Sour Odor Research Articles

First report of Geotrichum candidum causing postharvest sour rot on kiwifruits in China.

Kiwifruit (Actinidia spp.) has been extensively cultivated (about 165728 hm2 recorded in 2017) and postharvest rot diseases have caused severe losses to the industry in China. In October 2019, fruit (n=60) of cv. Xuxiang (A. deliciosa) were obtained from a farm (120.62°E, 28.92°N) in Pan'an county, Zhejiang province, China. After the fruit were stored at 24 °C and 70% relative humidity (RH) for 10 days, soft lesions (20 to 45 mm in diameter) with sour odor and white mycelium were observed on ~20% of fruits (Fig. 1a). Irregular lesions were produced on the mesocarp were off-white to pale yellow (Fig. 1b). Small pieces (4×4 mm) from the lesion margins were excised, surface disinfested in 70% ethanol for 1 min and 10% NaOCl for 5 min, washed, dried, plated on PDA and incubated at 25°C for 7 days. A total of seven pure fungal colonies were obtained, and included two isolates of Nigrospora sphaerica (Li et al. 2018) and five unknown isolates. The remaining five isolates produced thin, flat, white to cream and feathery (Fig.1c & d) mycelium. Hyphae were hyaline, septate, dichotomously branched and break into chains of subglobose to cylindrical arthrospores (Fig. 1e, f & g). The dimension of arthrospores varies from 4.11 to 12.55 × 2.54 to 5.84 µm (n=100) (Fig. 1h). To identify these isolates to species, the internal transcribed spacer (ITS), 26S rDNA, translation elongation factor-1 alpha regions (TEF-1α) were amplified and sequenced (Ma et al. 2018). Sequence analysis indicated no differences in 26S rDNA and TEF-1α, but the ITS that placed the isolates into two phylogenetic groups. Isolates gx2-2 and gx3-1 representing group one (gx2-1, gx2-2, and gx5-1) and group two (gx3-1 and gx4-1) respectively, were employed for further studies. Based on BLASTn analysis, ITS sequences for gx2-2 (MT946912) and gx3-1(MT946913) isolates had 100% and 98.40% identity respectively, with G. candidum accessions KY103452 and KY103455. Nevertheless, 26S rDNA sequences (MT981194; MT981195) showed 99.82% identity with G. candidum accessions JN974268 and KF112070. Consistently, the TEF-1α (MT981184; MT981185) had 100% identity with G. candidum accession MT346370. Phylogenetic trees were constructed using the Neighbor-Joining method with a dataset of ITS (Fig. 2a) and 26S rDNA sequences (Fig. 2b), respectively. Based on morphology and phylogenetic analysis, the pathogens gx2-2 and gx3-1 were identified as Geotrichum candidum (De Hoog et al. 1986). To determine pathogenicity, healthy and mature kiwis cv. Xuxiang were surface sterilized. Wounded and unwounded fruits were inoculated with each conidial suspension derived from the two isolates (107 conidia/mL, 30 μL for each fruit) and stored at 24 °C under 90% RH. Control fruit were treated with sterile distilled water. Each treatment consisted of 20 fruit was evaluated daily for 10 days and repeated once. The symptom was mimic the naturally infected fruits (Fig.1i, m & n). The pathogen could develop into inner pericarp after 7 days while cv. Jinyan (A. chinensis) was used as host (Fig. 1k & l). However, control group remained disease-free (Fig. 1j, o & p). The fungus could penetrate into fruit peel and produce spores that were visualized by scanning electron microscope (Fig.1q & r). For both isolates, the incidence of wounded fruit were 100%, and the incidence of unwounded fruit was 80%. The fungi were re-isolated from diseased tissues and re-identified as G. candidum based on morphology and sequences analyses. G. candidum causes sour rot on many hosts and similar symptom have been previously reported in other regions(Pennycook et al.1989; Horita et al. 2016; Ma, et al. 2018; Zhang et al. 2018; Khan et al. 2019; Halfeld-Vieira et al. 2020), but this is the first report of G. candidum on kiwifruit in China.

Investigating the Etiology of Sour Knuckles in Postchilled Beef Carcasses

Development of sourness in beef round muscle cuts, such as knuckles, has been a long-standing issue in the beef industry with little characterization. Therefore, the objective of this study was to investigate and characterize the sour odor associated with beef knuckles using sensory, analytical (gas chromatography-mass spectrometry [GC-MS]), and microbiological approaches. Knuckles (n = 10) with no sour odor (control), a slight sour odor, or severe sour odor were collected during fabrication from a commercial beef processing plant. In addition, the synovial fluid from the femur joint, and the femur surface associated with the collected knuckles, were sponge-sampled. Knuckles were separated into 2 halves, with one half subjected to an odor panel, GC-MS, and microbial analyses on the day of collection (day 0). The remaining half was analyzed for odor and microbial populations following 35 d of vacuum-packaged storage at 0°C ± 2°C (day 35). Odor panelists identified differences (P < 0.05) between control and sour knuckles (slight sour odor and severe sour odor) for all attributes tested (off-odor, oxidation, putrid, and sour notes) regardless of storage day. GC-MS analysis found no statistical difference (P > 0.05) in volatiles between control and severe-sour-odor samples. Microbial analysis (aerobic plate counts and lactic acid bacteria counts) of muscle tissue on day 0 and day 35 of storage revealed no (P > 0.05) differences between the 3 treatment groups. Similarly, no (P > 0.05) differences between the treatment groups were obtained following analysis of synovial fluid and femur surface sponge samples for psychrotrophic anaerobic sporeformer counts. The findings of the study indicated that the souring condition in knuckles exists at identifiable intensities with no volatile acid or microbial population differences; therefore, further investigation is needed to determine the etiology.

First report of sour rot of strawberry caused by Geotrichum candidum in the United States.

Strawberry (Fragaria x ananassa) is an important crop in the U.S., and Florida is the second major producer in the country. In January 2020, an unknown fruit rot was observed in two strawberry fields in Dover (seedling selection) and Plant City (cultivar Florida127), Florida. Disease incidence varied from less than 1% in one field to up to 15% in the second field during some harvests where over-ripe fruit were present. Affected fruit had a water-soaked soft rot with a sour smell, and sometimes with white mycelium on the fruit surface. Direct isolation was performed from symptomatic fruit from each area by touching the surface of a lesion with a sterile needle and streaking the fungus over general isolation medium (Amiri et al. 2018). The fungus was incubated at 25°C and 12-h photoperiod for five days. Four single-spore isolates (20-46 and 20-47 from Plant City; 20-49 and 20-50 from Dover) obtained from different colonies were grown on potato dextrose agar (PDA). Colonies were white to cream, flat, with a powdery surface, and had a characteristic sour odor. Hyphae were hyaline, septate, growing in a dichotomous pattern and often disarticulating into arthroconidia, which were unicellular, spherical to cylindrical, measuring 4.8 to 9.5 × 3.5 to 5.6 µm (n = 50). Based on the morphological characteristics, the fungus was identified as Geotrichum candidum (De Hoog et al. 1986). To confirm the identity of the isolates, the ribosomal internal transcribed spacer (ITS-rDNA) and the translation elongation factor 1-alpha (TEF1-α) gene regions were amplified and sequenced using the primers ITS1/ITS4 (White et al. 1990), and EF1-728F/EF1-1567R (Carbone and Kohn 1999), respectively. Consensus sequences were deposited in the GenBank (accession numbers MT353975 to MT353978 for ITS-rDNA, and MT346367 to MT346370 for TEF1-α). The BLASTn analysis revealed 99% identity with reference sequences of G. candidum for ITS-rDNA (KU373122) and TEF1-α (MK397513). Phylogenetic analysis, including ITS sequences of G. candidum and other spp., obtained from GenBank, was performed using maximum likelihood and Bayesian inference methods, implemented in MEGA-X and MrBayes, respectively. The isolates were grouped within the G. candidum clade. The pathogenicity of the fungus (isolate 20-46) was evaluated in ripe and green strawberry fruit (cultivar Florida127). Non-wounded and superficially wounded (with a sterilized needle) fruit were inoculated with 20 µl of a spore suspension (1 × 107 spore/ml), prepared by washing the surface of a 5-day-old colony on PDA, with sterile deionized water (SDW) plus 0.01% (v/v) Tween 20. Wounded and non-wounded control fruit were treated with SDW. Fruit were maintained in moist containers at 25°C. Each treatment consisted of 12 fruit (three replicates, each containing four fruit) and was evaluated daily for 10 days. Symptoms of sour rot were visible as soon as 48 hr after inoculation, but only on ripe (100% incidence) and green (58% incidence) wounded fruit. Symptoms progressed to an intense water-soaking with the presence of a typical white mycelium on the surface. Control fruit remained symptomless. The fungus was successfully recovered from symptomatic fruit, fulfilling Koch's postulates. Although strawberry fruit rots caused by G. candidum have already been reported in Pakistan and China (Hussain et al. 2016; Ma et al. 2018), this is the first report of this species causing sour rot on strawberry in the U.S. The disease may be a minor problem on damaged or over-ripe fruit, but further studies might be needed to determine its importance, distribution, and potential strategies for control.

Investigating the Etiology of Increased Incidence of Sour Knuckles in Commercial Beef Processing Facilities

ObjectivesCattle weights have increased during the last couple of decades and have not always been accompanied by improvements in facility capabilities and management. Alongside quality issues of color, tenderness, and water holding capacity, issues such as sour muscles and bone taints are now appearing with great frequency in the meat industry. Development of off-flavor/sourness in deep muscles such as knuckles (vastus femoris, vastus lateralis, vastus medialis, and rectus femoris) has been a long-standing issue in the beef industry, however, has not been well characterized. Therefore, the objective of this study was to investigate the cause, and characterize sour odor associated with beef knuckles using microbial, odor panel, and gas chromatography-mass spectrometric (GC–MS) analyses.Materials and MethodsKnuckles (n = 10) identified as having no sour odor (control), slight odor, or severe odor were collected from the fabrication line of a commercial beef processing plant. Sponge samples of synovial fluid and femur surface of the round were also obtained at the time of collection, for determination of anaerobic sporeformer counts. The collected knuckles were transported on ice to the laboratory where they were aseptically separated into two halves, with one half destined for microbial, odor, and GC–MS analyses on the day of collection (Day 0) and the other half for the same analyses after 35 d of vacuum packaged storage at 2°C (Day 35). For microbial analysis, 15 g of tissue was excised from the muscle surface and was analyzed for aerobic plate counts (Petrifilm Aerobic Count plates) and lactic acid bacteria counts (Lactobacilli MRS agar). Samples (5 g) for GC–MS were held at –80°C until analysis. The remainder of the sample was diced and used for trained odor panels. Data were analyzed using the ANOVA function in R (v. 3.5.1.), with a significance level of α = 0.05. Upon finding significant differences (P < 0.05) the means function was used to determine differences between groups.ResultsIrrespective of sourness classification of the knuckles, similar (P > 0.05) anaerobic sporeformer counts were obtained for the synovial fluid and femur surface. Additionally, muscle tissue samples from control, slightly sour and severely sour knuckles had similar (P > 0.05) aerobic plate counts and lactic acid bacteria counts. Odor panelists identified differences (P < 0.05) for all attributes between control and sour knuckles (slight and severe) on Day 0. Similarly, on Day 35, differences (P < 0.05) were observed between control, slightly sour, and severely sour knuckles for all attributes, with severe receiving the highest score for all categories. GC–MS results showed no differences (P > 0.05) between control and sour knuckles for propionic, butyric, isobutyric, and acetonic acid.ConclusionMicrobiological analysis found no differences in culturable organisms between control, slight, and severely sour knuckles on Day 0 or Day 35. However, odor panelists were able to identify differences between control and sour knuckles even after 35 d in vacuum packaging. GC–MS analysis did not indicate a statistical difference in the abundance of volatiles between the treatments, probably due to high variations within treatment groups.

Evaluation of Late-Maturing Peach and Nectarine Fruit Quality by Chemical, Physical, and Sensory Determinations

In this work, both analytical and sensory determinations were carried out to evaluate the quality of yellow (‘Summerset‘, ‘Tardiva 2000‘, ‘Fairtime’, ‘Guglielmina’) and white flesh (‘Daniela’) late-ripening peach and nectarine (‘California’ and ‘Fairlane’) cultivars. Analytical measurements included weight, diameter, soluble solid content, titratable acidity, pH, and peel color. To describe and quantify the peach and nectarine sensory profile, a panel of 10 judges generated 15 descriptors. According to univariate analysis of fruit quality attributes, ‘Fairtime’, ‘Summerset, ‘Daniela’, and ‘California’ produced large and attractive fruits with an extensive red peel color. On the other hand, ‘Guglielmina’, ‘Daniela’, ‘Tardiva 2000’, and ‘Fairlane’ produced superior quality fruit in terms of soluble solids, titratable acidity, sweetness, and flavor. The white flesh peach ‘Daniela’ produced fruits with the best balance between external and internal quality. Cluster analysis on standardized component coordinates from biplot analysis allowed for the identification of two main groups. One group included ‘Daniela’, ‘Guglielmin’, ‘Tardiva 2000’, and ‘Fairlane’, along with attributes that are more indicative of ripe fruit such as soluble solids, sweetness, sugar/acid, juiciness, ground color index, peel color uniformity, flesh color intensity, mealiness, peach odor and flavor, and flower odor and flavor. The other group included ‘Summerset’, ‘Fairtime’, and ‘California’ along with weight, diameter, consistency, flesh firmness, percentage of cover color, bitterness, titratable acidity, sour odor and flavor, and grassy odor and flavor. The dual approach adopted in this study indicates that cultivars with large and attractive fruits are often lacking real eating quality. This poses serious doubts on the real value of exterior appearance for recognizing high-quality peaches and nectarines.

Development of yuja (Citrus junos) beverage based on antioxidant properties and sensory attributes using response surface methodology.

This study aimed to develop a new type of Citrus junos beverage (known as yuja in Korean and yuzu in Japanese) based on a traditional drink preparation method (Galsu). Processing conditions (yuja extract, sugar, and soybean milk) were optimized using response surface methodology (RSM) to develop the beverage. The polynomial models developed by RSM were based on physicochemical characteristics and sensory attributes. Sugar, vitamin C, and total phenolic compound contents, DPPH free radical scavenging activity, sweet odor, yuja flavor, sweet taste, and pungent sensation were used as indices of positive product quality. Beany flavor, astringent taste, beany aftertaste, and astringent aftertaste, were used as indices of negative product quality. Sour odor and sour taste, which are the major characteristics of the traditional yuja beverage, were set in a range to optimize the numerical model. The predicted optimum formulation of yuja beverage (Galsu) as a final product was determined to be 28.4% yuja extract, 36.6% sugar, and 35.0% soybean milk.

Ảnh hưởng của loại khoai lang đến sự lên men, thể tích rượu và chất lượng rượu chưng cất

Sweetpotato tubers with grade 2, (small, broken or scratched) are cheap but are not utilized for food production. Sweetpotato varieties contain various biochemical compounds (water, sugar, starch, protein and lipid) to grow molds and yeasts for winemaking. Therefore, the aim of this study was to investigate effects of four sweetpotato varieties (red, milk, purple and white) on: (i) medium change (Brix and acid) with the fermentation time and (ii) ethanol yield and quality (concentrations of ethanol, acid, aldehyde, methanol and ester; and sensory attributes) of the distilled wine. The results showed that the white sweetpotato roots had the lowest water content (67.57%), and the highest starch content (22.28%) among the four sweetpotatoes. The red sweetpotato contained the highest water content (75.87%) and the milky sweetpotato had the lowest starch content (14.62%). The distilled wine (liquor) would obtain the highest ethanol yield (95.6%), low foreign matter concentrations (aldehyde, methanol, acid and ester) and good sensory values (aroma and taste) if the white sweetpotato was used for winemaking. The liquor had the lowest ethanol yield (91.81%), high concentrations of the foreign matters and sour odor in case of using the milky sweetpotato. The statistical results showed that ethanol yield, ester and acid in the liquors were correlated significantly (p

First Report of Sour Rot Caused by Geotrichum candidum on Mori fructus in China

Mori fructus (Morus alba L., Morus, Moraceae) has been cultivated extensively for a long time in China. The fruit is delicious and beneficial for people’s health. In May 2016, a severe sour rot disease on the postharvest and ripe mulberry fruit was observed in the local fruit market of Chengyang district of Qingdao city (36°18′25.24″N, 120°23′28.17″E), Shandong province, China, which resulted in approximately 50% yield losses of fruits. The initial symptoms of the disease appeared as some small white mildew spots, which spread gradually and covered the whole fruit surface with a thin layer of white mycelium. The infected ripe fruit displayed a water-soaked soft rot with a sour odor. Twelve fungal isolates that showed similar morphological characteristics were isolated from the diseased fruits. Specimens were deposited in the Mycological Herbarium of Qingdao Agricultural University. Colonies plated on potato dextrose agar were white, flat, and nearly powdery. Mycelia were hyaline, septate, with 2.5 to 6.3 μm width and about 5.0 mm/day growth rate at 28°C, which were often extended by dichotomous branching. Arthroconidia, produced from long aerial chains, were achromatous, one-celled, cylindrical (5.0 to 15.0 × 3.5 to 6.3 μm), and germinated from one single end. Morphological characteristics matched the descriptions of Geotrichum candidum (De Hoog et al. 1986). To confirm the identification, genes of the internal transcribed spacer (ITS) using ITS1 and ITS4 primers, 26S rDNA, and the extensive factors (TEF-1α) were amplified. The resulting 295-bp sequence of ITS was deposited in GenBank (accession no. KY486783), which showed 99% similarity with Galactomyces geotrichum (accession no. AJ279445.1) and 98% similarity with G. candidum (accession no. JN974289.1). The resulting 588-bp sequence was obtained after the amplification of the 26S rDNA gene, which showed 99% similarity with G. candidum (GenBank: KY107740 and JN974268). A sequence of 281 bp (accession no. KY486781) was obtained after the amplification of TEF-1α (Ef728M and Tef1RX). It had 99% similarity with the TEF-1α gene (accession no. HF559206.1) of G. geotrichum strain CBS 772.71. Based on morphology and approaches of molecular biology, the pathogen was identified as G. candidum. Pathogenicity assays were confirmed by inoculating fresh mulberry fruit. Forty fruits were surface sterilized; among them, 20 fruits were inoculated with conidial suspension (10⁴ conidia/ml, 50 μL for each fruit), and the rest were treated with the same volume of sterilized distilled water for the control. All treatments were cultivated at 28°C. After 2 days of inoculation, white mildew spots appeared, and they spread quickly 5 days later. All inoculated fruits decayed to be liquid with a fermented smell 15 days later. The disease symptoms were the same as those naturally infected. The control fruit remained symptomless. This pathogen was reisolated from the infected fruits, whereas it was not isolated from the control. Therefore, it confirmed that G. candidum was the causal agent of the disease. G. candidum has been previously reported to cause sour rot of strawberry, loquat, and peach (Alam et al. 2017; Hafeez et al. 2015; Hussain et al. 2016), but this is the first report of G. candidum infecting mulberry fruit in China. This fungus detracted from the quality of the fruit and caused great economic losses.

Understanding the microbial basis of body odor in pre-pubescent children and teenagers

BackgroundEven though human sweat is odorless, bacterial growth and decomposition of specific odor precursors in it is believed to give rise to body odor in humans. While mechanisms of odor generation have been widely studied in adults, little is known for teenagers and pre-pubescent children who have distinct sweat composition from immature apocrine and sebaceous glands, but are arguably more susceptible to the social and psychological impact of malodor.ResultsWe integrated information from whole microbiome analysis of multiple skin sites (underarm, neck, and head) and multiple time points (1 h and 8 h after bath), analyzing 180 samples in total to perform the largest metagenome-wide association study to date on malodor. Significant positive correlations were observed between odor intensity and the relative abundance of Staphylococcus hominis, Staphylococcus epidermidis, and Cutibacterium avidum, as well as negative correlation with Acinetobacter schindleri and Cutibacterium species. Metabolic pathway analysis highlighted the association of isovaleric and acetic acid production (sour odor) from enriched S. epidermidis (teen underarm) and S. hominis (child neck) enzymes and sulfur production from Staphylococcus species (teen underarm) with odor intensity, in good agreement with observed odor characteristics in pre-pubescent children and teenagers. Experiments with cultures on human and artificial sweat confirmed the ability of S. hominis and S. epidermidis to independently produce malodor with distinct odor characteristics.ConclusionsThese results showcase the power of skin metagenomics to study host-microbial co-metabolic interactions, identifying distinct pathways for odor generation from sweat in pre-pubescent children and teenagers and highlighting key enzymatic targets for intervention.

Activity of Mentha piperita L. Ethanol Extract against Acetic Acid Bacteria Asaia spp.

Acetic acid bacteria belonging to the genus Asaia spp. are relatively new microbial contaminants in the beverage industry. These bacteria cause organoleptic changes such as increased turbidity, haziness and sour odor. In addition, they are able to form biofilms on the inner parts of production lines, and finally they can cause secondary contamination of final products. For this reason, new methods using effective and safe preservatives are being developed to improve microbial stability of soft beverages. The aim of the research was to investigate the effects of Mentha piperita L. ethanol extract against Asaia spp. biofilm formation. The bacterial adhesion was evaluated by a plate count method and luminometry, as well as fluorescence microscopy. The polyphenolic profile of the mint extract was determined on the basis of high-performance liquid chromatography (HPLC). The obtained microbiological results indicate bacteriostatic effect of mint extract at 10% (v/v) concentration. The plant extract also reduces the number of adhered bacterial cells on polystyrene surface.

Effects of market type and time of purchase on oxidative status and descriptive off-odors and off-flavors of beef in Vietnam

The objective of the current study was to determine the effects of market type (super market – SM, indoor market – IM, open market – OM) and sampling time (at the opening – T0 and 4 h after the opening – T4) on antioxidant capacity, lipid oxidation, and descriptive sensory attributes of beef in Vietnam. Values of FC and TEAC were greater in OM beef than IM and SM (P < 0.001) and FC value was also greater at T4 than T0 (P = 0.038). The beef from SM had 7% greater TBARS than IM and OM (P = 0.003). Livery odor was less intense in raw beef from OM when compared to SM and IM (P ≤ 0.047). Sour odor in raw beef, and livery flavor in cooked beef was increased from T0 to T4 (P ≤ 0.035). Principal component analysis of descriptive sensory attributes indicated that FC and TEAC could predict partial livery flavor in cooked beef, but not off-odors in raw beef.

Shelf life assessment of industrial durum wheat bread as a function of packaging system.

This study compared the effect of different packaging systems on industrial durum wheat bread shelf-life, with regard to thermoformed packaging (TF) and flow-packaging (FP). Two TFs having different thickness and one FP were compared by assessing physico-chemical and sensorial properties and volatile compounds of sliced bread during 90days of storage. Texture, aw and bread moisture varied according to a first-order kinetic model, with FP samples ageing faster than TFs. Sensorial features such as consistency, stale odor, and sour odor, increased their intensity during storage. Furans decreased, whereas hexanal increased. The Principal Component Analysis of the whole dataset pointed out that the TF system at reduced thickness could be adopted up to 60days, without compromising the standard commercial life of industrial bread and allowing to save packaging material. The FP system would allow further saving, but it should be preferred when the expected product turnover is within 30days.

문어 배추김치에서 분리한 Leuconostoc mesenteroides SK-1을 이용한 수산물김치의 제조 및 발효 특성

This study was carried out to investigate the effectiveness of Leuconostoc mesenteroides isolated from octopus baechu kimchi as a potential starter for seafood kimchi. L. mesenteroides is lactic acid bacterium currently used as a starter for kimchi production. We selected the most effective L. mesenteroides strain from the 7 strains isolated from octopus baechu kimchi and, based on biochemical properties and 16S rRNA sequencing, identified the selected strain as L. mesenteroides SK-1. The SK-1 strain exhibited acid-tolerance, good survival capacity, and excellent dextran productivity. We investigated the effects the SK-1 of starter on seafood kimchi fermentation. Octopus baechu kimchi was fermented with L. mesenteroides SK-1 at 4˚C for 35 d. The decrease in pH and increase in acidity in octopus baechu kimchi fermented with the SK-1 starter occurred more quickly than that in the control kimchi indicating that. Octopus baechu kimchi with SK-1 starter has a relatively slow rate of increase in lactic acid production. As a result, octopus baechu kimchi prepared with L. mesenteroides SK-1 can be maintained at a suitable ripening degree over an extended period of time compared to that of the control kimchi, Moreover, the octopus baechu kimchi started with L. mesenteroides SK-1 has excellent sensory properties, including a refreshing taste, and a weak sour odor.

Identification and quantification of nuisance odors at a trash transfer station

The objective of this study was to evaluate the effectiveness of a modified Odor Profile Method (OPM) at a trash transfer station (TTS). An updated Landfill Odor Wheel was used to define odor character and distinguish among odor sources. The Flavor Profile Analysis (FPA) intensity scale was used to rank the relative intensity of the various odor characters defined by the odor wheel and to understand how each odor profile changed off site. Finally, the odor wheel was used to select the appropriate chemical analysis to identify the odorants causing the odors identified by the human panelists. The OPM was demonstrated as an effective tool for characterizing and distinguishing odor sources at a TTS. Municipal solid waste (MSW) odors were characterized as rancid, sulfur, and fragrant; rancid odors were dominant in the odor profile on-site, while sulfur odors dominated off-site. Targeted chemical analysis was used to identify odorants potentially responsible for odors at the site. Methyl mercaptan (rotten vegetable) and hydrogen sulfide (rotten egg) were identified as the odorants most likely to be responsible for the sulfur odors at the site. Acetaldehyde (sweet, fruity), acetic acid (vinegar), and butyric acid (rancid) were identified as the odorants mostly likely to be causing the rancid and sour odors. Terpenes/pine odors were observed near the greenwaste pile. Results confirm that the OPM, together with properly selected chemical analyses, can be a useful tool for identifying and quantifying the sources of odors.

Effect of bacteriocin-producing Pediococcus acidilactici K10 on beer fermentation

Beer is generally considered to be a beverage that has high microbiological stability. However, some undesirable lactic acid bacteria (LAB) can grow in beer and consequently spoil this beverage. In this study, bacteriocin-producing Pediococcus acidilactici K10 was used as a means of bio-acidifying the mash and reducing the spoilage LAB content of the beer. The K10 strain had antimicrobial activity against two beer spoilage LAB strains in wort and did not grow in a beer environment. The K10 strain was inoculated before the mashing step. The effect of K10 as a starter culture was investigated and compared with a control. As a result, filtration time was shortened by 17 min, alcohol content was increased by 137%, foam stability was increased by 156%, bitterness was increased by two bitterness units and there was a significant difference (p < 0.05) in aromatic and sour odour. The feasibility of using bacteriocin-producing LAB strain in beer brewing is envisaged. Copyright © 2016 The Institute of Brewing & Distilling

Storage of fresh-cut swede and turnip: Effect of temperature, including sub-zero temperature, and packaging material on sensory attributes, sugars and glucosinolates

Freezing point of fresh-cut swede (Brassica napus L. var. napobrassica Rchb.) and turnip (Brassica rapa L. ssp. rapifera Metzg.) dice was measured by the cooling curve method, and mean equilibrium freezing points were found to be −2.67 and −1.97°C, respectively. This indicates that storage of fresh-cut swede and turnip at temperatures below 0°C is possible. Fresh-cut swede and turnip were packed in pouches made of biaxially oriented polypropylene film, and a film based on polylactic acid, and stored for 10 d at −2, 0, 5 and 10°C. One sample of each vegetable was stored at −2°C for 5 d, followed by 5 d of storage at 5°C. Differences in sensory quality between storage at −2°C and 0°C were found in appearance attributes only. Both swede and turnip had higher evenness of colour at −2°C than at 0°C. Storage at −2°C vs. 0°C gave lower whiteness for swede but higher for turnip, and lower intensity of hue for turnip only. Increased storage temperature from 0°C to 5 or 10°C did not change appearance in swede, but in turnip hue and colour intensity increased, and colour evenness and whiteness decreased. Differences in odour, taste and flavour during storage at 5 or 10°C vs. 0°C were prominent for turnip: decreased sour odour and flavour, green odour and flavour, sulphurous odour and sweet taste, and increased muddy odour and cloying odour and flavour for 5°C or 10°C. For swede, higher storage temperature gave only increased intensity of sulphurous odour and pungent odour. Texture changed for turnip only with decreased juiciness with increased temperature. The lowest temperature (−2°C) gave the highest sucrose content in both swede and turnip, the highest total sugar content in turnip and the lowest glucose content in swede. Higher storage temperature resulted in higher content of total indolic glucosinolates in both fresh-cut swede and turnip, but a lower content of total aliphatic glucosinolates in turnip only. Increased contents with increased storage temperature were found for glucobrassicin and 4-methoxyglucobrassicin in both vegetables, and decreased contents for glucobrassicanapin and gluconapin in turnip and glucoalyssin in swede. Storage in polylactic acid film resulted in higher weight loss than the biaxially oriented polypropylene film in both vegetables.

Vida útil de carne fresca de res envasada al vacío a 0°C y +4°C

El objetivo de este trabajo fue determinar la vida útil de cortes cárnicos envasados al vacío y almacenados a 0°C y 4°C. Se evaluaron parámetros fisicoquímicos (pH, porcentaje de Drip, rancidez por Kreiss), aspecto del corte (estado del envase, color del corte, grasa, olor); y aspectos microbiológicos (recuentos en placa de bacterias aerobias mesófilas, enterobacterias, Escherichia coli, coliformes totales, bacterias ácido lácticas) en cortes de bife y picaña durante 5 meses.En los cortes almacenados a 4°C se observaron alteraciones fisicoquímicas y de aspecto en el tercer mes (pH &lt;5.4, perdida de vacío y presencia de olores ácidos); mientras que a 0°C no se percibieron alteraciones hasta el quinto mes. Por otro lado, no se observó crecimiento significativo para E.coli ni coliformes totales durante el periodo en estudio.El almacenamiento de cortes envasados al vacío y mantenidos a 0°C contribuye a la calidad del producto, y mantiene sus características fisicoquímicas y sensoriales en condiciones comercialmente aceptables durante cuatro meses, permitiendo su transporte hasta destinos distantes.Producción Agropecuaria y Desarrollo Sostenible, Vol. 4, 2015: 27-45

Combined Effects of Mugwort Herb and Vitamin C on Shelf-Life of Vacuum-Packed Seasoned Pork.

This study was performed to investigate the possibility of the addition of mugwort herb extract (MH) and vitamin C (VC) alone (0.05%) and in combination (0.05% each) on shelf-life of seasoned pork. The combination of VC+MH demonstrated a significant reduction in thiobarbituric acid reactive substances, and volatile basic nitrogen in seasoned pork. Also, the pH values, total lactic acid concentration, lactic acid bacteria count, and the sensory properties (discoloration, flavor, and overall acceptability) of seasoned pork were not significantly affected by adding MH and/or VC. All seasoned pork were rejected by sensory panel when LAB count reached levels of 5-6 Log CFU/g, TLA concentration has been above a level of 3.6-3.9 mg lactic acid/g, and pH values ranged from 5.31-5.51 (15 d). Therefore, the findings showed that spoilage of seasoned pork does not appear to be the result of lipid oxidation, but is caused by lactic acid producing bacteria which result in sour odor.

차량 내 미생물에 의해 생성되는 악취유발 화학물질의 분석

It was confirmed that malodor connected with an air-conditioner in an automobile is caused by microbial volatile organic compounds (MVOCs) produced by microorganisms getting into an air-conditioner when it is operating. Chemicals such as hydrogen sulfide, dimethyl sulfide, nbutyric acid, n-valeric acid, iso-valeric acid, n-octanol and toluene were detected above the odor threshold inside the automobile. The characteristics of a funky odor in the air blown into the automobile were due to detected sulfur compounds (hydrogen sulfide and dimethyl sulfide). Dimethyl sulfide was produced by microorganisms such as Aspergillus versicolor, Methylobacterium aquaticum, Herbaspirillum sp. and Acidovorax sp. In addition, the characteristics of a sour odor in the air blown into the automobile were due to detected organic acids (n-butyric acid, n-valeric acid and iso-valeric acid). N-valeric acid and iso-valeric acid were generated from Aspergillus versicolor, while iso-valeric acid was produced by Methylobacterium aquaticum. In addition, the odor intensity of the air blown into the automobile was affected by the concentration of detected sulfur compounds and organic acids. On the other hand, it is estimated that chemicals such as hydrogen sulfide, n-octanol and n-butyric acid detected in the air blown into the automobile were produced by non-identified species of microorganisms.

Diaporthe ambigua Associated with Post-Harvest Fruit Rot of Kiwifruit in Chile.

Kiwifruit is an important, expanding commercial crop in Chile. Several fungi have been reported to be associated with post-harvest rots of kiwifruit worldwide (2). During 2011 and 2012, kiwifruit produced in the VI and VII regions of Chile, showing symptoms of inner rot, were investigated with the aim of identifying the disease agent. The affected fruits had brown pubescent skin at the stem end that became soft and lighter in color than the adjacent firm healthy tissues. A watery exudate and white to pale grayish mycelial mats frequently developed at the stem end of the fruit, causing a water-drop stain down the sides on the dry brown healthy skin. The underlying tissue accessed by peeling off the skin was usually water soaked, soft, and lighter green than the healthy tissue. A fermented sour odor occurred frequently on severely decayed fruits. After incubation at 25°C over 7 days on potato dextrose agar (PDA), white to grayish, pale aerial mycelial mats were recovered from fragments of symptomatic kiwifruit superficially disinfected with 95% ethanol. After 2 weeks, black, spherical pycnidia developed, bearing hyaline, ellipsoidal, biguttulate conidia (5.4 to 12.6 × 2.1 to 4.7 μm). After 3 weeks, abundant perithecia embedded in a distinct, black, elevated stroma developed. Perithecia were black, globose, 200 to 500 μm in diameter with necks sinuous, filiform, 550 to 840 × 50 to 95 μm. Clavate, sessile asci, 30.9 to 50.2 × 6.6 to 12.5 μm contained ascospores biseriate, hyaline, smooth, fusoid-ellipsoid, widest just above the septum, tapering towards both ends, medianly septate, constricted at the septum at maturity, with 1 to 2 guttules per cell ascospores, 5.9 to 9.7 × 2.5 to 4.3 μm. All colonies obtained from kiwifruit displayed the same morphological traits and were consistent with those of a Diaporthe sp. (1). The internal transcribed spacer (ITS) region was sequenced using ITS1/ITS4 primers (4). Analysis of ITS region of kiwifruit isolates Damb_12 and Damb_16 (GenBank Accession Nos. KC294545 and KC294544, respectively) revealed 100% nucleotide identity to Diaporthe ambigua (HM575420, HM575419, DQ286274, DQ286270, and DQ286271). Six millimeter plugs from fungal colonies growing on PDA at 25°C for 7 days were used to inoculate 15 healthy untreated, ripe 'Hayward' kiwifruits. Control fruits were inoculated with agar plugs. Inoculated fruits were incubated at 25°C and 80% relative humidity. After 7 days, white to pale grayish mycelial mats developed only on the inoculated fruits, releasing a water drop stain. The underlying tissue was lighter green and water soaked. D. ambigua was reisolated only from the inoculated fruits. D. actinidiae has been previously reported on kiwifruit canes in Chile (3); however, to our knowledge, this is the first report on the occurrence of D. ambigua (Phomopsis ambigua) on kiwifruit in Chile. The fungal isolates (no. 1 to 21) have been deposited in the Laboratorio de Fitopatología Frutal y Molecular, Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas de la Universidad de Chile.