Effects of postmortem temperature and time on the water-holding capacity of hot-boned turkey breast and thigh muscle

Turkey breast and thigh muscles were excised immediately after slaughter and held from 0.25 to 4 h postmortem at 0, 12 or 30 °C to determine postmortem time and temperature effect on muscle pH, drip loss, sarcomere length, homogenate supernatant weight, salt-soluble protein and cooking yields. Higher temperature and longer storage time induced greater drip losses in breast. Longer storage time induced greater drip losses but the least drip loss occurred at 12 °C in thigh muscle. High temperature increased the supernatant weight in breast but decreased that in thigh. Storage time increased supernatant weight and supernatant salt soluble protein levels in both muscles. Homogenate cooking yields of breast containing water, salt and phosphate (HWSP) were higher for 0 and 12 °C compared with 30 °C, and increased with storage. The low postmortem temperature (0 °C) decreased homogenate cooking yields in thigh. These findings indicate that lower postmortem temperatures (0 and 12 °C) and shorter storage time (24 h) produced the greatest water-holding capacity in turkey breast muscle, whereas high and low postmortem temperatures (30 and 0 °C) and longer storage (168 h) produced the least water-holding capacity in raw turkey thigh muscle.     

Influence of Storage Duration and Temperature on Sweet Potato Sugar Content and Chip Color

Sugar concentration and chip color of three orange-flesh and two white-flesh sweet potato cultivars were determined after various lengths of storage at different temperatures. Lightest colored chips were produced from roots chipped immediately after harvest and from cultivars which contained the lowest levels of glucose and fructose. Storage of roots at 32°, 15.6°, or 7°C after harvest resulted in increased sucrose, glucose and fructose concentrations and darker colored chips. Manipulation of storage temperature was not successful in lowering reducing sugar concentration in any cultivar.     

Sensory Quality of Nonfat Dry Milk after Long-Term Storage

Nonfat dry milk was stored under various conditions to determine the effects of temperature, packaging, atmospheric gases, and form of milk on the sensory quality of the stored product. Nonfat dry milk was significantly affected by storage temperature during long-term storage. Nonfat dry milk held at 32°C for 6 mo began to develop offflavors and by 24 mo was considered unacceptable when evaluated by a trained sensory panel. After 4-yr storage nonfat dry milk samples stored at 21°C were rated unacceptable by the panelists. Storage at 10°C resulted in minimal flavor changes in 52 mo. After 4-yr storage, nonfat dry milk samples stored in Polybags were statistically less acceptable than samples stored in cans. The form of milk (instant or regular) did not affect the length of time nonfat dry milk could be stored. Unacceptability of samples was due to an oxidized/stale flavor.     

CONTROLLED ATMOSPHERE STORAGE AFFECTS QUALITY AND CHILLING SUSCEPTIBILITY OF CUCUMBERS

Controlled atmospheres (CA) maintained the quality of cucumbers better than conventional refrigerated storage at 5C. Elevated levels of CO₂ (3%) and decreased concentrations of O₂ (1 and 15%) also increased the tolerance of cucumbers to chilling exposure. The content of sugars, including fructose and glucose; and organic acids, particularly malic acid, were maintained at higher levels in CA-stored cucumbers than in air-stored samples. The respiration rates (measured as CO₂ production) of cucumber fruit during storage at 5C were markedly suppressed under CA conditions. Contrary to reports in the literature, CA storage was found to be beneficial in reducing chilling injury and maintaining cucumber quality.     

Characterization of Shortday Onion Cultivars of 3 Pungency Levels with Flavor Precursor, Free Amino Acid, Sulfur, and Sugar Contents

ABSTRACT:  This study was conducted to characterize shortday onions of 3 pungency levels with regard to the composition of flavor related compounds. A total of 9 onion breeding lines/cultivars were selected, per each of low, medium, and high pungency level, with pyruvic acid contents of 1.9 to 2.8, 4.8 to 5.4, and 7.2 to 8.3 μmoles/mL, respectively. The contents of flavor precursors (S-1-propenyl-L-cysteine sulfoxide [1-PeCSO] and S-methyl-L-cysteine-sulfoxide [MCSO]), free amino acids, free sugars, soluble solids (SSC), and total sulfur (S) in onion bulbs were measured. The flavor precursor contents ranged from 0.03 to 0.16 mg/g fresh weight (FW) for MCSO, 0.07 to 0.65 mg for 1-PeCSO, and 0.12 to 0.77 mg in total, and precursor contents increased with the pungency levels. Onions of different pungency levels did not differ in the contents of individual or total free amino acids, and the most abundant amino acids were glutamine and arginine. The total sugar contents ranged from 50 to 75 mg/g FW, and total S contents (3.5 to 5.1 mg/g dry weight) were not correlated with the pungency levels. However, pungency levels were correlated inversely with bulb weight and positively with SSC, presumably by the effect of dilution. This study indicates that onion pungency is primarily determined by the content of flavor precursor compounds and not by total S, total sugars, or individual/total free amino acids in shortday bulbs.     

Effect of handling and storage on alkylamides and cichoric acid in Echinacea purpurea

Changes in alkylamide and cichoric acid concentrations during the handling and storage of freshly harvested and dried Echinacea purpurea plants were investigated. Plants subjected to varying degrees of physical damage to simulate rough handling were found to show no change in the concentrations of alkylamides and cichoric acid when subsequently dried within 24 h. Storage of undamaged fresh plant material at 20 °C and 60% RH for 30 days also showed no significant loss of either group of constituents. Storage of dried crushed plant material showed that alkylamides were degraded at 20 and 30 °C, especially when held in light, but no loss occurred when stored at 5 °C in the dark. Cichoric acid was found to be stable at 5, 20 and 30 °C provided that the moisture content remained low or enzymic activity was eliminated by blanching. The findings have implications for the handling and storage of echinacea to optimise retention of alkylamides and cichoric acid. © 2000 Society of Chemical Industry     

Calpains and calpastatin from cold-shortened bovine M. longissimus lumborum

Sections of beef longissimus lumborum from four animals were held after 1 hr post mortem at either 0 ° (cold-shortened) or at 15 °C (controls). After 24 hr, the levels of μ- and m-calpains were the same in both treatments and about 30% and 85% of their initial levels respectively. The level of calpastatin at 24 h was higher in cold-shortened (100%) than in controls (60% of its initial level). During subsequent storage at 4 °C, the activities of calpains and calpastatin decreased similarly in extracts from both cold-shortened and control muscles. The similar levels of μ-calpain during the first 24 hr post mortem but at the lower temperature suggest that there is less activity under cold-shortening conditions. This, combined with the increased calpastatin levels, would produce less proteolysis by the calpain system. Reduced proteolysis is therefore a factor which should be considered in an understanding of the mechanism of cold-shortening toughness.     

Effect of high pressure, temperature, and storage on the color of porcine longissimus dorsi

The color of pork longissimus dorsi high pressure (HP) treated at 200 to 800MPa at 5 and 20°C for 10min was determined to a high degree by pressure level and to a lesser degree by temperature. Severe color changes appeared up to a threshold pressure at 400MPa. HP treatment at 20°C compared to 5°C resulted in meat, which was less red and slightly lighter. Storage at 2°C for 6days had no effect on lightness due to no further protein denaturation, but meat HP treated above 300MPa became significantly less red and more yellow within the first day of storage. Reflectance spectra showed that a short-lived ferrohemochrome myoglobin species was formed during HP treatment at 300 to 800, but transformed into a brown, ferric form of the pigment within the first day of storage. This explains the observed changes in the redness and yellowness after one day of storage.     

Effects of cooling and freezing storage on the stability of bioactive factors in human colostrum

Breast milk constitutes the best form of newborn alimentation because of its nutritional and immunological properties. Banked human milk is stored at low temperature, which may produce losses of some bioactive milk components. During lactation, colostrum provides the requirements of the newborn during the first days of life. The aim of this study was to evaluate the effect of cooling storage at 4°C and freezing storage at -20°C and -80°C on bioactive factors in human colostrum. For this purpose, the content of IgA, growth factors such as epidermal growth factor, transforming growth factor (TGF)-β1 and TGF-β2, and some cytokines such as IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α, and its type I receptor TNF-RI, were quantified. Some colostrum samples were stored for 6, 12, 24, and 48 h at 4°C and others were frozen at -20°C or -80°C for 6 and 12 mo. We quantified IgA, epidermal growth factor, TGF-β1, and TGF-β2 by indirect ELISA. Concentrations of IL-6, IL-10, and TNF-α cytokines, IL-8 chemokine, and TNF-RI were measured using the BD Cytometric Bead Array (BD Biosciences, Erembodegem, Belgium). Bioactive immunological factors measured in this study were retained in colostrum after cooling storage at 4°C for at least 48h, with the exception of IL-10. None of the initial bioactive factor concentrations was modified after 6 mo of freezing storage at either -20°C or -80°C. However, freezing storage of colostrum at -20°C and -80°C for 12 mo produced a decrease in the concentrations of IgA, IL-8, and TGF-β1. In summary, colostrum can be stored at 4°C for up to 48 h or at -20°C or -80°C for at least 6 mo without losing its immunological properties. Future studies are necessary to develop quality assurance guidelines for the storage of colostrum in human milk banks, and to focus not only on the microbiological safety but also on the maintenance of the immunological properties of colostrum.     

Sugars and organic acids in Japanese plums (Prunus salicinaLindell) as influenced by maturation, harvest date, storage temperature and period

The effects of fruit maturation, harvest date, storage temperature, storage period and shelf life, on the concentrations of individual sugars and organic acids in Japanese plums were investigated. During fruit maturation in 'Amber Jewel' plums, sucrose concentration increased significantly from 101 days after full bloom (DAFB) to 1 week after commercial maturity (136 DAFB) with a non-significant change in the concentration of total organic acids and malic acid, the major organic acid. The changes in concentrations of sugars and organic acids during cold storage of 'Amber Jewel' plums harvested on 129 and 136 DAFB appeared to be independent of harvest date. Storage of 'Amber Jewel' plums at 5 °C accelerated the loss of sucrose and increased the concentrations of fructose and glucose from the 4^th week of storage compared with those stored at 0 °C. 'Blackamber' plums did not undergo any significant increase in the total and individual sugars during 5 weeks storage and subsequent shelf-life of 8 days at 20 °C. Malic acid concentrations declined during storage from 3 weeks onwards with a further substantial loss during ripening at 20 °C. Maturation, harvest date, storage temperature, storage period and shelf-life affect the concentrations of sugars and organic acids in Japanese plums.     

CHANGES OF SUGAR PROFILES IN CANNED CLINGSTONE PEACHES

The effect of post-canning storage on sugar profiles in canned clingstone peaches (Primus persica var. ‘Halford’) sweetened with various combinations of sucrose, 62 D. E. corn syrup and 42% high fructose corn syrup was investigated. The sugars in the peach syrups were monitored at 1, 20 and 30° C after storage for 0, 6, 9 and 12 months. The individual sugars in the peach syrups were separated and analyzed by high pressure liquid chromatography (HPLC). Storage of the canned peaches at 30° C resulted in a rapid decrease in sucrose and a simultaneous increase in fructose and glucose. The hydrolysis of sucrose was successively slower at 20 and 1°C. It was observed that the sugar profiles were also dependent on the initial concentration of the sugar components, time of storage and acidity of the canned peaches. The concentration of maltose showed great fluctuation during storage. The rapid loss in quality acceptance of canned clingstone peaches at high storage temperature was explained by the changes in sugar profiles and the accompanying undesirable chemical and physical changes.     

SENSORY QUALITY OF GALA APPLES AS INFLUENCED BY CONTROLLED AND REGULAR ATMOSPHERE STORAGE

The sensory quality of Gala apples stored for up to 4 months in delayed controlled atmosphere (CA), regular atmosphere (RA), and a combination of sequential CA and RA storage (CR) was evaluated. Sensory analysis included difference and acceptance testing. Firmness, soluble solids and titratable acidity contents, and volatile flavor profiles were measured analytically. Acceptability decreased with storage time. Apples stored in RA were more acceptable than apples stored in CA or CR; the differences between storage treatment were not significant after 4 months of storage. Firmness decreased with storage time, but was not affected by storage treatment. Soluble solids and titratable acidity contents were not affected by storage treatment or time. Storage treatment, storage time, and lot had a significant effect on the volatile flavor profiles. CA storage and extended storage contributed to decreases in the content of volatile flavor compounds.     

Inhibitory effect of Melastoma candidum D. Don acetone extract on foodborne pathogenic bacteria survival in food products

Melastoma candidum D. Don, a Taiwanese folk medicinal plant, has high levels of antibacterial and bactericidal activity. Our aim was to determine whether and to what extent an acetone extract of this plant inhibits the growth of foodborne pathogenic bacteria. M. candidum acetone extract had marked inhibitory effect on test bacteria introduced into sliced pork, which was then stored at 4 degrees C. At the end of storage (day 12), the bacterial concentrations dropped by 1.59 to 2.91 log CFU/g compared with the control. In steamed rice stored at 30 degrees C, a 0.2% extract decreased initial (before storage) concentrations of Bacillus cereus from 2.01 log CFU/g to an undetectable level, which remained for at least 24 h. After 72 to 168 h of storage, test bacterial concentrations were reduced by 2.59 to 5.66 log CFU/g. In fresh noodles stored at 30 degrees C, both initial and final bacterial concentrations were decreased. At the end of storage (72 to 168 h), test bacteria concentrations were reduced by 1.85 to 2.88 log CFU/g. Overall, M. candidum acetone extract had an inhibitory effect on foodborne pathogenic bacteria in different food model systems.     

Effect of Storage Temperature, Time, and Method of Slicing on Microbial Population and White Film Development in Vacuum Packaged, Dry-Cured Ham Slices

Aged ham slices, bone-in or boneless, were vacuum-packaged and stored at 2°C or 24°C for 8 wks. White film was more abundant on bone-in slices. Color was not affected by treatment. Aroma remained normal at 2°C for all slices but abnormal aromas developed in some 24°C packages by 2 wk and in all packages by 8 wk. Aerobic and staphylococci counts on bone-in and boneless slices at 24°C were high at 2 wk and remained high, while lactobacilli counts were highest at 2 wk, decreased to initial levels by 4 wk and increased again to 8 wk. Yeast and mold counts at both temperatures decreased with storage but at a faster rate in bone-in hams.     

Modelling post-mortem tenderisation-II: Enzyme changes during storage of electrically stimulated and non-stimulated beef

Levels of calpains I and II, cathepsins B and L and β-glucuronidase were determined in extracts of electrically stimulated and control beef M. Pectoralis profundus stored at temperatures between 0 and 30°C and varied to avoid muscle shortening. The level of lysosomal enzymes remained essentially unchanged throughout storage. The levels of calpain II were largely unaffected by the early treatments and decreased slightly throughout ageing. The level of calpain I, in both stimulated and control meats, was unaffected by temperature prior to the attainment of about pH 6·2 and thereafter the loss was accelerated at higher temperatures. In the extreme case studied, that of stimulated meat held at 15°C, 73% of the activity was lost in the first 24 h. After ageing, the level was about 11% of the initial when stored at 1°C and 25% when stored at 15°C. The exponential decay constants for the decrease in the levels of calpain I were 0·01 h(-1) at 1°C and 0·06 h(-1) at 15°C, and were the same as those for the previously determined rate of tenderisation. This suggested that the rate of proteolysis by calpain I was linked to the rate of tenderisation.     

Stability of Non-Pasteurized, Refrigerated Muscadine Grape Juice

The stability of nonpasteurized muscadine grape juice processed with and without 100 mg/L potassium metabisulfite was monitored during storage at 3°C. The muscadine flavor intensity, sweetness, off-flavor levels, and color of white juices remained stable, and ethanol levels remained low for 7 wk. However, the flavor intensity and sweetness of nonsulfited white juice decreased, and off-flavor and ethanol levels increased after 7 wk. Sulfite lowered microbial levels in white juice throughout 9 wk. Red juices did not develop significant levels of off-flavors or ethanol during 9 wk, although the flavor intensity declined, especially in nonsulfited red juice. Sulfite lightened the color of red juice, but the color was stable in both sulfited and nonsulfited red juices.     

Effect of storage conditions on lipid components and color of Mugil cephalus processed roes

The salted and semidried mullet (Mugil cephalus) ovary product (bottarga) is proposed as an important source of the long-chain n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid, and docosahexaenoic acid. In this work, we investigated the extent of lipid oxidation and browning of grated bottarga samples during 7 mo of storage at -20 °C, 2 to 3 °C in the absence of light, and at room temperature in the presence or absence of light. Modifications of the levels of total choline (as index of phospholipid breakdown), total sugars, and free amino acids such as lysine, methionine, and tryptophan (involved in nonenzymatic browning) were also studied at different storage conditions. Storage of bottarga did not significantly affect the n-3 PUFA and cholesterol levels with respect to the control; nevertheless, a significant hydroperoxide increase was observed during 7 mo in bottarga samples at all the storage conditions, while low malondialdeyde levels were measured. Samples placed at room temperature in the absence and in the presence of light showed over time a marked browning process, lipid breakdown, a sensible decrease in the levels of total sugars, tryptophan, and methionine with respect to control and samples stored at -20 °C and 2 to 3 °C. The resistance against the oxidation of the isolated bottarga lipids was also assessed in dry state at several temperatures (37, 75, and 140 °C). PRACTICAL APPLICATION: We evaluated the change in lipid compounds and color of dried and salted mullet roes under different storage conditions. The obtained results suggest the importance of the low temperatures to preserve the nutritional properties of this fish product during long storage.     

Monitoring of cocoa volatiles produced during roasting by selected ion flow tube-mass spectrometry (SIFT-MS)

Selected ion flow tube-mass spectrometry (SIFT-MS) was used to measure the real-time concentrations of cocoa volatiles in the headspace during roasting. Alkalized and unalkalized Don Homero and Arriba cocoa beans were roasted at 120, 150, and 170 °C in a rotary roaster. The concentrations of total alcohols, acids, aldehydes, esters, ketones, and alkylpyrazines increased, peaked, and decreased within the timeframe used for typical roasting. The concentrations of alkylpyrazines and Strecker aldehydes increased as the roasting temperature increased from 120 to 170 °C. For most of the volatile compounds, there was no significant difference between Arriba and Don Homero beans, but Arriba beans showed higher concentrations of 2-heptanone, acetone, ethyl acetate, methylbutanal, phenylacetaldehyde, and trimethylpyrazine. For unalkalized Don Homero beans (pH 5.7), the time to peak concentration decreased from 13.5 to 7.4 min for pyrazines, and from 12.7 to 7.4 min for aldehydes as the roasting temperature increased from 120 to 170 °C. Also, at 150 °C roasting, the time to peak concentration was shortened from 9 to 5.1 min for pyrazines, and from 9.1 to 5 min for aldehydes as the pH increased from 5.7 to 8.7. PRACTICAL APPLICATION: SIFT-MS allows for real-time monitoring of the key volatile compounds contributing to chocolate flavor, with minimal sample preparation, thus can be used to facilitate adjusting the roasting conditions, such as temperature and time, to optimize chocolate flavor during roasting. Real-time monitoring during roasting can also be used to evaluate the flavor quality of different types of beans by comparing the concentrations of key flavor compounds.     

Quality Changes in Diced Onions Stored in Film Packages

Effects of a potassium permangenate gas absorbent and storage at 2°C on quality changes in modified atmosphere packaged diced onions was studied. A 3 mil packaging film resulted in equiIibrated O₂ of 2.65% and CO₂ level of 3.65%. Gas absorbent resulted in reduced ethylene, carbon dioxide and sulfur volatiles. Maximum shear force values and total phenolics increased during storage, but were not affected by gas absorbent. Glucose and fructose concentrations declined within one day after processing, which coincided with an increase in sucrose. Sugar concentrations remained stable thereafter, and were not affected by gas absorbent. Microbe colony forming units (CFU) increased during storage to 5.8 in controls and 7.1 (log CFU/g) in absorbent treated samples after 10 days at 2°C.