Aseptic Processing of Sweetpotato Purees Using a Continuous Flow Microwave System

ABSTRACT: Sweetpotato purees (SPP) were aseptically processed using a continuous flow microwave system to obtain a shelf-stable product. The dielectric properties of SPP were measured, and the dielectric constant and loss factor were within the range of the published values for fruits and vegetables. Small-scale tests were conducted in a 5-kW microwave unit to determine changes in color and viscosity with different thermal treatments. The results of these tests showed that color values (L*, a*) and viscosity did not change significantly compared with the untreated control. Pilot-scale tests were then conducted in a 60-kW microwave unit where the product was heated to 135 °C and held at that temperature for 30 s. The pilot-scale test produced a shelf-stable product with no detectable microbial count during a 90-d storage period at room temperature. This is the 1st report of aseptically packaged vegetable puree processed by a continuous flow microwave heating system.     

Anthocyanin content, antioxidant activity, and selected physical properties of flowable purple-fleshed sweetpotato purees

ABSTRACT:  With high levels of polyphenolic compounds, purple-fleshed sweetpotatoes (PFSP) have been utilized as a healthy food commodity and source of natural food colorants in Asia. In the U.S. sweetpotato industry, there are growing interests in exploring these market opportunities for PFSP. A locally grown PFSP cultivar was analyzed for antioxidant properties. The total phenolic content ranged from 313.6 to 1483.7 mg chlorogenic acid equivalent/100 g fresh weight (fw), and anthocyanin contents were between 51.5 and 174.7 mg anthocyanins/100 g fw. The DPPH radical scavenging activities and were 47.0 to 87.4 μmol trolox equivalent (TE)/g fw, and the oxygen radical absorbance capacity (ORAC) values were between 26.4 and 78.2 μmol TE/g fw. Unlike orange-fleshed sweetpotatoes (OFSP), the steamed roots of PFSP formed a thick paste, which required a process modification to produce flowable purees. Rheological testing indicated that adjusting the dry matter of PFSP to 18%-21% produced purees with flow properties similar to the OFSP purees. The PFSP purees had polyphenolic content and antioxidant capacity within ranges reported for various purple-colored fruits and vegetables.     

Antioxidant Capacity and Antioxidant Content in Roots of 4 Sweetpotato Varieties

Abstract: The antioxidant contents (β-carotene, chlorogenic acid, and vitamin C) as well as the antioxidant capacity (ORAC, FRAP, and ABTS) of 4 sweetpotato varieties were measured in this study. The sweetpotato varieties were cultivated under different water regimes and also subjected to thermal processing. The results show that the 2 orange-fleshed varieties (Resisto and W-119) contain significant more β-carotene, chlorogenic acid, and vitamin C than the 2 cream-fleshed varieties (Bosbok and Ndou). Thermal processing decreased the carotenoid and vitamin C content of all the varieties but increased the chlorogenic acid content and antioxidant capacity. Drought stress appears to increase the β-carotene, vitamin C, and chlorogenic acid contents as well as the antioxidant capacity of some of the sweetpotato varieties, especially W-119.     

Processed Tart Cherry Products—Comparative Phytochemical Content,in vitro Antioxidant Capacity and in vitro Anti‐inflammatory Activity

Abstract: Processing of fruits and vegetables affects their phytochemical and nutrient content. Tart cherries are commercially promoted to possess antioxidant and anti‐inflammatory activity. However, processing affects their phytochemical content and may affect their related health benefits. The current study compares the in vitro antioxidant capacity and anti‐inflammatory cyclooxygenase activity of processed tart cherry (Prunus cerasus) products—cherry juice concentrate, individually quick‐frozen cherries, canned cherries, and dried cherries. Cherry products were analyzed for total anthocyanin and proanthocyanidin content and profile. On a per serving basis, total anthocyanins were highest in frozen cherries and total proanthocyanidins were highest in juice concentrate. Total phenolics were highest in juice concentrate. Juice concentrate had the highest oxygen radical absorbance capacity (ORAC) and peroxynitrite radical averting capacity (NORAC). Dried cherries had the highest hydroxyl radical averting capacity (HORAC) and superoxide radical averting capacity (SORAC). Processed tart cherry products compared very favorably to the U.S. Dept. of Agriculture‐reported ORAC of other fresh and processed fruits. Inhibition of in vitro inflammatory COX‐1 activity was greatest in juice concentrate. In summary, all processed tart cherry products possessed antioxidant and anti‐inflammatory activity, but processing differentially affected phytochemical content and in vitro bioactivity. On a per serving basis, juice concentrate was superior to other tart cherry products. Practical Application: Processing of fruits and vegetables affects their chemical and nutrient content and perhaps their related health benefits. Comparative studies are valuable to ascertain the effects of processing on fruit and vegetable chemical content and bioactivity. Here we present tart cherries as a model for this type of detailed comparison.     

中国绿茶传统加工过程中抗氧化物质含量及抗氧化活性的变化

研究中国绿茶传统加工过程不同工艺阶段茶汤总酚、总黄酮、抗坏血酸含量和抗氧化能力的变化。加工成品的总酚含量从鲜叶的119.91mg/g(以干质量计)下降到100.33mg/g,总黄酮含量也有相似的变化趋势,从2.90mg/g下降到2.04mg/g,且这两种成分的降低主要发生在“回潮”阶段。此外,加工过程中茶汤抗坏血酸含量也逐渐下降(从4.17mg/g降至2.95mg/g)。尽管经过剧烈的加工,鲜叶总抗氧化能力(TEAC)仅出现轻微降低,TEAC从(524.94±18.68)μmol/g降至成品中的(487.03±17.97)μmol/g,但总酚和总黄酮与TEAC无线性关系(R2=0.19,R2= 0.01),而DPPH自由基与总酚和总黄酮有较好的线性关系(R2=0.77,R2=0.56)。此外,加工过程中茶叶抗自动氧化能力增强(抑制率从52.45%增加至78.12%)。表明中国绿茶传统加工过程导致成品茶汤主要抗氧化物质含量的减少,但仅导致其抗氧化能力的轻微改变。     

超高压和高温短时杀菌对沙棘汁品质的影响

为了筛选出适合制汁的沙棘品种,对‘中国沙棘’‘圣果一号’‘深秋红’3 种沙棘的理化品质进行比较。结果表明,‘中国沙棘’具有最高的超氧化物歧化酶（superoxidative dismutase,SOD）活力（（1 029.14±77.72）U/g）、总酚含量（（8.37±0.20）mg GAE/g）及抗氧化能力（1,1-二苯基-2-三硝基苯肼自由基清除能力（11.04±0.27）mmol TE/100 g、铁离子还原抗氧化能力（6.06±0.32）mmol TE/100 g）。沙棘汁（经‘中国沙棘’制得,下同）经浓缩后SOD活力提高2.5 倍以上,可作为功能性产品。对超高压（high pressure processing,HPP）（500 MPa/6 min）或高温短时（high-temperature short-time,HTST）（100 ℃/15 s）处理后的沙棘汁品质进行了比较。两种处理都可以使沙棘汁中的菌落总数下降超过3（lg（CFU/mL））,且使霉菌和酵母无法检出。此外,两种处理均提高了沙棘汁中SOD的活性,其中HPP处理组的SOD活性在贮藏期间更高。两种处理均很好地保留了总酚、抗坏血酸含量及抗氧化能力,且这些品质指标在4 ℃冷藏期间同样得到很好的保留。综上,HPP和HTST处理的沙棘汁都是具有高SOD活性和抗氧化能力的产品。     

Processing and Storage Effects on Monomeric Anthocyanins, Percent Polymeric Color, and Antioxidant Capacity of Processed Black Raspberry Products

ABSTRACT:  This study evaluated the effects of processing and 6 mo of storage on total monomeric anthocyanins, percent polymeric color, and antioxidant capacity of black raspberries that were individually quick-frozen (IQF), canned-in-syrup, canned-in-water, pureed, and juiced (clarified and nonclarified). Total monomeric anthocyanins, percent polymeric color, and ORAC_FL were determined 1 d postprocessing and after 1, 3, and 6 mo of storage. Thermal processing resulted in marked losses in total anthocyanins ranging from 37% in puree to 69% to 73% in nonclarified and clarified juices, respectively, but only the juices showed substantial losses (38% to 41%) in ORAC_FL. Storage at 25 °C of all thermally processed products resulted in dramatic losses in total anthocyanins ranging from 49% in canned-in-syrup to 75% in clarified juices. This coincided with marked increases in percent polymeric color values of these products over the 6-mo storage. ORAC_FL values showed little change during storage, indicating that the formation of polymers compensated for the loss of antioxidant capacity due to anthocyanin degradation. Total anthocyanins and ORAC_FL of IQF berries were well retained during long-term storage at –20 °C.     

Analysis of Phenolic Composition of Noble Muscadine (Vitis rotundifolia) by HPLC‐MS and the Relationship to Its Antioxidant Capacity

Abstract: Phenolic compounds and anthocyanins in muscadines have attracted much attention due to their diverse biological activities. With bioassays of antioxidant activities in terms of total phenolic content (TPC), total anthocyanin content (TAC), total procyanidin content (TPA), oxygen radical absorbance capacity (ORAC), and ferric reducing antioxidant power (FRAP) of different parts of the Noble muscadine, the butanol (BuOH) extract of the muscadine skin showed the highest TPC (317.91 ± 1.83 mg GAE/100 g FW), which might be ascribed to its high TAC of 227.06 ± 1.29 mg/100 g fresh weight (FW). The ethyl acetate (EtOAc) extract of the muscadine seed contained the highest TPA (55.30 ± 0.63 mg CE/100 g FW). Correlation analyses demonstrated a significant linear relationship of TPC and TAC compared to their ORAC and FRAP values within the range of R² from 0.9283 to 0.9936, which suggested that phenolics and anthocyanins in the extracts contributed significantly to their antioxidant potential. Nineteen individual phenolics and 5 anthocyanins were identified by HPLC‐MS, which indicated different chemical profiles of anthocyanins and other phenolics in the muscadine extracts. Practical Application: The paper has provided rich information of bioactive phytochemical profiles in different solvent extracts and their correlation with the antioxidant activity in the muscadine that is a very special regional fruit in U.S. Its high content of phenolic compounds demonstrates that muscadine could be beneficial to human health.     

Novel Radiofrequency‐Assisted Thermal Processing Improves the Gelling Properties of Standard Egg White Powder

Effect of radiofrequency (RF)‐assisted thermal processing on quality and functional properties of high‐foaming standard egg white powder (std. EWP, pH approximately 7.0) was investigated and compared with traditional processing (heat treatment in a hot room at 58 °C for at least 14 d). The RF‐assisted thermal treatments were selected to meet the pasteurization requirements and to improve the functional properties of the std. EWP. The treatment conditions were: RF heating to 60, 70, 80, and 90 °C followed by holding in a hot air oven at those temperatures for different periods ranging from 4 h at 90 °C to 72 h at 60 °C. The quality (color and solubility) and functional properties (foaming properties: foaming capacity and foam stability; and gelling properties: water holding capacity and gel‐firmness) of the std. EWP were investigated. RF‐assisted thermal processing did not affect the color and solubility of std. EWP at any of the treatment conditions. In general, the foaming and gelling properties of RF‐assisted thermally processed std. EWP increased with an increase in temperature and treatment duration. The optimal RF‐assisted treatment conditions to produce std. EWP with similar functional properties as the traditionally processed (hot room processed) std. EWP were 90 °C for ≥8 h. These optimal conditions were similar to those for high gel egg white powder (HG‐EWP, pH approximately 9.5). The RF‐assisted thermal pasteurization improved the gelling properties of std. EWP to the levels of HG‐EWP, leading to newer applications of this functionally improved safe product. The RF‐assisted thermal processing allows the processor to produce a HG‐EWP from std. EWP subsequent to processing while simultaneously pasteurizing the product, thus assuring the product safety.     

Microwave‐Assisted Extraction,Chemical Structures,and Chain Conformation of Polysaccharides from a Novel Cordyceps Sinensis Fungus UM01

Cordyceps sinensis is a well‐known tonic food with broad medicinal properties. The aim of the present study was to investigate the optimization of microwave‐assisted extraction (MAE) and characterize chemical structures and chain conformation of polysaccharides from a novel C. sinensis fungus UM01. Ion‐exchange and gel filtration chromatography were used to purify the polysaccharides. The chemical structure of purified polysaccharide was determined through gas chromatography‐mass spectrometry. Moreover, high performance size exclusion chromatography combined with refractive index detector and multiangle laser light scattering were conducted to analyze the molecular weight (M_w) and chain conformation of purified polysaccharide. Based on the orthogonal design L₉, optimal MAE conditions could be obtained through 1300 W of microwave power, with a 5‐min irradiation time at a solid to water ratio of 1:60, generating the highest extraction yield of 6.20%. Subsequently, the polysaccharide UM01‐S1 was purified. The UM01‐S1 is a glucan‐type polysaccharide with a (1→4)‐β‐d ‐glucosyl backbone and branching points located at O‐3 of Glcp with a terminal‐d ‐Glcp. The M_w, radius of gyration (R_g) and hydrodynamic radius (R_h) of UM01‐S1 were determined as 5.442 × 10⁶ Da, 21.8 and 20.2 nm, respectively. Using the polymer solution theory, the exponent (ν) value of the power law function was calculated as 0.38, and the shape factor (ρ = R_g/R_h) was 1.079, indicating that UM01‐S1 has a sphere‐like conformation with a branched structure in an aqueous solution. These results provide fundamental information for the future application of polysaccharides from cultured C. sinensis in health and functional food area.     

Effect of chlorophyll removal and particle size upon the nutritional and technological properties of powdered by‐products from artichoke (Cynara scolymus,L.) industrial canning

In this study, the effect of the particle‐size fractionation (Ø < 0.212 mm and 0.212 mm < Ø < 0.991 mm) and chlorophyll extraction on the nutritional and technological properties of the powdered artichoke ingredient was evaluated. The contents of minerals, protein, fat, carbohydrates and dietary fibre together with the content in bioactive compounds such as inulin and phenolics were determined. Other properties such as water‐ and oil‐holding capacities, water activity and antioxidant capacity were measured. The ingredient with chlorophyll and the lowest particle size presented the highest phenolic content and antioxidant capacity (8.4 mg of vitamin C equivalents per 100 g of dry matter) and water‐ and oil‐holding capacities. The removal of chlorophyll increased the oil‐holding capacity (from 59.7% to 94.6%), which was much higher than in the coarse ingredient (34%), but has a deleterious effect reducing the antioxidant capacity and the inulin content. The ingredients also showed high dietary fibre (22.5–33%), inulin (9–16%) and mineral (7.5–7.8%) contents. Although the ingredient with chlorophyll and smaller particle size had the higher antioxidant capacity, the removal of chlorophyll improved the technological properties to be used as food ingredient without affecting significantly to the nutritional value.     

Antioxidant capacity of methanolic and water extracts prepared from food‐processing by‐products

This study aims to evaluate the antioxidant capacity of mango peel, roselle seed, okara (by‐product of soya milk industry), cocoa shell and pink guava (by‐product of pink guava industry) in comparison to 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid (Trolox). The β‐carotene bleaching, 1,1‐diphenyl‐2‐picrylhydrazyl and reducing power assays were used to determine the antioxidant capacity of selected by‐products by measuring the absorbance at 470, 520 and 700 nm, respectively. The results showed that methanolic extracts of pink guava and cocoa shell exhibited the highest antioxidant activity and free radical scavenging activity compared to other studied samples. Roselle seed water extract exhibited the highest antioxidant activity and free radical scavenging when extracted with water. Pink guava possessed the highest reducing power in methanolic extract at a concentration of 0.16 mg mL^?1. At the same concentration, mango peel exhibited the highest reducing power when extracted with water. The present study shows that pink guava, roselle seed and cocoa shell are potential sources of antioxidant components that can be exploited as food preservative agents or nutraceuticals. Copyright © 2006 Society of Chemical Industry     

Effect of differently processed açai (Euterpe oleracea Mart.) on the retention of phenolics and anthocyanins in chewy candies

This study investigated the effects of processing and storage on the physicochemical properties and retention of antioxidant compounds of no‐added sucrose chewy candies (NASC) incorporated with differently processed açai (frozen pulp, spray‐dried and freeze‐dried powders). NASC containing freeze‐dried açai had the highest softness and recoveries of total phenolic (TP) and total anthocyanin (TA) immediately after production. Colour parameters and antioxidant capacity by ABTS and ORAC assays had no significant differences after 6 months of NASC storage, except for ORAC in NASC containing spray‐dried açai, whereas DPPH^? in all samples significantly increased. Water activity and hardness also increased after storage, whereas TP and TA contents decreased, despite presenting good retentions (approx. 72–78% TP and 84–99% TA). This study suggests that açai has a great potential to be used as a natural pigment and antioxidant source in candy manufacturing, meeting consumption trends towards healthier products.