Degree Of Starch Retrogradation Research Articles

Effect of lipase addition on inhibition of starch retrogradation in rice

We investigated whether the production of the free fatty acids (FFAs) by the addition of lipase during rice cooking inhibits starch retrogradation, and to examine whether proteins are involved in this process. Rice milled with milling ratios of 90%, 80%, 70%, and 60% and alkaline-soaked raw rice (AS) were prepared to obtain samples with different protein content. The protein content decreased from 8.24% to 5.83% as the milling ratio decreased from 90% to 60%, and AS contains 4.58% of protein. The prepared rice was cooked with and without lipase, and then treated with two freeze-thaw cycles to accelerate starch retrogradation. The addition of lipase increased the FFAs content and the peroxide value form 1.65 meq/kg to 4.75 meq/kg and decreased the free thiol (SH) content in cooked rice. The degree of swelling was reduced by 0.14 during cooking with the addition of lipase in cooked rice with a milling ratio of 90%. The degree of starch retrogradation (Dr) tended to increase as the milling ratios decreased from 90% to 60% and AS showed Dr similar to milling ratio of 60%. The degree of amylose-lipid complexes formation, which is involved in the inhibition of starch retrogradation, did not change with or without lipase, suggesting that the inhibitory effect of lipase became smaller as protein decreased. These results suggest that the FFAs produced by lipase converted the free SH of the protein into disulfide bonds, which altered the swelling characteristics of the starch and eventually inhibited the starch retrogradation.

Effects of cottonseed flour and enzyme addition on the wheat flour dough characteristics and snack cracker quality

In order to increase the protein content of snack cracker, different levels of cottonseed flour (CSF: 0, 10, 20, 30 g/100 g) and enzyme (Crackerase: 0, 0.02, 0.05 g/100 g) were added to cracker formula. The analysis of solvent retention capacity (SRC) found the lactic acid-SRC value of flours decreased, while water, sucrose, Na2CO3-SRC values increased with the increasing level of CSF. Alveograph results indicated CSF addition increased the tenacity and decreased the extensibility of dough. Enzyme addition decreased the tenacity and extensibility of dough. Mixolab analysis found that CSF addition increased the development time and mixing stability of dough, but resulted in lower peak viscosity and retrogradation degree of starch. At the same time, all the Mixolab parameters decreased after enzyme addition. Baking performance results indicated that CSF addition decreased the cracker breaking force and stack height, while enzyme addition increased the cracker stack height and decreased its breaking force. Sensory evaluation showed that high acceptability crackers could be produced at 20, 30 g/100 g CSF and 0.05 g/100 g enzyme addition levels. The results obtained in present study can give scientific and useful knowledge for food industry to produce nutritional crackers with high protein content.

Retrogradation-induced physicochemical changes in pre-cooked rice noodles stored at different temperatures: a viewpoint from water dynamics and structure.

There has been significant interest in pre-cooked noodles that have a long shelf life and are convenient to cook. However, the thermal processes during preparation, and their high moisture content, can lead to significant quality deterioration during storage. Nevertheless, a comprehensive evaluation of these quality losses has not yet been conducted. The effects of different storage temperatures (25, 4, and -20 °C) on the retrogradation-related physicochemical changes in pre-cooked rice noodles were elucidated mainly from the water dynamics and structural viewpoints. Thermal analysis demonstrated that amylopectin recrystallization took place in the noodles stored at refrigerated temperature, followed by room temperature. The refrigerated storage accelerated the starch retrogradation that caused the water molecules to become entrapped within the crystalline structure by lowering the water hydration properties and weighted T2 relaxation times of the pre-cooked noodles. These water mobility patterns were correlated with the textural changes in the noodles (greater hardness and Rmax /extensibility). Furthermore, the higher structural density and thickness derived from starch retrogradation were observed in the tomographic and microscopic images of the refrigerated noodles. The principal component analysis demonstrated that various physicochemical changes of the pre-cooked noodles during storage showed high correlations with the degree of starch retrogradation (r > 0.83). The physicochemical features of the precooked noodles stored under refrigerated conditions were involved in the molecular dynamics of water, showing a notable water mobility reduction derived from the starch retrogradation, which contributed to their thermal, tomographical, and textural changes. © 2023 Society of Chemical Industry.

Study of starch aging characteristics based on Terahertz technology.

Traditional methods for the determination of starch aging indicators often have a series of shortcomings such as time‐consuming, high cost, large human error, damage to samples, environmental pollution, and high requirements for inspectors. Therefore, it is meaningful to find or establish a dynamic fingerprint identification pattern that can detect the aging degree of starch during the process of processing or storage quickly and accurately. It not only provides guidance for starch food processing but also saves a lot of human, material resources, and time. Terahertz technology is an emerging molecular spectroscopy technology in the 21st century. It is with low energy and basically harmless to the human body. It can also realize nondestructive testing of samples. In the experiment, the samples were prepared by the tableting method and the samples containing 20% of 50 mg samples were prepared with polyethylene as the diluent. The thickness of the samples was 1 mm and the diameter was 13 mm. The terahertz time‐domain spectrometer was used to obtain the spectral information of aging starch at different aging times. After the pretreatment of the spectrum by vector normalization, first derivative, and multiple scattering correction, the prediction models of aging days, crystallinity, and resilience of aging starch were established, respectively. The determination coefficient (R 2) of the established models is all greater than 95%, indicating that the established models are highly reliable and can be used to predict the aging days, crystallinity, and retrogradation degree of starch. And the R 2 of the prediction model based on the refractive index spectrum is greater than that of the absorption coefficient spectrum. The experimental method obtains the dynamic fingerprint identification map of starch in the aging process, realizes the real‐time monitoring and detection of the starch aging process, and provides an effective means for the production and processing of starch‐related industries.

Model of Retrogradation of Extruded Potato Starch

AbstractStarch pastes represent unstable systems which tend to retrograde during storage. Starch recrystallisation increases gel hardness and releases entrapped water. This causes undesirable changes in the stability and texture of the whole product. This study aims to analyze the degree and rate of retrogradation. In addition, an attempt is undertaken to fit a retrogradation model for pastes prepared from starches with various granule sizes and subjected to a single or double extrusion process. Pastes prepared from double‐extruded starch are characterized by a lower degree of degradation compared to those made of non‐extruded and single‐extruded starches, and this decrease in degradation extent depends on extrusion process temperature. The degree of starch retrogradation in pastes increases along with greater diameters of starch granules. This is associated with granule size not only because of contents of amylose and amylopectin fractions in the granules but also because of the difference between their mean volumetric diameters.

Physicochemical properties of starches obtained from Polish potato cultivars

AbstractSelected physicochemical, thermal, and rheological properties of starches isolated from new Polish potato varieties were determined. The starches contained 25.7–30.0 g/100 g d.m. of amylose and 59.5–90.2 mg/100 g d.m. of phosphorus. Gelatinization temperatures were 62.6–64.0, 68.9–69.9, and 73.6–77.0°C for TO, TP, and TE, respectively, whilst enthalpy of gelatinization amounted to 11.1–15.3 J/g. The retrogradation degree of starch was from 52.90 to 78.53%. Pasting curves showed significant differences between the starches. Peak viscosity and final viscosity ranges were 2035–4458 and 1931–2985 mPa · s, respectively. Starch pastes exhibited non‐Newtonian, shear thinning, and thixotropic behavior. After cooling they demonstrated diversified viscoelastic properties, however, all of them were classified as weak gels. Significant linear correlations among selected rheological parameters and amylose and phosphorus content were found. Results of principal component analysis demonstrated an ability to differentiate the starches isolated from different potato varieties.

Starch Retrogradation and Texture of Cooked Milled Rice During Storage

ABSTRACT:The effect of storing cooked Bengal and Cypress milled rice at ‐13, 3, 20, and 36 °C on texture and degree of starch retrogradation was investigated. Cooked rice firmness increased, while stickiness decreased, during storage at ‐13 and 3 °C. Starch retrogradation, measured with a differential scanning calorimeter, was observed for both cultivars during storage at ‐13 and 3 °C, but not at 36 °C. At 20 °C, retrogradation occurred in Cypress, but not in Bengal. Starch retrogradation showed positive linear trends with firmness for both cultivars at all storage temperatures (R2= 0.80) and with stickiness for Bengal stored at ‐13 and 3 °C and for Cypress stored at 3 and 20 °C (R2 = 0.88).

Physicochemical Changes in Potato Granules During Storage

ABSTRACTPhysicochemical properties of freeze‐thaw (F‐T) and add‐back (A‐B) potato granules, such as swelling power (SP), water‐holding capacity (WHC), degree of starch retrogradation, moisture change, and rate of rehydration were monitored over about 100 wk of storage. SP of both types of granules decreased to minima after 40 wk then increased on further storage, while WHC showed an opposite trend, reaching maxima after 52 wk. Degree of starch retrogradation in the granules increased to maxima after 40 wk then declined. Moisture content of the granules also increased slightly during the first 33 wk then decreased on further storage. These changes caused the reduction in the rehydration rate of the granules from 8.3 × 10−2 see−1 to 5.5 × 10−2 set−1 (F‐T) and 5.2 × 10−2 sec−1 (A‐B) after 36 wk of storage, after which the rate again increased. Addition of Ca++ to the granules during precooking and cooling steps of the process appeared to cause similar changes.