Tenderizing, Ageing, and Thawing Effects on Sensory, Chemical, and Physical Properties of Beef Steaks

The effects of electrical stimulation, tender stretching, ageing, freezing and thawing on beef palatability were assessed by a trained sensory panel and by several objective methods. The overall palatability of both longissimus dorsi (strip loin) and semimembranosus (topside) steaks improved with ageing, irrespective of tenderizing method, but there appeared to be little advantage in extending ageing beyond 10 days. Tender stretched longissimus dorsi steaks were marginally preferred by the taste panel to electrically stimulated steaks subjected to the same ageing. Unfrozen steaks were preferable to frozen and thawed steaks with respect to juiciness, flavor and tenderness. Thawing method had little effect on steak palatability.     

Influence of cosmetics on emotional, autonomous, endocrinological, and immune reactions

Recent findings indicate that cosmetics increase positive valence of emotions and thereby influence the autonomous nerve system. Other studies showed the effects of emotions on the endocrinological and the immune system. Based on this preliminary conclusion, the aim of the present study was to prove whether cosmetics are able to decrease the level of the stress hormone cortisol and strengthen the immune system. Four slides of made up or unvarnished women each, integrated in another 16 slides each of equivalent valence and arousal, were presented to 60 women. During stimulus presentation, subjective (valence), autonomous (heart rate), endocrinological (salivary cortisol) as well as immunological reactions [secretory immunoglobulin A (sIgA)] were recorded. As expected subjective ratings concerning the slides of made up women reported more positive valence than those concerning unvarnished women. Furthermore, heart rate decreased under presentation of made up women, which indicates the positive influence of these slides on the autonomous nerve system. Furthermore, in half of the volunteers a decrease of cortisol and an increase of sIgA level while presenting the made up women was measurable in contrast to the presentation of unvarnished women. Maybe this is due to a short presentation time and the endocrinological as well as the immune system can be hardly influenced that quick. Another explanation could be that the volunteers were in part so called psychophysiological non-responders who show no reaction to emotional stimuli in the endocrinological and the immune system. It has to be considered that only the influence of visual stimuli and not the influence of social care (e.g. positive statements of other, etc.), which is normally connected with the use of cosmetics, was assessed, so that these delineated positive results show the lower limit of cosmetic effects.     

Effects of shade and sprinklers on performance, behavior, physiology, and the environment of heifers

The objective was to measure effects of cooling technique (shade vs. water sprinklers) on performance, behavior, physiology, and the environmental effect of 40 Holstein heifers housed in drylot corrals during the hot summer months. The experiment was a replicated crossover design with four 21-d periods and 2 treatments: 1) shades installed in the front half of the pen or 2) sprinklers, which applied water to the pen surface at 2-h intervals from 1100 to 1900 h. Animal performance measures were dry matter intake, average daily gain, and feed efficiency (gain:feed). Behavioral measures, elimination patterns, and corral spatial distribution were measured in 5-min scan frequencies over four 24-h periods. Physiological measures were rectal temperature, respiration rate, urinary urea N, and blood urea N. Environmental measures were corral soil surface temperature and moisture, particulate matter, and surface NH₃ volatilization; meteorological measures were also collected. Shaded compared with sprinkled heifers had increased dry matter intake (3.4%), increased average daily gain (14%), and increased feed efficiency (11%). Heifers in shaded vs. sprinkler treatments had decreased respiration rates (13%). Behavioral differences between the treatments varied by time of day. Heifers spent most time in either the shaded or sprinkled areas of their corrals (65.9 and 64.2%, respectively). Elimination behavior occurred predominantly at the front of the corral in close proximity to the feed bunks and additionally at the water trough in sprinkled corrals. Sprinkler treatment had a 31.7% greater average corral surface moisture than the shaded treatment. Corral surface temperature varied based on areas of surface moisture, shade location, and elimination concentration within the corral. Sprinkled corrals had less particulate matter emissions than shaded (25%), but NH₃ emissions were 46% greater in sprinkler vs. shaded treatment. Overall, the use of shade in heifer corrals improved heifer performance and physiological measures, but sprinkler treatment had less NH₃ emissions from corral surfaces under heat stress conditions. Both cooling techniques affected spatial distribution and behaviors of the heifers, which affected pen usage and surface characteristics.     

Drying, Packaging, and Storage Effects on Quality of Basil, Marjoram and Wild Marjoram

Sorption isotherms, color and sensory qualities of basil (Ocimum basilicum L.) and marjoram (Origanum majorana L.) and sensory qualities of wild marjoram (Origanum vulgare L.) were used to determine effects of packaging, storage temperature and time on air-dried and freeze-dried herbs. Sorption isotherms showed herbs dried with different methods exhibited different sorption capacities. Both odor and taste of freeze-dried basil and the freeze-dried and air-dried marjorams were very sensitive to storage conditions. Processing and storage conditions had only moderate effects on flavor of wild marjoram. The study demonstrated that quality of dried basil, marjoram and wild marjoram could be maintained for 2 yr in air-tight packages at room temperature.     

Effect of fecal contamination and cross-contamination on numbers of coliform, Escherichia coli, Campylobacter, and Salmonella on immersion-chilled broiler carcasses

The effect of prechill fecal contamination on numbers of bacteria on immersion-chilled carcasses was tested in each of three replicate trials. For each trial, 16 eviscerated broiler carcasses were split into 32 halves and assigned to one of two groups. Cecal contents (0.1 g inoculated with Campylobacter and nalidixic acid-resistant Salmonella) were applied to each of eight halves in one group (direct contamination) that were placed into one paddle chiller (contaminated), whereas the other paired halves were placed into another chiller (control). From the second group of eight split birds, one of each paired half was placed in the contaminated chiller (to determine cross-contamination) and the other half was placed in the control chiller. Postchill carcass halves were sampled by a 1-min rinse in sterile water, which was collected and cultured. Bacterial counts were reported as log CFU per milliliter of rinsate. There were no significant statistical differences (paired t test, P < 0.05) from direct contamination for coliforms (mean 3.0 log CFU) and Escherichia coli (mean 2.7 log CFU), although Campylobacter numbers significantly increased from control values because of direct contamination (1.5 versus 2.1 log CFU), and the incidence increased from 79 to 100%. There was no significant effect of cross-contamination on coliform (mean 2.9 log CFU) or E. coli (mean 2.6 log CFU) numbers. Nevertheless, Campylobacter levels were significantly higher after exposure to cross-contamination (1.6 versus 2.0 log CFU), and the incidence of this bacterium increased from 75 to 100%. Salmonella-positive halves increased from 0 to 42% postchill because of direct contamination and from 0 to 25% as a result of cross-contamination after chilling. Water samples and surface swabs taken postchill from the contaminated chiller were higher for Campylobacter than those taken from the control chiller. Immersion chilling equilibrated bacterial numbers between contaminated and control halves subjected to either direct contamination or cross-contamination for coliforms and E. coli. Campylobacter numbers, Campylobacter incidence, and Salmonella incidence increased because of both direct contamination and cross-contamination in the chiller. Postchill E. coli numbers did not indicate which carcass halves were contaminated with feces before chilling.     

Effects of florfenicol, chloramphenicol, and thiamphenicol on phagocytosis, chemiluminescence, and morphology of bovine polymorphonuclear neutrophil leukocytes

Florfenicol, chloramphenicol, and thiamphenicol were tested in vitro to determine their potential toxic effects on bovine neutrophils. Antibiotics were tested at 4000, 2000, and 10 micrograms/ml of incubation mixture. Percentage phagocytosis was determined by incubations with neutrophils isolated from milk of five cows and 32P-labeled Staphylococcus aureus and 5% skim milk. The effect of 4000 micrograms of each antibiotic on chemiluminescence was determined on neutrophils isolated from mammary secretions of three nulliparous heifers. Morphological evaluation by transmission and scanning electron microscopy was performed on neutrophils isolated from two heifers at antibiotic concentrations of 4000 and 10 micrograms/ml. Chloramphenicol depressed phagocytosis at the high and medium doses and blocked chemiluminescence activity at the high dose. No effects were observed for florfenicol and thiamphenicol. Transmission electron microscopic examination showed that at the high concentration of drugs, 99, 99, 97, and 76% of the neutrophils treated with florfenicol, chloramphenicol, thiamphenicol, and dimethyl sulfoxide were abnormal. Examination by scanning electron microscopy showed that the percentage of neutrophils without pseudopodia averaged 67, 94, 32, and 16%, respectively. Results indicated that neither florfenicol nor thiamphenicol altered neutrophil function, but they did alter neutrophil morphology, although to a lesser extent than did chloramphenicol.     

花色苷提取、分离纯化及鉴定的研究进展

花色苷是高等植物中最重要的水溶性色素。因其种类繁多、来源广泛、安全无毒并有一定的营养和保健功效而引起国内外的广泛关注,具有十分重要的开发价值和广阔的应用前景。近年来,有关花色苷的研究一直是国内外研究的热点。文中系统地介绍了国内外花色苷提取、分离纯化及鉴定的研究方法,并对各种方法进行了分析评价。     

Influence of time, temperature, moisture, ingredients, and processing conditions on starch gelatinization

Starch gelatinization phenomena is extremely important in many food systems. This review focuses on factors affecting gelatinization characteristics of starch. Important variables which must be considered in design of processes in which starch undergoes gelatinization are heat of gelatinization and temperature of gelatinization. Major interactions are reviewed for the effects of lipids, moisture content, nonionic constituents and electrolytes on these characteristics. Furthermore, treatment of starch-containing systems prior to heating into the gelatinization temperature range can have a significant effect on ultimate gelatinization characteristics.     

Effects of X-ray treatments on pathogenic bacteria, inherent microflora, color, and firmness on whole cantaloupe

Inactivation of inoculated Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri on whole cantaloupes using X-ray at different doses (0.1, 0.5, 1.0, 1.5, and 2.0 kGy) was studied. The effect of X-ray on quality parameters (color and texture) of untreated and treated whole cantaloupes was instrumentally determined. The effect of X-ray on microflora counts (mesophilic counts, psychrotrophic counts and yeast and mold counts) of untreated and treated whole cantaloupes was also determined during storage at 22°C for 20 days. A mixture of three strains of each tested organism was spot inoculated (100 μl), separately, onto the surface (5 cm(2)) of cantaloupe rinds (approximately 8-9 log CFU ml(-1)) separately, air dried (60 min), and then treated with X-ray at 22°C and 55% relative humidity. Surviving bacterial populations on cantaloupe surfaces were evaluated using a nonselective medium (tryptic soy agar) with a selective medium overlay for each bacterium; E. coli O157:H7 (CT-SMAC agar), L. monocytogenes (MOA), and S. enterica and S. flexneri (XLD). More than a 5 log CFU reduction was achieved after treatment with 2.0 kGy X-ray, for all tested pathogens. No significant effect of X-ray treatment on cantaloupe color or firmness was detected. Furthermore, treatment with X-ray significantly reduced the initial inherent microflora on whole cantaloupes and inherent levels were significantly (p<0.05) lower than the control sample throughout storage for 20 days.     

Effect of Freezing, Thawing, Drying, and Cooking on Carotene Retention in Carrots, Broccoli and Spinach

Effects of freezing, thawing, cooking and drying on carotene retention of carrots, broccoli and spinach were evaluated. Relative differences in carotene retention among these vegetables were compared. Dehydration, regardless of drying method, significantly reduced carotene in these vegetables. Carotene contents of fresh, vacuum and microwave dried samples for carrots, broccoli and spinach were 989, 459, 368; 106, 43, 40; and 455, 325, 314 μg/g, respectively. Lag time after thawing decreased mean carotene of vegetables significantly in a quadratic manner. Degradation of carotene was severe 6 hr after thawing, Cooking did not affect carotene and cooked samples contained 2.0, 2.9, and 1.2 times more carotene than the respective dehydrated vegetables. Destruction of carotene was relatively lower when initial concentrations were low.     

Effect of hypothyroidism on hormone profiles in virgin,pregnant and lactating rats,and on lactation

Thyroid dysfunctions can produce reproductive problems. Untreated maternal hypothyroidism has serious consequences on development of offspring, resulting in stunted growth and mental retardation. The effects of propylthiouracyl-induced hypothyroidism (0.1 g l(-1) in drinking water starting 8 days before mating, or given to virgin rats for 30 or 50 days) on the serum profiles of hormones related to reproduction and mammary function (prolactin, growth hormone (GH), progesterone, corticosterone, oestradiol, insulin-like growth factor I (IGF-I), thyroid-stimulating hormone (TSH), triiodothyronine and tetraiodothyronine), and on mammary function in virgin, pregnant and lactating rats, were investigated. Propylthiouracyl treatment severely decreased circulating triiodothyronine and tetraiodothyronine concentrations, and increased serum TSH concentrations. Virgin rats showed prolonged periods of vaginal dioestrus, increased circulating progesterone concentrations and afternoon peaks of prolactin concentration, which are indicative of prolactin-induced pseudopregnancy. Propylthiouracyl-treated virgin rats had mammary development comparable to that of midpregnancy, and half of these rats had increased mammary casein and lactose concentrations. Serum prolactin concentrations were decreased on the afternoon of day 5 of pregnancy, increased during late pregnancy (days 15-21) and were normal during lactation. Circulating GH concentrations decreased on days 15-21 of pregnancy, whereas progesterone concentrations increased during late pregnancy and early lactation. Circulating oestradiol (measured in late pregnancy and in virgin rats), IGF-I and corticosterone concentrations were decreased. Although assessment of mammary histology showed no differences in extent of development, casein content was increased in propylthiouracyl-treated rats on day 21 of pregnancy; litter growth was severely reduced and at day 20 of age the pups were hypothyroid, with decreased GH serum concentrations. An acute suckling experiment was performed on days 10-12 of lactation to determine whether some impairment in mammary function or the suckling reflex might account for these differences. After an 8 h separation of mothers from their litters and 30 min of suckling, circulating prolactin values were not affected by propylthiouracyl treatment, but serum oxytocin concentration and milk excretion were reduced. In conclusion, hypothyroidism induces various alterations in the hormone profiles of virgin and pregnant rats, and induces pseudopregnancies and mammary development in virgin rats. These alterations do not appear to have an overt impact on the outcome of pregnancy and on mammary function during lactation, with the exception of the milk ejection reflex, which may account at least partially for the reduced litter growth.     

Impact of Prior Consumption on Sour,Sweet, Salty,and Bitter Tastes

Food sensory tests generally require panelists to abstain from food or beverage consumption 30 min to an hour before a tasting session. However, investigators do not have a complete control over panelists' intentional or unintentional consumption prior to a tasting session. Currently, it is unclear how prior consumption impacts the results of the tasting session. The aim of this study was to determine the effects of temporary and lingering mouth irritation caused by the consumption of coffee, orange juice, and gum within 1, 15, or 30 min prior to the tasting session on the perception of 4 basic tastes: sweet, salty, sour, and bitter. Fifty‐two panelists were served a beverage (orange juice, coffee, and water) or were asked to chew a piece of gum, and then, remained in the waiting room for 1, 15, or 30 min. They were then asked to report taste intensities using 15‐cm unstructured line scales. Mean intensities of all tastes were not significantly different when orange juice was a primer at 1, 15, and 30 min when compared to water. Mean intensities of bitter were significantly lower when coffee was a primer at 1, 15, and 30 min than when water was a primer. Mean intensities of sweet were significantly lower when gum was a primer at 1 and 15 min than when water was a primer. The findings showed that it is necessary for 30 min or more waiting period of no food or beverage consumption prior to sensory testing.     

Effects of ketones, acetate, butyrate, and glucose on bovine lymphocyte proliferation

Blood leukocytes from age-matched heifers were used to determine effects of ketones, acetate, butyrate, and glucose on in vitro lymphocyte proliferation. Lymphocytes stimulated with concanavalin A, phytohemagglutinin-P, or pokeweed mitogen were cultured in the presence or absence of beta-hydroxybutyrate, acetoacetate, acetone, acetate, butyrate, and glucose. Only supraphysiological levels of beta-hydroxybutyrate inhibited proliferation in cultures of mitogen-stimulated lymphocytes, whereas mixtures of beta-hydroxybutyrate and acetoacetate at levels seen in severe ketosis stimulated concanavalin A and phytohemagglutinin-P-driven proliferation. Because acetoacetate was a lithium salt, lithium chloride served as a negative control. Results suggest the enhanced proliferation by cultures containing lithium acetoacetate was due to lithium, not acetoacetate. Butyrate (at concentrations greater than seen in bovine plasma) and acetate at normal levels inhibited proliferation. Concanavalin A- and pokeweed-mitogen-driven proliferation was greater in cultures containing lower glucose levels, but acetate added to cultures containing low glucose inhibited concanavalin A-stimulated proliferation. Proliferation by pokeweed mitogen-stimulated cultures containing acetate, beta-hydroxybutyrate, and acetoacetate was suppressed at the lower concentrations of glucose tested. In conclusion, ketones, butyrate, and glucose at concentrations occurring in vivo had minimal effects on bovine lymphocyte proliferation in vitro. Levels of acetate associated with ketosis suppressed lymphocyte function and may alter immune responsiveness in vivo.     

Impact of transglutaminase on the textural, physicochemical, and structural properties of chicken skeletal, smooth, and cardiac muscles

This study examined the effects of microbial transglutaminase (MTG; 3.1 mg/ml) on chicken skeletal, smooth, and cardiac muscles; the meat containing the different muscle types was shaped into sausages and treated at 40 °C and/or 78 °C for 30 min. Although the three muscle types were obtained from the same bird, the effects of MTG addition were not uniform. All the muscle types showed a significant increase in the breaking strength (P < 0.01), but skeletal muscle exhibited the maximum increase. All samples showed a decrease in the fluorescence intensity and a significant reduction in the concentration of proteins that were extracted in a high ionic strength solution (P < 0.05). Scanning electron microscopy images and histological studies revealed that different muscle types had different physical structures and frameworks after MTG treatment, which is a reflection of the differences in the reaction specificity of MTG with different muscle proteins. Histological studies revealed that the reactions of MTG with meat proteins are both exogenous and endogenous. Cooking loss data suggested that MTG did not have any negative effect on water retention during cooking. MTG appears to be a functional and contributive substance since the results suggest that MTG can function on all muscle types that are mechanically processed for different industrial applications. MTG aggregates muscle proteins in different ways that improve their organoleptic properties such as texture, appearance, and water retention.     

Impact of transglutaminase on the textural,physicochemical, and structural properties of chicken skeletal,smooth, and cardiac muscles

This study examined the effects of microbial transglutaminase (MTG; 3.1 mg/ml) on chicken skeletal, smooth, and cardiac muscles; the meat containing the different muscle types was shaped into sausages and treated at 40 °C and/or 78 °C for 30 min. Although the three muscle types were obtained from the same bird, the effects of MTG addition were not uniform. All the muscle types showed a significant increase in the breaking strength (P < 0.01), but skeletal muscle exhibited the maximum increase. All samples showed a decrease in the fluorescence intensity and a significant reduction in the concentration of proteins that were extracted in a high ionic strength solution (P < 0.05). Scanning electron microscopy images and histological studies revealed that different muscle types had different physical structures and frameworks after MTG treatment, which is a reflection of the differences in the reaction specificity of MTG with different muscle proteins. Histological studies revealed that the reactions of MTG with meat proteins are both exogenous and endogenous. Cooking loss data suggested that MTG did not have any negative effect on water retention during cooking. MTG appears to be a functional and contributive substance since the results suggest that MTG can function on all muscle types that are mechanically processed for different industrial applications. MTG aggregates muscle proteins in different ways that improve their organoleptic properties such as texture, appearance, and water retention.     

Effect of anolyte on background microflora, Salmonella, and Listeria monocytogenes on catfish fillets

Near-neutral electrolyzed water (anolyte), having a pH of 6.0 to 6.5 ± 0.02, oxidation reduction potential of greater than 700 mV, and a residual chlorine level of 10 to 200 ppm, was reported to have a potential use to decontaminate food surfaces. An electrolyzing cell was developed that is capable of producing neutral electrolyzed water containing a chlorine level of greater than 700 ppm in the form of hypochlorous acid (anolyte). Anolyte with a chlorine level of 300 ppm was used to determine its effect on Salmonella and Listeria monocytogenes cells after a 3-min contact. Transmission electron micrograph results showed disruption of the outer cellular membrane for both bacteria. The anolyte (300 ppm) was used as a washing solution to decontaminate catfish fillets inoculated with either Salmonella or L. monocytogenes. After a 3-min contact time with the anolyte, there was a 1-log reduction for Salmonella, and after 8 days of refrigerated storage (4°C), this bacterial reduction was maintained. There was no reduction of L. monocytogenes on the catfish fillet surfaces. The anolyte was an effective wash solution for Salmonella reduction on the catfish fillet surfaces.