Ultrasound‐Assisted Extraction of Lychee ( Litchi chinensis Sonn.) Seed Starch: Physicochemical and Functional Properties

Effects of plasma-activated water combined with ultrasonic treatment of corn starch on structural, thermal, physicochemical, functional, and pasting properties

In this study, corn starch was used as the raw material, and modified starch was prepared using a method combining plasma-activated water and ultrasound treatment (PUL). This method was compared with treatments using plasma-activated water (PAW) and ultrasound (UL) alone. The structure, thermal, physicochemical, pasting, and functional properties of the native and treated starches were evaluated. The results indicated that PAW and UL treatments did not alter the shape of the starch granules but caused some surface damage. The PUL treatment increased the starch gelatinization temperature and enthalpy (from 11.22 J/g to 13.13 J/g), as well as its relative crystallinity (increased by 0.51 %), gel hardness (increased by 16.19 %) compared to untreated starch, without inducing a crystalline transition. The PUL treatment resulted in a whitening of the samples. The dual treatment enhanced the thermal stability of the starch paste, which can be attributed to the synergistic effect between PAW and ultrasound (PAW can modify the starch structure at a molecular level, while ultrasound can further disrupt the granule weak crystalline structures, leading to improved thermal properties). Furthermore, FTIR results suggested significant changes in the functional groups related to the water-binding capacity of starch, and the order of the double-helical structure was disrupted. The findings of this study suggest that PUL treatment is a promising new green modification technique for improving the starch structure and enhancing starch properties. However, further research is needed to tailor the approach based on the specific properties of the raw material.

Extraction, modification, and characterization of native litchi seed (Litchi chinesis Sonn.) starch

BACKGROUND

Litchi seeds, because of their high starch content, have the potential to serve as a valuable non-conventional source of starch with various applications. This study aimed to optimize the extraction of native litchi seed and its modification using citric acid. Response surface methodology was used to determine the optimal combination of the independent variables extraction temperature (30-60 °C), and extraction time (4-20 h), to obtain the maximum starch yield (%). Starch was then modified chemically with citric acid concentrations of 20% and 40% to investigate its effect on physicochemical, morphological, and functional properties.

RESULTS

The second-order polynomial model effectively described the experimental data, demonstrating a satisfactory fit for the observed results. The optimized condition with the highest starch recovery (212.4 g kg-1 ) was found to have an extraction temperature of 30 °C and an extraction time of 11 h. It was observed that an increase in concentration of citric acid resulted in a decrease in amylose content, swelling power, and solubility, and the water absorption capacity of modified starch increased. The scanning electron microscopy (SEM) micrographs showed that citric acid modification resulted in surface irregularities, whereas the shape and size of granules remained unaffected. Not much difference was observed in the X-ray diffraction (XRD) pattern of modified starch except for the decrease in the intensities of peaks. An effect on the thermal properties of modified starch was also observed.

CONCLUSION

The results of the study reveal that extraction temperature and extraction time are critical factors, exerting a significant effect on the extraction yield of starch. Furthermore, modified starches with improved functional properties can serve as novel and versatile sources of starch in various food and non-food sectors. © 2023 Society of Chemical Industry.

Insights into the structural characteristics and in vitro starch digestibility on parboiled rice as affected by ultrasound treatment in soaking process

This study investigated ultrasound treatment as a protective parboiling technology for producing low GI rice. Indica and Japonica rice with different amylose contents were subjected to different ultrasound times (15 min, 30 min, and 60 min) and amplitudes (30, 60, and 100%) under soaking conditions for parboiling applications. Starch granules merged and lost their shape when ultrasound treatment time and amplitudes were increased up to 15 min and 30%, respectively. It increased the crystallinity, gelatinization temperatures and decreased pasting viscosity, promoting more resistant starch. The predicted glycemic index (GI) was reduced from 62.9 and 57.6 to 51.3 and 47.1 for Japonica and Indica, respectively. These results suggested that ultrasound soaking is a promising physical method to produce parboiled rice with a lower GI by promoting the formation of amylose chains and decreasing enzyme penetration efficiency.

Loquat seed starch - Emerging source of non-conventional starch: Structure, properties, and novel applications

Recently, non-conventional sources of starch have attracted attention due to their potential to provide cost-effective alternatives to traditional starch. Among non-conventional starches, loquat (Eriobotrya japonica) seed starch is an emerging source of starch consisting of the amount of starch (nearly 20 %). Due to its unique structure, functional properties, and novel applications, it could be utilized as a potential ingredient. Interestingly, this starch has similar properties as commercial starches including high amylose content, small granule size, and high viscosity and heat stability, making it an attractive option for various food applications. Therefore, this review mainly covers the fundamental understanding of the valorization of loquat seeds by extracting the starch using different isolation methods, with preferable structural, morphological, and functional properties. Different isolation and modification methods (wet milling, acid, neutral and alkaline) are effectively used to obtain higher amounts of starch are revealed. Moreover, insight into various analytical techniques including scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction used to characterize the molecular structure of the starch are discussed. In addition, the effect of shear rate and temperature on rheological attributes with solubility index, swelling power, and color is revealed. Besides, this starch contains bioactive compounds that have shown a positive impact on the enhancement of the shelf-life of the fruits. Overall, loquat seed starches have the potential to provide sustainable and cost-effective alternatives to traditional starch sources and can lead to novel applications in the food industry. Further research is needed to optimize processing techniques and develop value-added products that can be produced at a large scale. However, there is relatively limited published scientific evidence on the structural and morphological characteristics of loquat seed starch. Thus, in this review, we focused on different isolation techniques of loquat seed starch, its structural and functional characteristics, along with potential applications.

Ultrasound-Assisted Extraction of Mango (Mangifera indica) Kernel Starch: Chemical, Techno-Functional, and Pasting Properties

(1) Background: Starch is the main component of mango (Mangifera indica) kernel, making it an alternative to obtain an ingredient from a non-conventional source with potential application in food and other industrial applications; however, reports on the use of new extraction techniques for this material are scarce. The main objective of this research was to evaluate the effect of ultrasound-assisted extraction (UAE) on the yield, chemical, techno-functional, rheological, and pasting properties of starch isolated from a non-conventional source such as a mango kernel. (2) Methods: Different power sonication conditions (120, 300, and 480 W) and sonication time (10, 20, and 30 min) were evaluated along with a control treatment (extracted by the wet milling method). (3) Results: Ultrasound-assisted extraction increases starch yield, with the highest values (54%) at 480 W and 20 min. A significant increase in the amylose content, water-holding capacity, oil-holding capacity, solubility, and swelling power of ultrasonically extracted starches was observed. Similarly, mango kernel starch (MKS) exhibited interesting antioxidant properties. The sol-gel transition temperature and pasting parameters, such as the breakdown viscosity (BD) and the setback viscosity (SB), decreased with ultrasound application; (4) Conclusion: indicating that ultrasound caused changes in physical, chemical, techno-functional, rheological, and pasting properties, depending on the power and time of sonication, so it can be used as an alternative starch extraction and modification technique, for example, for potential application in thermally processed food products such as baked goods, canned foods, and frozen foods.

Effect of autoclave-cooling cycles combined pullulanase on the physicochemical and structural properties of resistant starch from black Tartary buckwheat

A starch-rich portion is produced as a by-product of black Tartary buckwheat processing. The effect of enzymatic combined with autoclaving-cooling cycles (one, two, or three times) on the physicochemical and structural properties of black Tartary buckwheat type 3 resistant starch (BRS) was evaluated. The autoclaving-cooling cycles enhanced solubility and reduced swelling, with the BRS content increasing from 14.12% to 25.18%. The high crystallinity of the BRS reflected a high molecular order. However, increasing the number of autoclaving-cooling cycles did not result in higher BRS content. The highest BRS yield in the autoclaved starch samples was 25.18% after double-autoclaving-cooling cycles. Furthermore, the autoclaving-cooling cycles altered the crystalline structure of black Tartary buckwheat, and the subsequent crystallinity changed from 36.33% to 42.05% to 38.27%. Fourier-transform infrared spectroscopy shows that the number of cycles results in more efficient double-helical packing within the crystalline lamella. Principal component analysis showed that the autoclaving-cooling cycle treatment leads to significant changes in the molecular structure of resistant starch (RS). These results indicated that autoclaving-cooling cycles might be a feasible way for producing RS from black Tartary buckwheat starch with better structural stability to expand their application range.