602746 PMid:17426743
  14. Cummings JH, Macfarlane GT, Englyst HN. Prebiotic digestion and fermentation. Am J Clin Nutr. 2001;73(2):415s-20s. doi:10.1093/ajcn/73.2.415s PMid:11157351
  15. Andoh A, Tsujikawa T, Fujiyama Y. Role of dietary fiber and short-chain fatty acids in the colon. Curr Pharm Des. 2003;9(4): 347-58. doi:10.2174/1381612033391973 PMid:12570825
  16. Grabitske HA, Slavin JL. Gastrointestinal effects of low-digestible carbohydrates. Crit Rev Food Sci Nutr. 2009;49(4):327-60. doi:10.1080/10408390802067126 PMid:19234944
  17. Johnston KL, Thomas EL, Bell JD, Frost GS, Robertson MD. Resistant starch improves insulin sensitivity in metabolic syndrome. Diabet Med. 2010;27(4):391-7. doi:10.1111/j.1464-5491.2010.02923.x PMid:20536509
  18. Bodinham CL, Smith L, Thomas EL, Bell JD, Swann JR, Costabile A, et al. Efficacy of increased resistant starch consumption in human type 2 diabetes. Endocr Connect. 2014;3(2):75-84. doi:10.1530/EC-14-0036 PMid:24671124 PMCid:PMC3987287
  19. Dhar A, Kumar D, Sharma A, Dewan D. Effect of hot and cooled carbohydrate diet on glycemic response in healthy individuals: a cross over study. Int J Res Med Sci. 2021;9:828-32. doi:10.18203/2320-6012.ijrms20210886
  20. Sonia S, Witjaksono F, Ridwan R. Effect of cooling of cooked white rice on resistant starch content and glycemic response. Asian Pac J Clin Nutr. 2015;24(4):620-5.