A Protocol for Comparing Dry and Wet EEG Electrodes During Sleep.

BACKGROUND: Sleep is commonly assessed by recording the electroencephalogram (EEG) of the sleeping brain. As sleep assessments in a lab environment are cumbersome for both the participant and researcher, it would be highly desirable to record sleep EEG with a user-friendly and mobile device. Dry electrodes that are reusable, low-cost, and easy to apply would be an essential component of such a device. In this study, we developed a testing protocol to investigate the performance of novel flat-type dry electrodes for sleep EEG recordings in free-living conditions. METHODS: Overnight sleep EEG, electrooculogram and electromyogram of four young and healthy participants were recorded at home. Two identical ambulatory recording devices, one using novel flat-type dry electrodes, the other using self-adhesive pre-gelled electrodes, simultaneously recorded sleep EEG. Between both electrode types, we then compared the signal quality, the incidence of artifacts, the sensitivity, specificity and inter-scoring reliability (Cohen's kappa) of sleep staging, as well as the agreement of important characteristics of sleep-specific EEG microstructure features, such as slow waves (0.5-4 Hz) and sleep spindles (10-16 Hz). RESULTS: Our testing protocol comprehensively compared the two electrode types on a macro- and microstructure level of sleep. The dry and pre-gelled electrodes both had comparable signal quality and sleep staging was feasible with both electrodes. Also, slow-wave and spindle characteristics were similar. However, sweat artifacts were more prevalent in the flat-type dry electrodes. CONCLUSION: With a reliable testing protocol, the performance of dry electrodes can be compared to reference technologies and objectively assessed also in free-living conditions.

Use of alternative curing salts for processing salamis.

OBJECTIVE: This study was performed to determine effects of different curing salts on the quality of salamis and to assess feasibility of using NaCl-alternative salts. METHODS: Various types of curing salts (KCl or MgCl2) as well as NaCl (sun-dried or refined) were incorporated for processing of salamis. The proximate composition, fatty acids, nucleotide-related compounds, and free amino acids of the salamis were analyzed during 40 days of ripening. RESULTS: The substitution of NaCl by KCl caused higher fat and ash content, but lower moisture content of the salami after 20 days of ripening (p<0.05). Compared with the sun-dried NaCl, use of KCl in salami also led to greater inosine 5'-monophosphate whereas refined NaCl had more inosine (p<0.05). KCl-added salami also had a higher C12:0, C17:1, and C20:0 than other types of salami (p<0.05). MgCl2-added salami had higher content of free amino acids compared to the other salamis (p<0.05). CONCLUSION: Alternative curing salts such as KCl and MgCl2 could substitute NaCl in consideration of quality factor of a fermented meat product. Especially replacement of NaCl with KCl will be a suitable strategy for developing relatively low sodium salami products without compromising product quality.

Noncontact Sleep Study by Multi-Modal Sensor Fusion.

Polysomnography (PSG) is considered as the gold standard for determining sleep stages, but due to the obtrusiveness of its sensor attachments, sleep stage classification algorithms using noninvasive sensors have been developed throughout the years. However, the previous studies have not yet been proven reliable. In addition, most of the products are designed for healthy customers rather than for patients with sleep disorder. We present a novel approach to classify sleep stages via low cost and noncontact multi-modal sensor fusion, which extracts sleep-related vital signals from radar signals and a sound-based context-awareness technique. This work is uniquely designed based on the PSG data of sleep disorder patients, which were received and certified by professionals at Hanyang University Hospital. The proposed algorithm further incorporates medical/statistical knowledge to determine personal-adjusted thresholds and devise post-processing. The efficiency of the proposed algorithm is highlighted by contrasting sleep stage classification performance between single sensor and sensor-fusion algorithms. To validate the possibility of commercializing this work, the classification results of this algorithm were compared with the commercialized sleep monitoring device, ResMed S+. The proposed algorithm was investigated with random patients following PSG examination, and results show a promising novel approach for determining sleep stages in a low cost and unobtrusive manner.

Effect of Fat Level and the Ripening Time on Quality Traits of Fermented Sausages.

The objective of this study was to investigate the effect of the fat reduction on the physicochemical and microbiological characteristics of fermented sausages during ripening and drying. Low fat fermented sausages were produced with different fat levels (30%, 20%, 10%, and 5%) under ripening conditions and fermented process. Samples from each treatment were taken for physicochemical and microbiological analyses on the 0, 1, 2, 3, 4, 5, 7, 10, 14, and 21st day of ripening. In proximate analysis, the fat reduction in sausages produced an increase in moisture, protein and ash contents during ripening and drying (p<0.05). The weight losses were significantly higher in high fat formulations during the first 4 days, whereas those were higher in low fat ones after 10 days of storage (p<0.05). Fat reduction was responsible for an increase in shear force values after 3 days of storage. The volatile basic nitrogen (VBN) value of the low fat samples was significantly higher (p<0.05). Low fat sausages reduced the extent of lipid oxidation. The lower fat level produced redder sausages. Total plate bacteria and Pseudomonas counts of sausages showed no significant differences. Production of low fat sausages resulted in the physicochemical and microbiological attributes equal to or better than the high fat sausages without negative effects, except only a higher VBN and weight loss.

Quality Characteristics of Dry-cured Ham Made from Two Different Three-way Crossbred Pigs.

This study was conducted to compare the physicochemical traits of dry-cured hams made from two different three-way crossbred pigs: Yorkshire×Landrace×Duroc (YLD) and Yorkshire×Berkshire×Duroc (YBD). Animals were slaughtered at a live weight of 110 to 120 kg and cooled at 0°C for 24 h in a chilling room, the ham portion of the carcasses were cut and processed by dry-curing for physico-chemical analyses. While the moisture and crude protein contents of dry-cured ham were higher in YLD than in YBD, crude fat and ash content were higher in YBD (p<0.05). The salt contents of ham from YBD were higher than those from YLD (p<0.05). YBD ham samples showed a higher L* and b* values than those from YLD, while YBD ham showed lower a* value (p<0.05). Thiobarbituric acid reactive substances (TBARS) and volatile basic nitrogen (VBN) values of YLD hams were lower than those of YBD samples (p<0.05). Hardness, gumminess, chewiness, and shear force values of YBD ham were higher than those of YLD sample (p<0.05). Saltiness was significantly higher in YBD ham than in YLD samples (p<0.05). YLD ham displayed a superior quality than YBD. Considering the meat quality parameters of two-way crossbred ham, YLD hams could be more suitable for the production of dry-cured products.

Physicochemical traits of Holstein loin and top round veal from two slaughter age groups.

The objective of this study was to investigate the physicochemical and microbial quality of loin (m. longissimus dorsi) and top round (m. Semimembranosus) in Holstein veal produced from two slaughter age groups (5 and 8 months of age). A total of 20 Holstein calves were randomly selected from a local cattle farm. The slaughtered cold carcasses were vacuum-packaged. The samples were analyzed for proximate composition and physicochemical analyses and stored for 1, 7, 10, 20 and 30 days for microbiological analyses. Fat and protein contents of loin for the 8 month group were higher than those for the 5 month groups (p < 0.05). For both loin and top round muscles, the pH, cooking loss and the shear force values for the 5 month group was higher than those for the 8 month group (p < 0.05). On the other hands, the water-holding capacity (WHC) for the 8 month group was higher than those for the 5 month group (p < 0.05). In terms of meat color, CIE L* (lightness) for both muscle were higher in the 5 month group than in the 8 month groups. On the other hands, a* (redness) were higher in the 8 month group than in the 5 month groups (p < 0.05). Total aerobic counts in all samples remained up to 30 days at values less than 7 log CFU/g. However, there was no significant difference for both muscles between the two age groups. The results indicate that Holstein muscles from the 8 month group had desirable quality properties than those from the 5 month group.

Effect of GdL Addition on Physico-chemical Properties of Fermented Sausages during Ripening.

This study investigated the effects of glucono-δ-lactone (GdL) addition on physicochemical and microbiological characteristics of fermented sausages during ripening and drying. Five batches of sausages were produced under ripening conditions: without GdL and with 0, 0.1, 0.25, 0.5 and 0.75% of GdL addition. Samples from each treatment were taken for physicochemical and microbiological analyses on the 0, 1, 3, 5, 7, 10, 15, 20 and 25th day of ripening. Chemical analysis showed a significant decrease in moisture content of sausages with increasing amounts of GdL added (p<0.05). The moisture contents decreased, whereas the fat, protein and ash contents increased throughout ripening (p<0.05). Increasing levels of GdL caused a decrease in the pH values (p<0.05), which can have an inhibitory effect against microflora. Water holding capacity content of samples decreased with increasing GdL concentration (p<0.05). The shear force values of fermented sausages showed the highest in T4 (p<0.05). During ripening, the shear force values of sausages were increased on the 25th day compared to day 0 (p<0.05). The higher GdL level produced lighter and more yellow sausages. The addition of 0.75% GdL was effective in controlling bacteria counts. Addition of GdL in sausages resulted in the physicochemical and microbiological attributes equal to or better than no addition of GdL without any harmful effect.

Effect of Quality Grade and Storage Time on the Palatability, Physicochemical and Microbial Quality of Hanwoo Striploin Beef.

The effects of quality grade and storage time on physicochemical, sensory properties and microbial population of Hanwoo striploin beef were investigated. After a total of 30 Hanwoo beef were slaughtered, the cold carcasses were graded by official meat grader at 24 h postmortem. The carcasses were categorized into five groups (quality grade 1++, 1+, 1, 2, and 3) and were vacuum-packaged and stored. The samples were kept for 1, 4, 6, 8, 11, 13, 15, 18, 20, 22 and 25 d for analyses. As the quality grade was increased, moisture, protein and ash contents decreased (p<0.05). Higher quality grade corresponded with higher fat contents. The shear force values decreased with increasing quality grade and showed decreases sharply during the first 4 d (p<0.05). pH, water holding capacity, cooking loss, and volatile basic nitrogen for grade 1++ groups were lower than for grade 3 (p<0.05). CIE L* and b* values increased as increased quality grade (p<0.05). Meat color decreased until 13 d and fluctuated after 15 d of storage (p<0.05). Regarding the sensory scores, higher quality grade corresponded with higher juiciness, tenderness, flavor, fatty and palatability scores (p<0.05). Generally, increased storage time for 15 d improved sensory scores attributes. Results indicate that a high quality grade could positively influence physicochemical and sensory properties.

Meat Quality of Loin and Top Round Muscles from the Hanwoo and Holstein Veal Calves.

This study was conducted to compare the meat qualities of loin (m. longissimus dorsi) and top round (m. semimembranosus) from Hanwoo and Holstein veal. Ten Hanwoo and Holstein calves were randomly selected from a local cattle farm and raised. They were slaughtered when they were 8 mon old and weighed. Weight and percentage in primal cuts and slaughter performance of Hanwoo and Holstein veal calves are obtained. Immediately after weighting, slices of loin and top round muscles were sampled. After vacuum packaging, the samples were subjected to proximate composition, physicochemical and microbiological analyses. Dressing weight and percentage were heavier and greater (p<0.05) in the Holstein than in the Hanwoo. Water contents of the top round muscle was higher in the Holstein than in the Hanwoo (p<0.05). Water-holding capacity, protein content and CIE L* (lightness) of both muscles were higher in the Holstein than in the Hanwoo veal, whereas fat content, pH, cooking loss, a* (redness), and b* (yellowness) were higher in the Hanwoo than in the Holstein veal (p<0.05). Thiobarbituric acid and volatile basic nitrogen values of both the muscles were lower in the Hanwoo than in the Holstein veal during the first 10 d of storage (p<0.05).