A low glycemic index starch binder for energy bars and features thereof

Abstract

The application discloses a low glycemic index starch adhesive for energy bars, and belongs to the technical field of deep processing of starch and food industry. The starch adhesive is prepared from corn starch through a pure physical annealing process, and meets the following characteristics: the content of RS3 type resistant starch is greater than or equal to 10%, the melting temperature of the RS3 type resistant starch is greater than or equal to 120 DEG C, the adhesive strength is greater than or equal to 5 N / cm2, the qualified rate of cold processing forming is greater than or equal to 95%, and the ingredient table only contains the starch. The low GI starch adhesive of the application can provide adhesive forming and a carbon source for energy bars, and meanwhile, the natural characteristics and clean label advantages of the starch are maintained, and the low GI starch adhesive is suitable for cold processing forming products such as energy bars, protein bars and cereal bars.

Description

Technical Field

[0001] This invention belongs to the field of starch deep processing and food industry technology, specifically relating to a starch adhesive product for energy bars that is produced by a pure physical annealing process, has a low glycemic index and excellent adhesion properties. Background Technology Energy bars are a core category in the global sports nutrition and convenient meal replacement market, with a market size exceeding tens of billions of US dollars. Starch binders are a key component in energy bar formulations, responsible for binding loose ingredients such as protein powder, nuts, cereal flakes, and dried fruit into a shaped form, and giving the product a suitable texture and taste. Traditional energy bars often use maltose syrup, glucose syrup, or invert sugar syrup as binders. While these syrups have high binding strength and good cold-processing properties, their GI values ​​are typically between 70 and 90, causing a rapid rise and fall in blood sugar after consumption, which contradicts the "continuous energy supply" positioning of energy bars. At the same time, the high sugar content of the formulation results in an excessively high calorie density, which is not conducive to weight management. To reduce the glycemic index (GI) and sugar content of energy bars, some products use soluble dietary fiber (such as fructooligosaccharides and inulin) instead of syrup as a binder. However, the binding strength of dietary fiber is much lower than that of syrup, making the energy bars prone to cracking and crumbling, and excessive addition of dietary fiber can lead to bloating and other discomfort. While chemically modified starch has good binding properties, the ingredient list must include "chemically modified starch," which does not conform to the trend of clean labeling. Currently, there is a lack of starch binder products on the market that can provide sufficient binding strength, can be molded under cold processing conditions, and simultaneously offer the advantages of low GI and clean labeling. The applicant's prior patent application disclosed a purely physical annealing modification technology that can generate high-melting-point RS3-type resistant starch in situ inside starch granules without adding any exogenous components through precise temperature and humidity control. This high-melting-point RS3-type resistant starch has high crystallinity and a melting temperature ≥120℃, forming an adhesive-active crystalline layer on the granule surface after annealing. This invention specifically applies this technology to the field of energy bar starch adhesives, defining for the first time a dedicated energy bar starch adhesive product with high RS3 content, excellent adhesive strength, and low GI value. Its quality is comprehensively defined through five quantitative indicators: RS3 content, RS3 melting temperature, adhesive strength, cold-processing molding pass rate, and ingredient list. Summary of the Invention Purpose of the invention This invention provides a starch adhesive product for energy bars that is produced by a purely physical annealing process, has excellent adhesion properties and a low glycemic index, and its quality is fully defined by five quantitative indicators. Technical solution This product uses corn starch as raw material, which is adjusted with water to a moisture content of 20%-35% and then annealed for 10-18 minutes in a constant temperature and humidity environment at 60-70℃ and 80%-95% relative humidity. During annealing, amylose molecules rearrange themselves in an orderly manner along the surface of residual microcrystals to form high-melting-point RS3 resistant starch. After annealing, a crystalline layer with adhesive activity is formed on the surface of the particles. After annealing, the product is rapidly cooled to below 25℃ in a fluidized bed within 90 seconds to lock the RS3 lattice structure. It is then dried at a low temperature not exceeding 50℃ to a moisture content of below 13%. The resulting starch adhesive product simultaneously meets the following requirements: RS3 resistant starch content ≥10%, RS3 resistant starch melting temperature ≥120℃, adhesive strength ≥5N / cm², cold processing molding qualification rate ≥95%, and the ingredient list contains only the stated starch. Core Mechanism The quality of the starch binder for energy bars is determined by three dimensions: adhesive performance, glycemic quality, and label cleanliness. In terms of adhesive properties, the RS3 crystalline layer formed on the surface of starch granules after annealing exhibits unique cold-adhesive activity. Natural starch requires gelatinization in hot water to produce adhesiveness—hot water causes the starch granules to swell, dissolves amylose, and forms a gel network after drying, providing adhesive strength. This is the traditional "thermal adhesive path." However, annealing is generally considered to increase the crystallinity and thermal stability of starch (i.e., making it less prone to gelatinization). Based on conventional understanding, those skilled in the art would reasonably expect that annealing reduces rather than enhances the cold-working adhesive properties of starch. The counterintuitive discovery of this invention is that the RS3 crystalline layer formed on the surface of the annealed particles possesses high surface energy. Under cold processing conditions (room temperature, pressure, trace moisture), it can form a stable adhesive bond with the surfaces of raw materials such as protein powder, nut pieces, and cereal flakes through hydrogen bonds and van der Waals forces. This is a "cold bonding path" different from traditional thermal bonding—it does not rely on the gelatinization and gelation of starch, but rather on the surface physicochemical properties of the RS3 crystalline layer. In Comparative Example 4, toughened starch (also a physical modification method, but treated at low temperature for a long time, resulting in insufficient formation of the RS3 crystalline layer) was used as a binder, and its adhesive strength was only about 2.8 N / cm², far lower than the 6.5 N / cm² of annealed starch. This demonstrates that the cold bonding activity of the RS3 crystalline layer is a unique contribution of the annealing treatment, rather than a common effect of all physical modification methods. Natural starch lacks adhesive properties under cold processing conditions (Comparative Example 2, adhesive strength approximately 1 N / cm²). Commercial resistant starch, due to its strong hydrophobicity and low surface energy, exhibits an adhesive strength of only approximately 2 N / cm² after physical blending (Comparative Example 3). Although chemically cross-linked starches possess high adhesive strength, their adhesion originates from covalent cross-linking rather than the surface energy of the physically crystalline layers. In terms of blood glucose quality, the slow digestion property of RS3-type resistant starch endows the starch binder with a low GI value. The high melting temperature (≥120°C) of RS3-type resistant starch ensures that the starch binder maintains structural integrity during possible subsequent processing of energy bars (such as coating and baking), and its adhesion function and low GI property are not affected. Detection Methods The content of RS3-type resistant starch is determined according to the standard method of AOAC 2002.02. The melting temperature of RS3-type resistant starch is determined by differential scanning calorimetry (heating rate: 10°C / min, nitrogen atmosphere, sample mass: 3-5mg, temperature range: 30-180°C, and the peak temperature of the endothermic peak is recorded). The adhesive strength is determined by the following method: mix the starch binder and protein powder at a mass ratio of 1:1, add distilled water accounting for 30% of the total mass of the starch binder and protein powder to prepare a dough, press the dough into a sheet with uniform thickness (2cm in width and 1cm in thickness) in a mold, and dry at room temperature until the moisture content is about 10%. A texture analyzer equipped with a three-point bending probe is used to measure the maximum breaking force (unit: N) of the sample, which is divided by the sample width (2cm) to obtain the adhesive strength (unit: N / cm²). The qualification rate of cold processing molding is determined by the following method: mix the starch binder and protein powder at a mass ratio of 1:1, add distilled water accounting for 30% of the total mass to prepare a dough, press and mold the dough in an energy bar mold, and dry at room temperature until the moisture content is about 10%. Drop the molded energy bar sample freely from a height of 50cm onto a stainless steel table for 3 times. A sample is qualified if the total length of edge fragmentation is ≤5mm and the percentage of the mass of fallen debris in the total mass of the sample is ≤3%. 10 energy bars are tested, and the percentage of the number of qualified samples in the total number of tested samples is the molding qualification rate. Beneficial Effects (1) A complete quality index system for special starch binders for energy bars is defined for the first time: the low GI property and processing stability are guaranteed by RS3 content and RS3 melting temperature, the molding without fragmentation of energy bars is guaranteed by adhesive strength, the reliability of the production process is guaranteed by the qualification rate of cold processing molding, and the clean label property is guaranteed by the ingredient list. (2) It is pure physical processing with zero addition, and the ingredient list only contains starch. (3) It is suitable for cold-processed molded products such as energy bars, protein bars, cereal bars and meal replacement bars. Specific Embodiments Example 1 Take corn starch, add water to condition the moisture content to about 28%, feed it into constant temperature and humidity equipment, and perform mild annealing at 65°C and 85% humidity for 14 minutes. After annealing, the mixture is quenched to below 25°C within 90 seconds by a fluidized bed with -5°C cold air, and dried at a low temperature of 45°C until the moisture content is about 12%, so as to obtain the starch binder for energy bars. The resulting product has an RS3 resistant starch content of 11.5%, an RS3 melting temperature of 125℃, an adhesive strength of 6.5 N / cm², and a 100% cold-processing molding pass rate (all 10 bars tested passed, total length of edge breakage was 0 mm, and the crumb rate was 1.2%). The ingredient list contains only corn starch. The product was mixed at a 25% mass ratio with protein powder, chopped nuts, rolled oats, and dried fruit, and then pressed into energy bars at room temperature. The energy bars were well-formed, did not break, did not crumble, and had a crispy texture. Comparative Example 1 (using malt syrup, high GI value) Replacing the annealed starch binder in Example 1 with maltose syrup, while keeping all other conditions unchanged, resulted in energy bars with an adhesive strength of approximately 8 N / cm² (≥5 N / cm²) and a 100% pass rate in cold forming. However, the GI value of maltose syrup is approximately 85, causing a rapid rise and fall in blood sugar after consumption, which contradicts the "continuous energy supply" positioning of energy bars. Furthermore, the product has a high total sugar content, which does not align with the trend towards clean labeling. This demonstrates that while maltose syrup has excellent adhesive properties, its excessively high GI value fails to meet the requirements for low-GI energy bars. Comparative Example 2 (using unmodified starch, resulting in insufficient adhesive strength) The annealed starch binder in Example 1 was replaced with untreated corn starch of the same variety, while all other conditions remained unchanged. After cold processing and pressing, the energy bars immediately cracked and crumbled, with an adhesive strength of only about 1 N / cm² (<5 N / cm²), and a molding pass rate of only 20% (8 out of 10 bars showed obvious cracking). This proves that unmodified starch does not have adhesive ability under cold processing conditions. Comparative Example 3 (physical blend of commercial resistant starch, insufficient adhesive strength) Untreated corn starch and commercial RS3 resistant starch were physically mixed at a mass ratio of 7:3, with other conditions remaining unchanged. The resulting mixed starch had an RS3 content of approximately 10.5%, but the energy bars were easily broken after cold processing and pressing, with an adhesive strength of only about 2 N / cm² (<5 N / cm²) and a molding pass rate of only 40%. This demonstrates that simple physical blending cannot impart sufficient adhesive strength to starch binders, and that the pure physical annealing route has irreplaceable advantages in adhesive performance. Comparative Example 4 (using toughened starch, insufficient adhesive strength) Toughened corn starch (treatment conditions: toughening treatment at 50℃, 25% moisture content for 24 hours, RS3 content approximately 5%) was used as the binder, with other conditions remaining unchanged. Toughening treatment is also a physical modification method, but the treatment temperature was lower and the time longer, resulting in insufficient formation of an RS3 crystalline layer on the starch granule surface. The resulting binder had an adhesive strength of only approximately 2.8 N / cm² (<5 N / cm²), and a molding pass rate of only 50%. This demonstrates that the cold adhesive activity of the RS3 crystalline layer is a unique contribution of annealing treatment, and not a common effect of all physical modification methods. Toughening treatment and other physical methods cannot replace the technical effect of annealing treatment in energy bar bonding applications. Industrial applications This product is suitable for the production of cold-formed products such as energy bars, protein bars, cereal bars, and meal replacement bars. The product's RS3 content, RS3 melting temperature, adhesive strength, cold-forming pass rate, and ingredient list must be included in the product's factory inspection standards. The ingredient list contains only the stated starch and meets clean label requirements. This product is particularly suitable for energy bar brands that prioritize low GI, clean labeling, and good forming quality.

Claims

1. A low glycemic index starch binder for energy bars, characterized in that, The starch binder is made from corn starch through a purely physical annealing process, and simultaneously meets the following characteristics: RS3 resistant starch content ≥10%, RS3 resistant starch melting temperature ≥120℃, adhesive strength ≥5N / cm², cold processing molding qualification rate ≥95%, and the ingredient list contains only the starch mentioned above.

2. The starch adhesive according to claim 1, characterized in that, The RS3 type resistant starch content is ≥11.5%, and the adhesive strength is ≥6.5 N / cm².

3. The application of the starch binder according to claim 1 or 2 in the preparation of energy bars, protein bars, cereal bars, and meal replacement bars.