Sweet Potato Waste Research Articles

Production of sweet potato distilled beverage: Economic evaluation via enzymatic and acid hydrolysis

AbstractThis study aimed to assess the feasibility of utilizing sweet potato waste for distilled beverage production in two process scenarios: (i) acid hydrolysis and (ii) enzymatic hydrolysis. Laboratory experiments were conducted using in natura sweet potato waste and the data obtained were used to design a production system capable of producing 1000 L of distillate per day. Net present value (NPV), internal rate of return (IRR), and discounted payback indicators were used for economic analysis, with a minimum attractiveness rate (MARR) of 15%. The initial investment for the projects was BRL 1 139 610.86 (USD 223 146.80) for enzymatic hydrolysis and BRL 1 314 824.54 (USD 257 455.36) for acid hydrolysis. Packaging costs were identified as the greatest expenses in the process. Assuming a selling price of BRL 14.50 (USD 2.84), the enzymatic hydrolysis process demonstrated an NPV of BRL 4 792 520.77 (USD 938 421.92) and IRR of 83.39%, and the acid hydrolysis process showed an NPV of BRL 2 191 636.78 (USD 429 143.68) and IRR of 42.49%. Consequently, establishing a production plant for distilled beverages proved to be more economically attractive when employing the enzymatic hydrolysis process and fermentation simultaneously, resulting in a return on investment within 1.46 years of operation. Upon scrutinizing the gain matrix, it became apparent that critical factors with the potential to affect the project's feasibility detrimentally, if increased, included the cost of acquiring packaging, the final volumetric fraction of the distilled beverage, and the tax rate. Nevertheless, an upturn in the selling price of the beverage and a process improvement yield both have the potential to underpin the project effectively.

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.

The benefits of purple sweet potato waste flour in the ratio of maintaining the quality of Lohmann brown chicken eggs

Lohmann brown chickens are laying hens as a source of egg supply. However, eggs are easily damaged if stored, it is necessary to improve egg quality, one of which can be done by utilizing purple sweet potato waste. This research aims to determine the effect of using purple sweet potato waste flour in rations on the quality of Lohmann brown chicken eggs stored for 5 weeks, carried out in Candiksuma Village, Melaya District, Jembrana Regency Bali for 12 weeks. The design used was a completely randomized design (CRD) consisting of 4 treatments and 4 replications. The treatment consisted of rations without purple sweet potato waste flour as a control (A), and rations containing 5% purple sweet potato waste flour (B), 10% (C), and 15% (D). Each experimental unit consisted of 10 chickens aged 65 weeks. After one month of treatment, 96 eggs were taken to be stored. The variables observed were egg weight, egg pH, egg specific gravity, egg yolk color, eggshell thickness, egg white percentage, egg yolk percentage, egg white index, egg yolk index, and haugh units (HU). The research results showed that giving purple sweet potato waste flour did not reduce egg quality in the variables of egg weight, egg pH, egg specific gravity, egg yolk percentage, egg white index, and egg yolk index during 5 weeks of storage. A decrease in egg quality occurs in egg yolk color, eggshell thickness, egg white percentage, and Haugh Units (HU). It can be concluded that providing purple sweet potato waste flour in the ration can maintain the quality of Lohmann brown chicken eggs stored for 5 weeks.

Potato waste and sweet potato waste utilization – some research trends

Potato waste and sweet potato waste utilization – some research trends

Starch-based edible protective coating obtained from sweet potato waste.

There is a need for sustainable solutions to increase shelf time and ensure food safety. The use of edible protective coatings in the food industry is and simple and innovative alternative, even more, when the coating is combined with active agents that confer additional functional attributes. Natural polymers such as polysaccharides are very interesting given their edibility, biodegradability, and easy access, among other aspects. Starch is one of the most widely used polysaccharides mainly due to its low cost and simplicity of processing technologies. In this work, sweet potato wastes were used to extract starch. This biopolymer was combined to develop an edible film, by gelation process. The edible coating was characterized in terms of surface morphology (SEM), chemical composition (FTIR) and wettability. For the protective effect, different fruits (bananas, apples, passion fruit, tomato and guava) were coated with 1 or 2 layers of this film. The results showed, in general, that the coated samples revealed better results regarding, texture, color, odor and delayed maturation when compared to the uncoated controls. This is indicative of the potential for increased shelf-time of fruits without significant alterations to their intrinsic properties. Moreover, the extraction process, based on food waste recovery and circularity combined with the protective effect shows the importance of this work and its alignment with several sustainable development goal.

Production of ornamental fish in a biofloc-based system using sweetpotato (Ipomoea batatas) waste as carbon source

The use of biofloc technology has positive effects on the quality of water and utilization of feed through the recycling microbial protein during the culture of commercially important finfishes. This culture technology is also used in the rearing of ornamental fish to address limitations on land space and water use as well to minimize the impacts of wastewater discharge. Therefore, the current study evaluated the utilization of plant wastes in the production of biofloc for the ornamental fish culture. A 30-day trial was conducted to evaluate the effects of using sweetpotato, Ipomoea batatas wastes in biofloc production for the rearing of molly, Poecilia sp. The effects on growth, water quality and bacterial population in the water were evaluated. Triplicate tanks of water supplemented with dried sweetpotato wastes (biofloc treatment) at a C:N ratio of 10 and the non-biofloc group were stocked with mixed-sex juveniles of molly at a density of 3 fish per liter and reared for 30 days. Significant differences were observed in water quality parameters particularly lower concentrations of ammonia and nitrate in the biofloc group. Growth parameters showed better growth and lower feed conversion rate in the biofloc group. Higher bacterial counts were also observed in the biofloc group than in the control. The current study showed that sweet potato wastes could be used in the production of biofloc during the rearing of ornamental fish and the presence of bioflocs can increase bacterial population in the water resulting in the recycling of nutrients that could lead towards improving water quality and enhancing fish growth.

Structural Properties of Bacterial Cellulose Film Obtained on a Substrate Containing Sweet Potato Waste

The paper presents the results of research on the microstructure of bacterial cellulose (BC-SP) obtained on a medium containing sweet potato peel, which was compared to cellulose obtained on a synthetic medium containing sucrose and peptone (BC-N). The properties of cellulose were analyzed using the methods: size exclusion chromatography (SEC), X-ray diffraction (XRD), scanning electron microscope (SEM), and computer microtomograph (X-ray micro-CT). BC-SP was characterized by a higher degree of polymerization (5680) and a lower porosity (1.45%) than BC-N (4879, 3.27%). These properties give great opportunities to cellulose for various applications, e.g., the production of paper or pulp. At the same time, for BC-SP, a low value of relative crystallinity was found, which is an important feature from the point of view of the mechanical properties of the polymer. Nevertheless, these studies are important and constitute an important source of knowledge on the possibility of using cheap waste plant materials as potential microbiological substrates for the cultivation of cellulose-synthesizing micro-organisms with specific properties.

Response of Native Chickens (3-10 Weeks) Fed on Diets Substituated With Graded Levels of Sweet Potato Fermentation

The purpose of this study was to determine the effect of giving fermented sweet potato waste in the ration on the appearance of native chickens aged 3 - 10 weeks and to find out what percentage of the level of use of fermented sweet potato waste in the ration. This study used a completely randomized design (CRD) with 5 treatments and 3 replications. The treatments consisted of: R0 = ration without additional fermented sweet potato waste as control, R1 = ration containing 3% unfermented sweet potato was, R2 = ration containing 3% fermented sweet potato waste, R3 = ration containing 6% fermented sweet potato waste, R4 = The ration contains 9% fermented sweet potato waste. Each replication (experimental unit) used 5 native chickens so that the number of chickens used was 75. The use of sweet potato waste fermentation in the ration had no significant effect (P>0.05) on initial body weight, final body weight , weight gain,and feed convertion ratio. Feeding of fermented sweet potato waste to a level of 3% (R2) gave optimal results.

Experimental assessment on preparation of biodegradable polythylene/polylatic acid-chithosan composite from renewable resources

Due to poor degradability and contamination risk of synthetic plastics, utilization of renewable resources is encouraged. Biobased thermoplastic polymers from renewable resource that is inexpensive, biodegradable, compostable and renewably non-toxic, is focused. In this paper mixtures of synthetic and natural polymers were used as a potential option to reduce pollution by plastic waste. The study is aimed at assessing utilization of sweet potato waste as a source of bioplastic for package application, the polymer was modified with a biopolymer chitosan to obtain polylactic acid-chitosan plastic. The developed polymer matrix was blended with polyethylene to obtain biodegradable packaging material. The bioplastic was characterized using Fourier Transformed Infra-Red Spectroscopy (FTIR) and scaning electron microscope (SEM). Physical and mechanical properties of the composites were evaluated by measuring enzymatic degradation, tensile strength, and elongation at break. The results have shown that the film obtained have homogeneous surface by (SEM). Mechanical properties of the bio plastics revealed that tensile strength increases with increases in the concentration of chitosan and hence, the elongation at break decreases with increase in chitosan content. While the fastest enzymatic degradation was observed to have high microbial growth on the bio plastics with high content of Chitosan-Polylactic acid.

Engineering Cupriavidus necator DSM 545 for the one-step conversion of starchy waste into polyhydroxyalkanoates

Starch-rich by-products could be efficiently exploited for polyhydroxyalkanoates (PHAs) production. Unfortunately, Cupriavidus necator DSM 545, one of the most efficient PHAs producers, is not able to grow on starch. In this study, a recombinant amylolytic strain of C. necator DSM 545 was developed for the one-step PHAs production from starchy residues, such as broken rice and purple sweet potato waste. The glucodextranase G1d from Arthrobacter globiformis I42 and the α-amylase amyZ from Zunongwangia profunda SM-A87 were co-expressed into C. necator DSM 545. The recombinant C. necator DSM 545 #11, selected for its promising hydrolytic activity, produced high biomass levels with noteworthy PHAs titers: 5.78 and 3.65 g/L from broken rice and purple sweet potato waste, respectively. This is the first report on the engineering of C. necator DSM 545 for efficient amylase production and paves the way to the one-step conversion of starchy waste into PHAs.

Utilization Of Organic Fertilizer Compost Made From Purple Sweet Potato Waste (Ipomoea Batatas L.) To Increase The Production Of Pakchoy (Brassica Chinensis L.)

Compost is an organic fertilizer made from recycled organic materials. Fertilizers can be made from organic waste or unused organic waste. Purple sweet potato waste can be reused into compost. The purpose of this study was to examine the effectiveness of purple sweet potato waste compost inoculated with Trichoderma harzianum in increasing the production of pakchoi and to determine the treatment of purple sweet potato waste compost to increase the production of pakchoi. The research method used is the experimental method. The experimental design used was RAK (Randomized Block Design) with 1 factor. The experiment consisted of 4 treatments of purple sweet potato compost 25 (B) g, 50 g (C), 75 g (D), 150 g (E), and 1 control (A), and was repeated 5 times. The data analysis technique used analysis of variance (ANOVA). Parameters observed were the number of leaves, plant height, leaf width, plant wet weight, plant dry weight, and root length. The results showed that the application of purple sweet potato compost affected increasing the growth and production of pakchoi. The right treatment in increasing the growth of pakchoi is treatment 150 g or treatment E. Treatment 150 g (E) can increase the number of leaves (13.13), plant height (16.32 cm), leaf width (4.88 cm), wet weight (16.60 g), dry weight (6.35 g), and root length (15.80 cm).

Refining of vegetable waste to renewable sugars for ethanol production: Depolymerization and fermentation optimization

The study evaluates the potential of different vegetable wastes namely, composite vegetable waste (CVW), potato waste (PW), sweet potato waste (SPW) and yam waste (YW) as an alternative feedstock for the production of renewable sugars. Thermal assisted chemical pretreatment followed by enzymatic saccharification yielded maximum sugars (0.515 g/g CVW, 0.56 g/g PW, 0.57 g/g SPW and 0.56 g/g YW) with total carbohydrate depolymerization of 95.01%, 88.30%, 90.32% and 88.59% respectively. Obtained sugars were valorized into bioethanol through fermentation using S. cerevisiae by optimizing the pH and temperature. The highest ethanol yield of 251.85 mg/g was obtained from SPW at 35°C followed by YW (240.98 mg/g), PW (235.4 mg/g) and CVW (125.6 mg/g) at pH 5.0. Utilizing the abundantly available vegetable wastes as a renewable feedstock for reducing sugars and subsequent bioethanol production will influence the economics and sustainability of the process positively in circular biorefinery format.

Effect of different levels of Ipomoea batatas flour inclusion on the ruminal pH of sheep in metabolic cages

The accumulation of industrial by-products increases the use of sweet potato waste for ruminants, but ruminal pH characteristics are still not well known. The objective was to assess the fluctuation of ruminal pH in sheep supplemented with different levels of sweet potato flour inclusion in their diet. Four rumen-fistulated sheep were used; they were fed a diet based on ryegrass haylage (Lolium multiflorum) and sweet potato flour (Ipomoea batatas), provided according to the level of inclusion in the total diet (0, 0.5, 1.0 and 1.5%). Approximately 80 ml of ruminal fluid was collected for reading on a bench pH meter. Statistical data analysis was run on Statistical Analysis System (SAS Institute INC. Cary, NC, USA), and statistical difference was considered for p < 0.05. The animals that received 1.5% of sweet potato flour in their diet presented acid rumen pH; the 1.0% group presented rumen pH acidification in the first 6 hours after feeding, and the 0.5% level of inclusion did not change the rumen environment. It is concluded that the inclusion of 0.5% sweet potato flour in sheep diet proved to be an efficient energy supplementation strategy.

Integrated Efforts for the Valorization of Sweet Potato By-Products within a Circular Economy Concept: Biocomposites for Packaging Applications Close the Loop

With the aim to fully exploit the by-products obtained after the industrial extraction of starch from sweet potatoes, a cascading approach was developed to extract high-value molecules, such as proteins and pectins, and to valorize the solid fraction, rich in starch and fibrous components. This fraction was used to prepare new biocomposites designed for food packaging applications. The sweet potato residue was added to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in various amounts up to 40 wt % by melt mixing, without any previous treatment. The composites are semicrystalline materials, characterized by thermal stability up to 260 °C. For the composites containing up to 10 wt % of residue, the tensile strength remains over 30 MPa and the strain stays over 3.2%. A homogeneous dispersion of the sweet potato waste into the bio-polymeric matrix was achieved but, despite the presence of hydrogen bond interactions between the components, a poor interfacial adhesion was detected. Considering the significant percentage of sweet potato waste used, the biocomposites obtained show a low economic and environmental impact, resulting in an interesting bio-alternative to the materials commonly used in the packaging industry. Thus, according to the principles of a circular economy, the preparation of the biocomposites closes the loop of the complete valorization of sweet potato products and by-products.

AVAILABILITY AND UTILIZATION OF AGRICULTURAL FOOD AS A SOURCE OF BALI BEEF IN MOWEWE SUB-DISTRICT, EAST KOLAKA

This study aims to analyze the availability and utilization of agricultural by-products as a source of feed for Balinese cattle in Mowewe District, East Kolaka Regency. The research was conducted in March-May 2020. The research respondents involved 83 cow breeders. The data analysis used is descriptive analysis. The availability of agricultural food waste feed is calculated based on the formula Muller et al. (1974). The variables observed were the type of feed from agricultural byproducts and the potential availability of agricultural by-products as feed for Bali cows in Mowewe Sub-district, East Kolaka Regency. The results showed thatwith the production of forage BK/Ha 167602.80 tons/year. The availability and use of agricultural by-products as a source of feed for Bali cattle include:Type of feed from agricultural by-products, namely rice straw, sweet potato, maize and peanuts. Potential availability of agricultural by-products as feed, namely, agricultural by-products in the research location for producing rice straw.2073.75 tons/year, 6000 tons/year of sweet potato waste, 54000 tons of corn waste/year and 6000 tons of peanut waste/year.

Investigation of Mannich reaction during co-liquefaction of microalgae and sweet potato waste: Combustion performance of bio-oil and bio-char

Microalgae (MA) was co-liquefied with sweet potato waste (SPW) to improve bio-oil and bio-char qualities via Mannich reaction. The influence of Mannich reaction on combustion performances of bio-oil and bio-char were investigated. Results suggested that the addition of SPW decrease the ignition temperature of bio-oil from 186.6 °C to 165.0 °C. In addition, the denitrification effect of Mannich reaction can decrease the HCN and NO emission of bio-oil, contributing to reducing pollutant emission. As for bio-char, Mannich reaction improved the combustible material content in bio-char, which decreased the risk of slagging problem. The comprehensive combustion indexes of bio-oil (1.23 × 10−6 × min−2×°C−3) and bio-char (4.79 × 10−8 × min−2×°C−3) from co-liquefaction were higher than those from liquefaction of MA (0.91 × 10−6 × min−2×°C−3 for bio-oil and 1.24 × 10−8 × min−2×°C−3 for bio-char), indicating that the combustion performance was promoted by adding SPW. Overall, Mannich reaction can be applied to improve the combustion performance of bio-oil and bio-char.

Conversion of Starchy Waste Streams into Polyhydroxyalkanoates Using Cupriavidus necator DSM 545.

Due to oil shortage and environmental problems, synthetic plastics have to be replaced by different biodegradable materials. A promising alternative could be polyhydroxyalkanoates (PHAs), and the low-cost abundant agricultural starchy by-products could be usefully converted into PHAs by properly selected and/or developed microbes. Among the widely available starchy waste streams, a variety of residues have been explored as substrates, such as broken, discolored, unripe rice and white or purple sweet potato waste. Cupriavidus necator DSM 545, a well-known producer of PHAs, was adopted in a simultaneous saccharification and fermentation (SSF) process through an optimized dosage of the commercial amylases cocktail STARGEN™ 002. Broken rice was found to be the most promising carbon source with PHAs levels of up to 5.18 g/L. This research demonstrates that rice and sweet potato waste are low-cost feedstocks for PHAs production, paving the way for the processing of other starchy materials into bioplastics.

Flotation-based dye removal system: Sweet potato protein fabricated from agro-industrial waste as a collector and frother

Hazardous synthetic dyes have emerged as an imperative issue of water contamination. This investigation focused on the development of a green flotation-based dye removal (FBDR) system to remove trace crystal violet (CV). A natural protein derived from sweet potato waste which was a readily available and low-cost agro-industrial residual was utilized as the collector and frother, due to its biodegradability and nontoxicity. In the first-stage of FBDR, an inclined foam channel with hydrophobic surface was employed to continuously recover sweet potato protein (SPP). Its recovery percentage and volume ratio reached 84.7 ± 4.2% and 7.2 ± 0.4, respectively. Enriched SPP (10.4 ± 0.5 g/L) was then collected by isoelectric precipitation and freeze drying. Encouragingly, SPP induced the desirable foaming and stable bubbles of the solution. Analytical tests, including SEM, FTIR, UV–vis spectra, and fluorescence measurements, confirmed that the SPP-CV complex was formed mainly through the hydrophobic force. In the second-stage, an excellent CV removal was generated with the collection of SPP. The removal efficiency and enrichment ratio of CV were 95.8 ± 4.5% and 9.2 ± 0.4, respectively. The kinetic study indicated that the removal rate markedly increased with increasing air flowrate. In conclusion, this investigation demonstrated the waste protein could be an effective, inexpensive and eco-friendly alternative for classical collector and/or frother, and provided new insights into the disposal of dye wastewaters.

Food waste biorefinery advocating circular economy: Bioethanol and distilled beverage from sweet potato

The exponential growth rate of the global population has been causing a threat to finite resources and also increasing the amount of waste generated. The global quantitative food waste for tubers is 45% per year, which in Brazil would amount to 350,000 tons of sweet potato wasted annually. Food waste causes 10% of the emissions of greenhouse gases. In this work, food waste biorefineries are the proposed solution. Integrated processing via a combination of different technologies to produce both ethanol and distilled beverage was evaluated to valorize sweet potato waste profitably within the circular economy concept. No works concerning the integrated production of both products simulating different real market scenarios were found. Five different scenarios varying the production percentage of each product were evaluated. The higher the production of the distilled beverage, the more profitable the scenarios are. Economic results began to be positive when the production for sale of each product reaches 40%, plus 20% of ethanol for domestic consumption. The scenario with 80% of beverage production presented NPV of US$ 1,078,500.18, IRR of 51%, and discounted payback of 1.06 years. The sweet potato waste biorefinery is a sustainable model and contributes to the development of the agriculture and food sector by providing new businesses and consequent job creation. It also leads to the reduction of greenhouse emissions by producing renewable resources and marketable products, thus reaching the goals of the circular economy.

A circular economy model for ethanol and alcohol-based hand sanitizer from sweet potato waste in the context of COVID-19

Goal: The goal of the present work is to analyze the techno-economic viability of a biorefinery to generate ethanol and alcohol-based hand sanitizer from sweet potato waste within the concept of a circular economy.
 Design / Methodology / Approach: A survey of expenses for a 1000 L.day-1 distilled plant was carried out, and five different market scenarios were evaluated, varying the rate of production of each product.
 Results: Results show that the higher the production of the hand sanitizer, the more lucrative the scenarios are. The economic breakeven point occurs when the percentage of the alcohol-based hand sanitizer production is equal to 34%. However, the project becomes economically attractive from the production rate of 39%. The scenario for 80% of alcohol-based hand sanitizer production resulted in NPV of US$ 913,140.92, IRR of 64%, with a discounted payback of 0.72 year.
 Limitations of the investigation: It was considered that all the production was sold, which is in line with the current market demand. However, if the market slows down, the sales and the revenue obtained may be lower.
 Practical implications: The production of hand sanitizer from sweet potato waste is an opportunity to meet the market needs in scenarios such as the COVID-19 pandemic. Besides, the proposed biorefinery promotes the development of the circular economy through waste minimization.
 Originality / Value: No studies about the production of ethanol and alcohol-based hand sanitizer from sweet potato waste in an integrated way, and the simulation of different real market scenarios were found.