Sweet Potato Peel Research Articles

Unveiling the structural characteristics and anti-inflammatory potential of a novel polysaccharide from sweet potato peels

Sweet potato tubers generate a significant amount of peel waste during starch production, leading to resource inefficiency and environmental pollution. This research focused on the isolation/purification of a novel polysaccharide from sweet potato peel, named as sweet potato polysaccharide (SPP-W). The SPP-W has a molecular weight of 5.764 kDa and consist of glucose monosaccharides. The backbone of SPP-W was composed of →4)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1→, and →3,4)-β-D-Glcp-(1→. The branched chain was α-D-Glcp-(1→ linked to the O-6 position of the sugar residue→4,6)-α-D-Glcp-(1→ and the O-3 position of the sugar residue→3,4)- β-D-Glcp-(1→ as confirmed by methylation and NMR analysis. SPP-W was found helpful in reducing the excessive NO, up-regulating IL-10, down-regulating the release of IL-6, IL-1β and TNF-α with LPS-induced RAW264.7 cell inflammation model. Furthermore, SPP-W effectively mitigates oxidative stress by reducing ROS levels, preventing nuclear damage, and preserving mitochondrial membrane potential in the context of inflammation. Immunoassays demonstrated that the clearance of endogenous ROS and the improvement of inflammatory conditions were attributable to the activation of the Nrf2 signaling pathway and inhibition of the NF-κB signaling pathway by SPP-W. Conclusively, SPP-W holds promise as a potential active ingredient for anti-inflammatory functional foods, offering unique and beneficial properties for further research and development.

Impact of cultivar types and thermal processing methods on sweet potato metabolome, a comparative analysis via a multiplex approach of NIR and GC–MS based metabolomics coupled with chemometrics

This study comprehensively analyzes the primary metabolites of sweet potato peels and pulps from four cultivars and assesses the impact of four different processing methods on pulp metabolome using a multiplex metabolomics approach of GC–MS and NIR. A total of 69 metabolites were identified. Beauregard cv. showed the highest sugar content (387.85 mg/g), whereas Sahrawy cv. was higher in alcohols (24.63 mg/g) and organic acids (2.98 mg/g). The chemometric analysis identified key markers that distinguished each cv. represented by its pulp, peel, and processed pulp. KEGG enrichment analysis pinpointed key metabolic pathways leading to the metabolic discrepancy of the specimens. Sugars were the most altered class by processing as manifested by a 5 to 11-fold increase, notably in the air-fried pulp. Air-frying also increased alcohol and organic acid contents. NIR analysis revealed that air-frying was the preferred method of processing, preserving the majority of pulp's metabolites, including β-carotene and phenolics.

Improving Structural, Physical, and Sensitive Properties of Sodium Alginate–Purple Sweet Potato Peel Extracts Indicator Films by Varying Drying Temperature

Sodium alginate (SA)–purple sweet potato peel extracts (PPE) from industrial waste indicator films were developed at different drying temperatures (25, 30, 35, 40, 45, 50, and 55 °C). The effects of drying temperatures on the film’s structural, physical, and sensitive properties were investigated. On the structural properties, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction indicated that compactness, intermolecular interactions, and crystallinity of indicator films were improved at a lower drying temperature. On the physical properties, with the drying temperature increasing, elongation at the break increased significantly (p < 0.05); ΔE and water-vapor permeability decreased significantly (p < 0.05); and thickness and tensile strength initially increased significantly (90.46 → 98.46, 62.99 → 95.73) and subsequently decreased significantly (98.46 → 71.93, 95.73 → 55.44) (p < 0.05), with the maximum values obtained at 30 °C. On sensitivity, the corresponding colors of the films became lighter as the drying temperature increased, and the films exhibited relatively excellent pH and NH3 sensitivity, with easily discernible color changes at lower temperatures. The results of this paper revealed that the overall film characteristics are improved at lower drying temperatures, which will provide valuable references for selecting the drying temperature for preparing indicator films as a guide for industrialized production.

Exploring the Potential of Anthocyanin-Based Edible Coatings in Confectionery-Temperature Stability, pH, and Biocapacity.

This study aims to develop purple-coloured polymeric coatings using natural anthocyanin and desoxyanthocianidins (3-DXA) colourants for application to chocolate almonds. The objective is to achieve a stable and uniform colour formulation throughout processing and storage, enhancing the appearance and durability of the almonds to appeal to health-conscious consumers and align with market demands. Plant materials like sweet potato pulp, sweet potato peel, radish peel, black carrot, and sorghum were employed to obtain the desired purple hue. Anthocyanidins and 3-DXA were extracted from the matrices using solvent extraction and ultrasound-assisted methods at different pH values. High-performance liquid chromatography with diode array detection (HPLC-DAD) and high-resolution tandem mass spectrometry (HRMS/MS) were used to identify the compounds in the extracts. The highest antioxidant capacities, as measured by the DPPH• and FRAP methods, were observed in purple sweet potato and dye factory extracts, respectively; meanwhile, sorghum extract inhibited both α-amylase and α-glucosidase, indicating its potential for managing postprandial hyperglycemia and type 2 diabetes. The degradation kinetics of coloured coatings in sugar syrup formulations with anthocyanins and 3-DXA revealed that locust bean gum offered the best colour stabilization for plant extracts, with sorghum extracts showing the highest and black carrot extracts the lowest colour variation when coated with Arabic gum. Sweet potato pulp extracts exhibited less colour variation in sugar pastes, both with and without blue spirulina dye, compared to factory dye, highlighting their potential as a more stable and suitable alternative for colouring purple almonds, particularly over a five-month storage period. This study supports sustainable practices in the confectionery industry while aligning with consumer preferences for healthier and environmentally friendly products.

Advances in valorization of sweet potato peels: A comprehensive review on the nutritional compositions, phytochemical profiles, nutraceutical properties, and potential industrial applications.

During food production, food processing, and supply chain, large amounts of food byproducts are generated and thrown away as waste, which to a great extent brings about adverse consequences on the environment and economic development. The sweet potato (Ipomoea batatas L.) is cultivated and consumed in many countries. Sweet potato peels (SPPs) are the main byproducts generated by the tuber processing. These residues contain abundant nutrition elements, bioactive compounds, and other high value-added substances; therefore, the reutilization of SPP holds significance in improving their overall added value. SPPs contain abundant phenolic compounds and carotenoids, which might contribute significantly to their nutraceutical properties, including antioxidant, antimicrobial, anticancer, prebiotic, anti-inflammatory, wound-healing, and lipid-lowering effects. It has been demonstrated that SPP could be promisingly revalorized into food industry, including: (1) applications in diverse food products; (2) applications in food packaging; and (3) applications in the recovery of pectin and cellulose nanocrystals. Furthermore, SPP could be used as promising feedstocks for the bioconversion of diverse value-added bioproducts through biological processing.

Exploring the biorefinery potential of sweet potato crop residues through torrefaction and pyrolysis: Processing of leaves, stems, and peel

The utilization of neglected agro-industrial waste is essential for mitigating environmental impacts. This study aims to characterize the products of using sweet potato peels, leaves and stems via pyrolysis and torrefaction techniques. Additionally, the study examined the impact of the torrefaction pre-treatment on pyrolysis products. Solid, liquid, and gaseous products were characterized. Results indicated that torrefaction pre-treatment increased biochar yield but diminished bio-oil and gas yields. Thermal treatments had minimal impact on the specific surface area of formed solids and biochars. Bio-oils showed a proclivity towards basicity with increasing temperature. Phenols predominated in the organic fraction of bio-oils, with torrefaction pre-treatment resulting in reduced alcohol and increased hydrocarbon concentration. Gas composition revealed elevated CO2 levels during torrefaction, while torrefaction pre-treatment amplified CH4 concentration. These findings suggest potential for extracting chemical inputs like phenolic resins and biocides from sweet potato waste bio-oils, though further treatments are required for effective solid adsorption.

Degradation of chemical oxygen demand, suspended solids and ammoniacal nitrogen from sewage by sweet potato peel coagulant under the influence of pH

Degradation of chemical oxygen demand, suspended solids and ammoniacal nitrogen from sewage by sweet potato peel coagulant under the influence of pH

Functionalization of wheat bread with prebiotic dietary insoluble fiber from orange-fleshed sweet potato peel and haricot bean flours

The development of functional foods is leading the way toward making diets more beneficial for human health. Prebiotics are among the simplest and safest ways to address some of this issue. However, the selection of simple food systems that better convey their functional properties remains an area that needs further investigation. Thus, this study aims to contribute to the aforementioned concern by developing functional and nutritionally balanced bread. Composite flour was formulated using wheat, orange flashed sweet potato peel (OFSPP), and haricot bean flours. Proximate and β-carotene content, functional, pasting, and physical properties of composite flours, and quality parameters of the developed bread were determined and analyzed by employing appropriate methods. The functionality of the composite flours has been increased in terms of both dietary fibers (2–8.4 g/100g) and β-carotene content (ND–731μg/100g). Similarly, the protein content of the formulated flour has increased from 11.25 to 17.4 g/100g. The consumer-based sensorial investigation further revealed that the produced bread's sensory acceptability is not markedly compromised by the addition of OFSPP and haricot bean flour up to 10% and 20%, respectively. Nevertheless, animal and human gut microbiome studies are still needed in the future to further reinforce the findings of this study.

Development of food packaging bioplastic from potato peel starch incorporated with rice husk silica using response surface methodology comprehending central composite design

Rice husk and sweet potato peel are agricultural waste with high potential and economic interest. The utilization of these materials in product development will provide substantial improvement toward waste reduction. Therefore, this study aimed to develop a food packaging bioplastic using potato peel and rice husk. The optimization of three parameters (ratio of silica, the volume of glycerol and volume poured) was set in Design Expert Software version 13 to find the best formulation. The software set eighteen formulations to measure advanced bioplastic thickness, density, and moisture content. The optimum formulation exhibits thickness, density and moisture content with the value of 1.87 mm, 0.196 g/mL and 31.224%, respectively. In response surface methodology, bioplastic formulation was optimized using central composite design (CCD). The statistical model displayed an excellent fit with standard deviation, R2 data. The R2 for thickness was 0.8946, while 0.9516 for density and 0.96 for moisture content. These values were close to 1, indicating the significant effect on the tested conditions to get the optimum formulation.

Simultaneous Saccharification and Fermentation (SSF) of Blended Organic Fertilizer from Yam and Sweet Potato Peels

This study shows the production of organic fertilizer by utilization of yam and sweet potatoes peels through Simultaneous Saccharification and Fermentation (SSF) Method. Samples are categorized into sun-dried, sundried and autoclaved, Heat-dried, heat-dried and autoclaved, the fermentation process is carried out using alpha amylase and saccharomyces cerevisiae. Investigation of mineral elements (N, Cd, P, Zn, Pb, As, K, Hg.), in the eight varieties of Organic Fertilizer produced shows concentration of Cadmium (Cd) ranges from 0.0015 mg/kg to 0.0033 mg/kg), Nitrogen (N) in Percentage ranges from 2.3450% to 3.8550%; Phosphorus (P) ranges from 2.345 mg/kg to 3.607 mg/kg; Zinc (Zn) ranges from 2.215 mg/kg to 6.335 mg/kg. Lead (Pb) ranges from 0.00 mg/kg to 0.0015 mg/kg, potassium (K) ranges from 3.952 mg/kg to 6.213 mg/kg; Mercury and Arsenic nil. The study shows that Sweet Potato Peel (SDSPP) contains high Cadmium and potassium compare to other organic fertilizer produced. Sundried and Autoclaved Yam Peel (SDAYP) contains high percentage of Nitrogen (N), Heat Dried and Autoclaved Sweet Potato Peel (HDASPP) contains low Nitrogen, Sundried and Autoclaved Sweet Potato Peel (SDASPP) contains low phosphorus, Sundried Yam Peel (SDYP), Sundried and Autoclaved Yam Peels (SDAYP), Heat Dried Sweet Potato Peel HDSPP and Heat Dried Sweet Potato Peel (HDSPP) has zero trace of Lead (Pb) making it free of food intoxication from heavy metals, SDYP contains high phosphorus. These indicate that the samples will make quality organic fertilizer because it contains high Nitrogen, Phosphorus and potassium (NPK) which are essential elements required in plant structures.

Enhancing sustainability and flavor of waste coconut (Cocos nucifera) kernel and sweet potato (Ipomoea batatas) peels Creamy roll: Extension program guide

Waste Coconut Kernels (WCK) and Sweet Potato (SP) peels are considered household wastes for animal feeding. The present study aimed to develop waste coconut kernel and sweet potato peels creamy roll as innovative guides for the Extension program guide. This experimental study used three formulations varying amounts of WCK with 100g, 150g and 200g; SP peels with 150g, 200g, and 250g mixed with milk solution, sugar and unsalted spring roll wrappers. The study focused on investigating the sensory attributes of the creamy roll development across different formulations, assessing its general acceptability in terms of color, flavor, odor and texture, identifying the most preferred formulation (F1, F2, and F3) based on the panel of tasters, and examining if there were significant differences among the product attributes. Based on Data analysis involved calculating weighted means and conducting One-way analysis of variance (ANOVA), the results revealed that F3, consisting of 250g of SP, 200g of WCK, 250g of milk solution, and 180g of sugar, was the most preferred in terms of flavor, odor and texture, with overall means of 3.67, 4.08, and 3.85, respectively. However, F2 was preferred only in color. A significant difference was observed in flavor indicated by a p-value of .042, lower than the predetermined alpha level of .05. Post-hoc analysis indicated differing perceptions between the 35 experienced consumers and 15 food experts. The most preferred formulation had a sensory acceptability rating of “acceptable” with a mean of 3.92. Based on the findings, the 250g SP peels and 200g WCK were adopted as an Extension program guide.

Impact of sweet potato peels extracts obtained by pulsed electric fields on the growth of probiotic strains from Lactobacillus genus

This work describes the first approach for the valorization of sweet potato (Sp) peels assisted by pulsed electric fields (PEF) to obtain extracts that enhance the growth of potential probiotic bacteria. Four different varieties were studied, namely white sweet potato (WSp, “O'Henry”), white with purple (WPSp or “Violeta Roja”), orange (OSp or “California”) and purple (PSp, “Pepita”). Among them, the PEF extracts obtained from PSp had a noticeable content of carbohydrates, polyphenols and flavonoids (12.5 mg/mL, 4.34 mg GAE/g and 1.73 mg GAE/g, respectively), being in any case higher than those obtained by maceration extraction. The analysis by quantitative Nuclear Magnetic Resonance (qNMR) allowed us to identify sucrose, fructose and glucose as the main sugars extracted, with a total concentration close to 94 mg/g PSp for the PSp-PEF crude extracts, which entails an enhancement by up to 92% with respect to the conventional extraction. Furthermore, these extracts improved the growth kinetics of probiotic bacteria, Lactobacillus members and also, the production of short chain fatty acids (SCFA). This fact should be also noted since they are considered valuable platform chemicals to be transformed into high-added-value, thus proposing another way for valorization. Industrial relevanceThe relevance of this work lies in the necessity of searching new sustainable foods for their consumption, and the processing of these foods by means of innovative technologies. In light with this fact, the suitability of PEF-assisted extraction to be scaled-up at industrial level would pave the way for an efficient, notable conversion of wasted sweet potato (Sp) peels to potential prebiotics, boosting the recovery of these compounds by PEF technology with respect to traditional extraction methods and the health benefits.

Carrageenan-based active and intelligent packaging films integrated with anthocyanin and TiO2-doped carbon dots derived from sweet potato peels

Carrageenan-based sustainable active and pH-dependent color-changing composite films were fabricated by blending anthocyanin extracted from sweet potato peel (SPA) with TiO2-doped carbon dots (Ti-CDs) prepared using the biowaste of SPA extraction. The SPA and Ti-CDs were compatible with the carrageenan matrix and were uniformly dispersed in the used polymer to form a homogeneous film with increased mechanical properties. The composite film added with SPA and 3 wt% Ti-CD showed 100 % UV protection, superb antioxidant (100 % DPPH and ABTS scavenging assay), and potent antibacterial activity (complete eradication of foodborne L.monocytogenes and E. coli strains after 3 h incubation). Additionally, the composite films showed distinguishable colorimetric responses to pH 7–12 buffers and volatile ammonia. The intelligent sensing ability of the composite film was assessed through shrimp freshness monitoring, and the film's hue shifted from pink (fresh shrimp) to yellow/brown (inedible shrimp) during storage. Shrimp packaging studies have shown that composite films retard the rate of food quality change during storage and are a good indicator of shrimp spoilage. Therefore, the designed film is expected to have high applicability as a chip, and quick on-site sensor that detects seafood quality in real-time, and a highly effective multifunctional film for better product quality preservation.

Adsorptive decolorization of dyes in aqueous solution using magnetic sweet potato (Ipomoea batatas L.) peel waste

Valorizing domestic biomass waste for contaminated water treatment may be an effective way to achieve the sustainable development goal of attaining clean water for all.

FORMULATION AND EVALUATION OF HAND AND BODY LOTION FROM PURPLE SWEET POTATO (IPOMOEA BATATAS L.) PEEL EXTRACT AND ITS ANTIOXIDANT ACTIVITY

Objective: This study aims to investigate the antioxidant activity of purple sweet potato (Ipomoea batatas L.) peel extract. The goal is to determine the levels of antioxidant activity in hand and body lotion formulas that use purple sweet potato peel extract as an antioxidant agent and to evaluate the formulas to identify the one with the best physical stability.
 Methods: The antioxidant activity was assessed using the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical inhibition method. Physical stability of the hand and body lotion formula was evaluated within 4 w storage at room temperature, the evaluation was based on measurements of various lotion characteristics such as organoleptic properties, pH, homogeneity, viscosity, phase separation, and spreadability.
 Results: The results of this study showed that the purple sweet potato peel extract exhibited antioxidant activity, with an IC50 value of 44.582±1.19 ppm. The antioxidant activity of the hand and body lotion formulas had IC50 values of 83.319±1.01, 63.181±0.97, and 24.107±0.63 ppm for formulas containing 1,3, and 5% extracts, respectively. The hand and body lotion formula containing 3% extract demonstrated the best physical stability, as it remained physically stable after being stored at room temperature for 4 w.
 Conclusion: The extract of purple sweet potato peel presented very strong antioxidant activity and has great potential for use in hand and body lotion formulas as an antioxidant agent.

Bound form terpenes in sweet potatoes and their distribution in flesh and peel of different cultivars

SummarySix prevalent sweet potato cultivars, New Orleans, Beauregard, Japanese, Hannah, Garnet and Jewel, were selected to determine the distribution of terpenes in their flesh and peel. Free‐form terpenes were not detected in both flesh and peel in all the cultivars by using a solid phase microextraction (SPME) and gas chromatography–mass spectrometer (GC–MS) method. Major terpenes in the sweet potatoes were linalool and α‐terpineol and existed in bound form in flesh and peel. They were released as free‐form and determined after acid hydrolysis treatment. However, ultrasonication‐assisted acid hydrolysis decreased the levels of terpenes with increased treatment time because the broken‐down free‐form terpenes were volatile and rapidly evaporated or oxidised. For the selected cultivars, the Garnet, Jewel and Japanese cultivars had the greatest levels of linalool, while the Beauregard and New Orleans cultivars had the greatest level of α‐terpineol. Also, the concentration of linalool or α‐terpineol in the peel of each cultivar was approximately two times greater than in its flesh. This study revealed the bound form terpenes and their distribution in sweet potatoes. The results explored the potential utilisation of sweet potato peel as a natural source of terpenes.

Eco-Friendly, High-Performance Humidity Sensor Using Purple Sweet-Potato Peel for Multipurpose Applications

Biomaterials offer great potential for enhancing the performance of humidity sensors, which play a critical role in controlling moisture levels across different applications. By utilizing environmentally friendly, sustainable, and cost-effective biomaterials, we can improve the manufacturing process of these sensors while reducing our environmental impact. In this study, we present a high-performance humidity sensor that utilizes purple sweet potato peel (PSPP) as both the substrate and sensing layer. The PSPP is chosen for its polar hydrophilic functional groups, as well as its environmentally friendly nature, sustainability, and cost-effectiveness. Remarkably, this humidity sensor does not require an external substrate. It exhibits a wide detection range of 0 to 85% relative humidity at various operating frequencies (100 Hz, 1 kHz, and 10 kHz) in ambient temperature, demonstrating its effectiveness in responding to different humidity levels. The sensor achieves a high sensitivity value of 183.23 pF/%RH and minimal hysteresis of only 5% at 10 kHz under ambient conditions. It also boasts rapid response and recovery times of 1 and 2 s, respectively, making it suitable for use in high-end electronic devices. Moreover, the sensor’s applications extend beyond environmental monitoring. It has proven effective in monitoring mouth and nasal breathing, indicating its potential for respiratory monitoring and noncontact proximity response. These findings suggest that sweet potato peel material holds great promise as a highly stable, non-toxic, biodegradable, cost-effective, and environmentally friendly option for various domains, including healthcare monitoring.

Utilization of purple yam skin (Ipomoea batatas L.) in the making of nata de batatas

Nata de batatas is a product of purple sweet potato peel. The presence of anthocyanin compounds in purple sweet potato skin makes this food very attractive to be processed into nata products that have functional value. The purpose of this research was to determine the yield of nata from purple sweet potato peel made with variations in the percentage of purple sweet potato peel extract and the percentage of coconut water and pellicle thickness, evaluate organoleptic properties including texture, color, aroma, taste, and determine anthocyanin levels. The results showed that the highest nata yield was 70.08%. The thickness of the largest 1.26 cm. The best anthocyanin analysis in nata was 0.47 mg. The organoleptic test showed that the color percentage of purple sweet potato peel extract and the percentage of coconut water were significantly different while the texture, aroma and taste were not significantly different.
 Keywords: nata de batatas, purple sweet potato skin, coconut water, anthocyanin

Sweet Potato Peel as Substitute Dietary Energy Source on the Early Laying Performance, Egg Quality Traits and Yolk Biochemical Composition of Japanese Quails (Coturnix coturnix japonica Temminck & Schlegel, 1898)

This study evaluated the potential of sweet potato peels from different varieties as substitute dietary energy in the early laying performance of Japanese quails. A total of 240 heads of ready-to-lay quails were laid out in a Randomized Complete Block Design (RCBD) and were assigned to the following treatments; ACommercial feeds, B-Home-mixed ration with 10% NISC Sp-35, C- Home-mixed ration with 10% NISC Sp-36, and D- Home-mixed ration with 10% Sp Japonita. The data were analyzed using one-way ANOVA for RCBD, and differences were determined using Tukey's Honestly Significant Difference Test (HSD) at p<0.05. The commercial diet improved hen-day egg production, FCR per dozen eggs, FCR per kilogram egg mass, and eggshell thickness. On the other hand, there were no significant differences (p>0.05) observed in egg weight, egg shape index, dry shell weight, yolk-albumen ratio and yolk total antioxidant activity. The yolk color score of HMR diets was significantly higher (p>0.05) and the yolk cholesterol deposition was lesser than those in the commercial diet. The financial analysis showed that the gross return was highest in the commercial ration. However, HMR diets performed better in terms of net income, return over feed cost, egg-to-feed price ratio, benefit-cost ratio, and return over investment.

Processing Purple Sweet Potato Peel as Alternative Material of Textile and Fashion Products with Circular Economic Principles

The textile and fashion industries are the most polluting industry in the world. This is because the industries driven by the fashion trend which is rapidly change. During the production and distribution process, the fashion and textile industries produce waste that can damage the air, water and soil. Moreover, the industries use non-renewable materials, and the life span of their product is short, eventually it will end up on the landfill. The application of circular economic principles on the textile and fashion industry is a step in an effort to reduce the level of environmental pollution. In this study, the principles that applied are, using biomaterial, obtain it from local resources, producing less waste, and after use the material can be naturally decomposed. The method used in this research is a qualitative method with an experimental approach. Data collected through a several exploration stages, processing purple sweet potato peel into composite materials. Processing purple sweet potato peel in this study is to produce an alternative raw material for the industries, so that they can use a more environmentally friendly material. Using biomaterials also can adding value to the textile and fashion products, so it can foster awareness to the consumer, in aim to make a systemic social behavioral change. The output of this study is the design of fashion products made of composite materials from purple sweet potato peel which are carried out using digital simulation sketches. The design was made based on the consideration of the character and potential of the composite material from the results of a series of experimental processes, so that the product sketch made is an accessory product consisting of earrings with a relatively small size.