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Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Starch, the principal carbohydrate in most diets, consists only of a water insoluble polymer of glucose joined by α-glucosidic bonds and is designated α-glucosan or α-glucan (7, 9). In other words, digestible starch is made up of long chains of glucose and comprises two polymers of glucose: amylose and amylopectin (7–9). Most cereal starches contain about 15 to 30% amylose and 70 to 85% amylopectin by weight (9). Some starches, from maize, rice, and sorghum to barley, contain largely amylopectin and are known as ‘waxy’ (7). Starch occurs in the form of granules deposited in plant organs. It is relatively dense, insoluble in cold water, and ranges from 1 to 100 µm in size depending on the plant species (7, 9). Starch furnishes energy to the body after digestion into glucose. In the digestive tract, insoluble starch is broken down into soluble glucose by different enzymes (amylases, dextrinase, glucoamylase, maltase, etc.) present in the mouth saliva, small intestine and pancreas secretion. To facilitate this digestion, starch must be cooked before eating. Recent studies suggest that slowly digested starch and enzyme resistant starch have significant implications for human health (7, 9). Starch plays a major part in supplying the metabolic energy that enables the body to perform different functions. It is the basic source of energy for the majority of the world’s population.
Components of Nutrition
Published in Christopher Cumo, Ancestral Diets and Nutrition, 2020
Due to their structure, not all starches affect the body the same. Being large, straight, and helical, amylose slows digestive enzymes from breaking it apart and is classified as resistant starch. The more amylose food has, the harder it is to digest. Although this characteristic might seem undesirable, foods that resist digestion do not inundate the bloodstream with glucose and so do not cause the pancreas to overproduce insulin. The body needs insulin to metabolize glucose, but too much produced too quickly and too often creates a condition known as insulin insensitivity, whereby cells lose their ability to respond to the hormone. This problem contributes to chronic diseases, notably type 2 diabetes, a malady linked to heart disease, stroke, and kidney disease. In 2017, the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, estimated that 100 million Americans have this kind of diabetes or are on its threshold.34 In contrast to amylose, the starch amylopectin, although larger, arrays its glucose molecules in branches that digestive enzymes readily dismantle. The more amylopectin in food, the more rapid is digestion, causing the above cascade of perils.
Starch-Based Nanocarriers of Nutraceuticals: Synthesis and Applications
Published in Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani, Nutraceuticals and Dietary Supplements, 2020
Alberto A. Escobar-Puentes, Adriana García-Gurrola, Fernando Martínez-Bustos
Starch is the main source of energy produced by photosynthesis in plants. It is found in nature as granular structures with dimensions ranging from 1 to 100 µm and with different morphologies. It is mainly composed of linear amylose and branched amylopectin molecules, polymers integrated into anhydrous glucose units (Kim et al., 2015). In the common native starch, amylose percentages vary between 72% and 82%, and amylopectin ranges between 18 and 28%. However, there are mutant starches such as high amylose (up to 70% and more for amilomaize) and low amylose (1% for waxy corn) contents (Bras and Dufresne, 2010). Amylose consists of linear molecules linked mainly by α-(1–4)-D-glycosidic bonds; however, it has now been established that some molecules are slightly branched by α-(1–6) bonds; amylopectin consists of branched chains formed by α-(1–6) bonds and with an average molar mass (Daltons) of up to hundreds of millions (Gul et al., 2016). The upgrowth of the microgranules starts in the hilum such as an onion-like structure with growth rings composed of crystalline and amorphous lamellae densely packed with a certain number of blocklets, with diameters of 20–500 nm (Kim et al., 2015). Concisely, considering a multiscale structure, there are the starch granules (1–100 µm) formed of growth rings (120–500 nm) composed of blocks (20–50 nm) made of amorphous and crystalline lamellae (9 nm) that contain amylopectin and amylose chains (0.1–1 nm) (Bras and Dufresne, 2010).
Cassava toxicity, detoxification and its food applications: a review
Published in Toxin Reviews, 2021
Anil Panghal, Claudia Munezero, Paras Sharma, Navnidhi Chhikara
In cassava, majority of the starch is stored within amyloplasts in the thickened root. The starch content in roots varies from 73.7% to 84.9% on dry weight basis (Asaoka et al.1991). Amylose varies from 13.6 to 23.8% and amylopectin is about 83%. The content of soluble amylose (which is thought to be responsible for cohesiveness in cooked starch) of cassava was found in range from 10 to 40% of total amylose. Water absorption capacity and swelling power of starch are essential parameter for its viscosity and textural attributes in finished product. Cassava starch has good potential as food industry base product due to its high viscosity, low tendency for retrogradation, low gelatinization temperature, and also the absence of the undesirable flavors found in many cereal starches (Demiate and Kotovicz 2011). The starch obtained from fresh roots is having more swelling power than the one obtained from dried roots, therefore have better textural and viscosity attributes of finished products (Zhu 2015). Moreno and Gourdji (2015) reported that high rainfall leading to humid conditions results in sprouting causing the translocation of photoassimilates from the roots to the top and thus declining both dry matter and starch content of the roots.
Resistant starch, microbiome, and precision modulation
Published in Gut Microbes, 2021
Peter A. Dobranowski, Alain Stintzi
Starch is synthesized in the amyloplast and chloroplast organelles of plants, forming mixtures of amylose and amylopectin. These molecules both consist of chains of glucose subunits linked by α-1,4- and α-1,6-glycosidic bonds, but differ in their chain length (i.e. degree of polymerization; DP) and branching (α-1,6 bonds). Amylose possesses a DP below 6,300 glucose subunits, almost entirely (>99.3%) bonded by α-1,4-glycosidic linkages.16 Conversely, amylopectin forms much larger molecules (DP up to 26,500) with dense networks of short chains (mean DP 15–18) branching from longer chains (mean DP 48 to 60).16 The intra- and intermolecular interactions of amylose and amylopectin impart starch granules with a complex hierarchical structure (Figure 1).
Amelioration of ethanol induced apoptotic DNA damage and ulcerative injuries in the mice gastric tissues by starch oral administration
Published in Toxicology Mechanisms and Methods, 2018
Sherin Ramadan Hamad, Hanan Ramadan Hamad Mohamed
Recently, there is a growing awareness that some of the compounds that naturally occur in plants have promising effects in the gastric ulcer treatment (Coşkun et al. 2004; Al-Bayaty et al. 2011; Rtibi et al. 2015; Mard et al. 2016). Starch (amylum) is a white, tasteless and odorless polysaccharide consisting of many glucose units joined by glycosidic bonds and produced by most green plants as energy store. This carbohydrate polymer consists of two molecule types including the linear and helical amylose and the branched amylopectin and represents the most common carbohydrate in human diets and present in large amounts in staple foods such as potatoes, wheat, maize (corn), rice and cassavais (Brown and Poon 2005). Starch has been shown to be a potent antioxidant by significant decreases in plasma thiobarbituric acid (TBA) reactive substances and significant increases in the activities of liver superoxide dismutase (SOD) and catalase (CAT) and the concentrations of serum and liver alpha-tocopherol in rats fed diet rich with starch (Hirao and Igarashi 2003).