The Sustainability of Sweet Potato Residues from Starch Processing By-Products: Preparation with Lacticaseibacillus rhamnosus and Pediococcus pentosaceus, Characterization, and Application.

The effects of Lacticaseibacillus rhamnosus and Pediococcus pentosaceus on the nutritional-functional composition, structure, in vitro saliva-gastrointestinal digestion, and colonic fermentation behaviors of fermented sweet potato residues (FSPR) were investigated. The FSPR was obtained under the condition of a solid-to-liquid ratio of 1/10, inoculation quantity of 1.5%, mixed bacteria ratio 1:1, fermentation time of 48 h, and fermentation temperature of 37 °C. The FSPR showed higher contents of soluble dietary fiber (15.02 g/100 g), total polyphenols content (95.74 mg/100 g), lactic acid (58.01 mg/g), acetic acid (1.66 mg/g), volatile acids (34.26%), and antioxidant activities. As exhibited by FTIR and SEM, the higher peak intensity at 1741 cm-1 and looser structure were observed in FSPR. Further, the FSPR group at colonic fermentation time of 48 h showed higher content of acetic acid (1366.88 µg/mL), propionic acid (40.98 µg/mL), and butyric acid (22.71 µg/mL), which were the metabolites produced by gut microbiota using dietary fiber. Meanwhile, the abundance of Bifidobacterium and Lacticaseibacillus in the FSPR group was also improved. These results indicated that FSPR potentially developed functional foods that contributed to colonic health.

Nutritional composition, antioxidant activity, volatile compounds, and stability properties of sweet potato residues fermented with selected lactic acid bacteria and bifidobacteria.

The effects of four kinds of lactic acid bacteria (LAB) and one bifidobacteria on nutritional composition, antioxidant activity, volatile compounds and stability properties of fermented sweet potato residues (SPR) were investigated. The soluble dietary fiber (12.92-16.63 g/100 g DW), total polyphenols content (90.51-97.35 mg/100 g DW), organic acids, and stability of SPR were increased after fermentation. The DPPH radical scavenging capacity (39.49-62.04 mg AAE/100 g DW) and ferric reducing antioxidant power (47.14-71.87 mg TE/100 g DW) were also increased, of which SPR fermented with Lacticaseibacillus rhamnosus CICC 23119 exhibited the highest values. Meanwhile, the anti-nutritional compound (oxalic acid) was decreased from 0.46 to 0.08-0.30 mg/g DW. Also, the fermented SPR exhibited different flavors compared with SPR, due to the production of acids especially antiseptic hexanoic acid and sorbic acid. Therefore, these results can provide a theoretical basis for the high-value utilization of SPR.

Evaluation of texture, retrogradation enthalpy, water mobility, and anti-staling effects of enzymes and hydrocolloids in potato steamed bread.

The functionalities of hydrocolloids and enzymes in texture, retrogradation enthalpy, water mobility and distribution, and anti-staling effects of potato steamed bread stored for 0, 24, and 48 h at 25 °C were investigated. Four kinds of hydrocolloids, including carrageenan, xanthan gum, arabic gum, sodium alginate, and one kind of enzyme (xylanase) showed little effects on the hardness reduction and springiness retention of potato steamed bread during storage, while the presence of α-amylase and lipase could slow down its staling rate. Potato steamed bread with combination of α-amylase (20 mg/kg) and lipase (40 mg/kg) exhibited the lowest hardness, with a significant reduction of 44.20%, besides improving the specific volume, L*, and overall acceptability in sensory evaluation. The addition of α-amylase and lipase could decrease the retrogradation enthalpy and bound water, and increase the mobility of mobile water. These findings shed efficient methods to retard staling of potato steamed bread.

Identification of saprophytic microorganisms and analysis of changes in sensory, physicochemical, and nutritional characteristics of potato and wheat steamed bread during different storage periods.

Due to its nutritional value and no gluten, potato flour has recently been used as a new type of material to make steamed bread. However, compared to traditional wheat steamed bread, its shelf life is considerably shorter, the dominant microorganisms and storage properties also differ. High-throughput sequencing combined with molecular biology assay revealed that Bacillus methylotrophic and Bacillus subtilis were the dominant bacteria in the crumb of potato and wheat steamed bread, respectively. Moreover, Meyerozyma, Penicillium chrysogenum, Penicillium citrinum, and Aspergillus parasiticus were the main fungi in the crusts. Ethanol was the most volatile compound in fresh potato and wheat steamed bread. Following storage for 48 h, 2,3-butanediol and 3-hydroxy-2-butanone were established as the most volatile compounds. Although decreased sourness was observed, the specific volume, brightness, and nutritional composition remained nearly unchanged. These findings provide a valuable theoretical basis for the development of potato and wheat steamed bread preservation technologies.

Effects of particle size on structural, physicochemical, and functional properties of potato residue from starch isolation and quality characteristics of residue-based starch noodles.

The structural, physicochemical, and functional properties of potato residue with different mesh sizes (<180 µm, <150 µm, <106 µm, <75 µm, ultrafine) obtained from starch isolation were investigated, and its effects on the shear strength, tensile strength, cooking time, and in vitro digestibility of 5% potato residue-based starch noodles were further compared. The results showed that the protein, ash, dietary fiber, water holding capacity, and water solubility of fractionated potato residue were decreased with decreasing particle size, while the starch, fat, polyphenols, and α-amylase activity inhibition ratio were increased. Ultrafine particles exhibited the highest phenolic content (2.26 mg chlorogenic acid equivalent/g), glucose adsorption capacity (7.03 mmol/g), cholesterol adsorption capacity (16.54%), and better performance on starch noodles formulation. However, oil holding capacity and microstructure did not show any significant differences. Therefore, potato residues with desired particle sizes could be successfully used to develop fiber-enriched food products for reducing food waste.

Effect of high hydrostatic pressure-assisted pectinase modification on the Pb2+ adsorption capacity of pectin isolated from sweet potato residue.

Novel pectin derived from sweet potato residue was modified by high hydrostatic pressure (HHP)-assisted pectinase and then used for Pb2+ removal from aqueous solutions. The removal characteristics and mechanisms were also investigated. Results showed that modified sweet potato pectin exhibited greater adsorption performances for Pb2+ than that of natural ones, and showed excellent eco-friendly properties and good potential for adsorption of some other heavy metals (such as Cu2+). The adsorption curves were much more conformed to Langmuir model, and the highest capacity for Pb2+ adsorption was 263.15 mg/g with 1.00% pectin at pH 7. Chemical adsorption process of pectin for Pb2+ absorption involved O-containing functional groups (O-H, COO-), cation exchange, and along with electrostatic interactions. Overall, the results in this study indicated that sweet potato pectin modified with HHP-assisted pectinase had the potential to become an environmentally friendly coagulant-flocculant agent for the heavy metal adsorption, especially for Pb2+.

Structural, physicochemical and emulsifying properties of sweet potato pectin treated by high hydrostatic pressure and/or pectinase: a comparative study.

BACKGROUND: Sweet potato (Ipomoea batatas L.) is the sixth most important food crop in the world, and China is the largest producer. Large amounts of sweet potato residues are generated during starch extraction, leading to environmental pollution and resource waste. However, these residues can be used as a viable source for pectin extraction. As a natural biopolymer with high molecular weight and complex structure, the usefulness of pectin has been limited, and it needs to be modified in order to improve its physicochemical properties, thus expanding its applications in the food industry. Therefore, the reported study was conducted to modify sweet potato pectin (SPP) using high hydrostatic pressure (HHP) and/or pectinase treatment, and to determine the effects of such treatment on structural, physicochemical and emulsifying properties. RESULTS: The results demonstrated that the molecular weight of SPP decreased following HHP and pectinase treatment, which was evidenced using scanning electron microscopy and atomic force microscopy. The degree of esterification was also decreased, confirmed by decreased intensity of the peak at 1739 cm-1 in the Fourier transform infrared spectrum and decreased peaks at 3.6 and 3.8 ppm in the 1 H NMR spectrum. Moreover, the content of monosaccharides and uronic acids increased and emulsifying properties improved after HHP and pectinase treatment. CONCLUSIONS: HHP-assisted pectinase treatment could be used as novel technique for the modification of pectin to give better emulsifying properties with great potential for application in the food industry. © 2020 Society of Chemical Industry.

Effects of ionic polysaccharides and egg white protein complex formulations on dough rheological properties, structure formation and in vitro starch digestibility of wet sweet potato vermicelli.

Effects of ionic polysaccharides [chitosan (C), sodium alginate (A) and xanthan (X)] and egg white protein (EP) complex formulations on dough rheology, structure formation and in vitro starch digestibility of wet sweet potato vermicelli (SPV) were investigated. Linear viscoelastic region (LVR) with low strain level of 0.015-0.036% were observed for all starch doughs with different complex formulations. Starch doughs complexed with A-X, C-EP, A-EP and X-EP exhibited lower degree of dependence of G' on frequency sweep and maximum creep compliance in creep-recovery test, followed by those with C-A-EP and A-X-EP, suggesting stable network structure formation. Wet SPV with C-A exhibited the strongest tensile strength (1.99 g/mm2), followed by those with C-EP and C-A-EP (1.51 and 1.58 g/mm2), and all showed high tensile distance (91.00%, 77.92% and 66.91%) and cooking break time (46.0, 45.5 and 48.5 min) respectively. Evenly distributed air cells with smaller pore sizes were formed, and compacted patterns of starch molecules were presented in all wet SPV with different complex formulations. Wet SPV with C-A-EP showed lower rapidly digestible (31.42%) but higher resistant starch (61.59%) content compared to other formulations. Thus, complex formulations of C-A, C-EP and C-A-EP show great application potential in wet SPV with high quality.

Effects of different polysaccharides and proteins on dough rheological properties, texture, structure and in vitro starch digestibility of wet sweet potato vermicelli.

The effects of polysaccharides (chitosan, xanthan and sodium alginate) and proteins (gluten, egg white protein) on dough rheological properties, texture, structure and in vitro starch digestibility of wet sweet potato vermicelli (SPV) were investigated. All starch doughs exhibited a linear viscoelastic region (LVR) of <0.05% strain. Chitosan, sodium alginate and xanthan incorporated dough exhibited lower maximum creep compliance and degree of dependence of G' on frequency sweep than those with egg white protein and gluten, suggesting the formation of stable network structure with stronger deformation resistance. Wet SPV with chitosan exhibited the highest tensile strength, tensile distance and cooking break time, followed by sodium alginate, xanthan, egg white protein and gluten. A mass fracture structure and evenly distributed air cells with similar pore sizes were formed in all wet SPV. Physical linkages between starch and polysaccharides or proteins in all wet SPV were confirmed by similar FTIR spectra. Xanthan and sodium alginate addition decreased the rapidly digestible starch, and increased the resistant starch in wet SPV. In conclusion, all polysaccharides and proteins can improve the quality of wet SPV, and xanthan, sodium alginate and egg white protein show greater application potential.

Optimization of ultrasound-microwave assisted acid extraction of pectin from potato pulp by response surface methodology and its characterization.

The ultrasound-microwave assisted HCl extraction of pectin from potato pulp was optimized using the response surface methodology. Effects of extraction temperature, pH, and time on the yield were evaluated, and structural characteristics of pectin extracted under optimal conditions were determined. The yield was 22.86 ±â€¯1.29% under optimal conditions of temperature 93 °C, pH 2.0, and time 50 min. The obtained pectin was rich in branched rhamnogalacturonan I (61.54 mol%). Furthermore, the pectin was a low-methoxyl (degree of methylation, 32.58%) but highly acetylated (degree of acetylation, 17.84%) pectin and the molecular weight was 1.537 × 105 g/mol. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance indicated that pectin had a linear region of α-1, 4-linked galacturonic acids which could be methyl and acetyl-esterified, and rhamnose linked with galacturonic acid to form rhamnogalacturonan which was branched with side chains. Scanning electron microscopy showed most of pectin had a lamellae structure.

Optimization of processing technology using response surface methodology and physicochemical properties of roasted sweet potato.

The study evaluated the optimal condition for roasting sweet potato using response surface methodology. Proximate composition, antioxidant activity, volatile compounds, and water migration of roasted sweet potato were also determined. The results revealed that the optimal roasting condition included a roasting time of 40 min, a roasting temperature of 235 °C, and a roasting speed of 40 rad/min, the reducing sugar and vitamin C of roasted sweet potato obtained under optimal condition was 47.79 g/100 g (DW) and 60.25 mg/100 g (DW), respectively. After roasting, starch, protein and vitamin C content of sweet potato were significantly decreased, while total phenolic content and antioxidant activity were increased. 2-Methyl butanal was the main aromatic compound. Low-field NMR indicated that the proportion of free water increased and relaxation times (T2) were decreased after roast process, indicated that the bound water in sweet potato was diffused from inside to outside, thus the texture became softer.

Extraction, structure, and emulsifying properties of pectin from potato pulp.

Effects of HCl, H2SO4, HNO3, citric acid, and acetic acid on the yield, structure, and emulsifying properties of potato pectins were investigated. Results showed that the highest yield (14.34%) was obtained using citric acid, followed by HNO3 (9.83%), HCl (9.72%), H2SO4 (8.38%), and acetic acid (4.08%). The degrees of methylation (37.45%) and acetylation (15.38%), protein content (6.97%), and molecular weight (3.207 × 105 g/mol) were the highest for pectin extracted using acetic acid, and (galactose + arabinose)/rhamnose was 33.34, indicating that it had a highly branched rhamnogalacturonan I domain. Fourier transform infrared spectroscopy showed a specific absorbance peak at 1064 cm-1, which corresponds to the acetyl groups in potato pectins. SEM showed that all potato pectins are morphologically different. The emulsifying activity (EA, 44.97%-47.71%) and emulsion stability (ES, 36.54%-46.00%) of the pectins were influenced by acid types, and were higher than those of commercial citrus and apple pectin.

Modification of deoiled cumin dietary fiber with laccase and cellulase under high hydrostatic pressure.

In this study, we evaluated the effects of high hydrostatic pressure (HHP) and enzyme (laccase and cellulase) treatment on the structural, physicochemical, and functional properties and antioxidant activity of deoiled cumin dietary fiber (DF). HHP-enzyme treatment increased the contents of soluble dietary fiber (SDF) (30.37 g/100g), monosaccharides (except for glucose), uronic acids, and total polyphenol. HHP-enzyme treatment altered the honey-comb structure of DF and generated new polysaccharides. DF modified by HHP-enzyme treatment exhibited improved water retention capacity (10.02 g/g), water swelling capacity (11.19 mL/g), fat and glucose absorption capacities (10.44 g/g, 22.18-63.54 mmol/g), α-amylase activity inhibition ration (37.95%), and bile acid retardation index (48.85-52.58%). The antioxidant activity of DF was mainly correlated to total polyphenol content (R=0.8742). Therefore, DF modified by HHP-enzyme treatment from deoiled cumin could be used as a fiber-rich ingredient in functional foods.

Effects of extraction methods and particle size distribution on the structural, physicochemical, and functional properties of dietary fiber from deoiled cumin.

This study evaluated the effects of alkali extraction, enzymatic hydrolysis, shear emulsifying assisted enzymatic hydrolysis, and particle size distribution on the chemical composition and the structural, physicochemical, and functional properties of deoiled cumin dietary fibers (AEDF, EHDF and SEDF). Compared to AEDF and EHDF, SEDF had the highest total dietary fiber, crystalline regions, water swelling capacity (6.79-7.98ml/g), oil adsorption capacity (6.12-7.25%), α-amylase activity inhibition ratio (14.79-21.84%), glucose adsorption capacity (2.02-60.86%), and bile acid retardation index (16.34-50.08%). DFs sieved with mesh sizes >80 exhibited better physicochemical and functional properties than unsieved DFs. The physicochemical properties of sieved DFs improved with increasing sieve mesh sizes (40-120), but decreased with sieve mesh sizes >120, while the functional properties increased with increasing sieve mesh sizes. SEDF sieved with mesh sizes 100-150 can be used as functional ingredients due to its excellent physicochemical and functional properties.

Optimization of extraction efficiency by shear emulsifying assisted enzymatic hydrolysis and functional properties of dietary fiber from deoiled cumin (Cuminum cyminum L.).

This study evaluated the optimal conditions for extracting dietary fiber (DF) from deoiled cumin by shear emulsifying assisted enzymatic hydrolysis (SEAEH) using the response surface methodology. Fat adsorption capacity (FAC), glucose adsorption capacity (GAC), and bile acid retardation index (BRI) were measured to evaluate the functional properties of the extracted DF. The results revealed that the optimal extraction conditions included an enzyme to substrate ratio of 4.5%, a reaction temperature of 57 °C, a pH value of 7.7, and a reaction time of 155 min. Under these conditions, DF extraction efficiency and total dietary fiber content were 95.12% and 84.18%, respectively. The major components of deoiled cumin DF were hemicellulose (37.25%) and cellulose (33.40%). FAC and GAC increased with decreasing DF particle size (51-100 µm), but decreased with DF particle sizes <26 µm; BRI increased with decreasing DF particle size. The results revealed that SEAEH is an effective method for extracting DF. DF with particle size 26-51 µm had improved functional properties.