Ascorbic Acid and Folic Acid Content and Sensory Characteristics of Dehydrated Green Peppers

Moisture content, water activity, ascorbic and folic acid content, and color of blanched and unblanched green peppers, dried for 8 or 9 hr at 60°C or 12 hr at 49°C, were determined before and after 8 wk storage at room temperature. Sensory characteristics of the peppers were evaluated after storage. Blanching influenced ascorbic acid content, color, firmness, and intensity of green pepper, sweet and bitter flavor. Time and temperature of drying influenced water activity and some texture attributes.     

Employing an intelligence model and sensitivity analysis to investigate some physicochemical properties of coated bell pepper during storage

The objectives of this work were to study the effects of three different coatings (gum Tragacanth, sesame oil and gum Tragacanth–sesame oil), temperature and time on shelf life of bell pepper. Moisture reduction, shrinkage as well as firmness and colour changes were studied during 30 days at 4, 10, 15 and 23 °C. Results of this study showed that bell peppers treated with gum Tragacanth at higher temperatures, such as 10 °C, had good quality up to 30 days of storage. However, sharp changes in physicochemical characters were observed in bell peppers stored at 23 °C. In order to predict moisture reduction, shrinkage, firmness and colour changes genetic algorithm–artificial neural network model was developed. It was found that artificial neural network with eight hidden neurons truly could predict the physicochemical changes of bell pepper during storage (R² > 0.9598). The results of sensitivity analysis showed that shrinkage percentage and also changes of firmness and colour were very sensitive to storage time, while storage temperature had the most effect on moisture reduction.     

Impacts of storage temperature and rice moisture content on color characteristics of rice from fields with different disease management practices

Rice downgrading due to discoloration in storage presents a significant loss to growers and processors. The objective of this study was to investigate impacts of storage temperature and rice moisture content (MC) on color characteristics of milled hybrid rice (cv. XL 745) from fields with differing production practices. Freshly-harvested rough rice from field plots treated with and without fungicide for rice disease control during production were procured and stored at four MC levels (12.5%, 16%, 19% and 21% wet basis), and at five temperatures (10 °C, 15 °C, 20 °C, 27 °C, 40 °C) for 16 weeks, with samples taken every 2 weeks. Kinetics of mold growth and rice color were determined. It was observed that at 12.5% MC, discoloration was abated across all studied temperatures and treatments until 6 weeks of storage and increased not in excess of 20% thereafter 16 weeks. As the storage MC increased to 16%, discoloration increased and became significantly notable at the highest temperature of 40 °C. By week 16, at 40 °C storage temperature, discoloration increased significantly to 87.9% and 73% for sample lots from fungicide and non-fungicide treated plots, respectively. At the highest MC (21%), increase in rice discoloration was notable as early as after 2 weeks, across all storage temperatures, and continued to increase, especially for the highest storage temperature of 40 °C, to as high as 99.1% and 96.47%, after 16 weeks, for sample lots from fungicide and non-fungicide treated plots, respectively. There was more expression of discoloration patterns on samples stored at the highest temperature of 40 °C compared to that at lower temperatures, for both categories of sample treatments and ranges of studied MCs. Although not yet widely used for rice, this study suggested that cooling technology for rice, may have potential to extend rice storability, especially by retarding discoloration in the first few weeks after harvest.     

Characterization of volatiles from cultured dairy spreads during storage by dynamic headspace GC/MS

The effect of storage time and storage temperature on the formation of volatile compounds in dairy spreads was investigated. Dairy spreads were stored for 10 weeks at -18, 5 and 20 °C, respectively, and analyzed after 0, 38, 54 and 67 days of storage. By means of a dynamic headspace GC/MS method using Tenax traps the dairy spreads were analyzed for volatile aromatic compounds. 61 components were identified and their relative content was followed during the storage period. Among these were four alcohols, 17 aldehydes, four esters, ten alkanes, 11 ketones and six lactones. A general increase in the concentration of most of the volatile compounds during storage was found. The content of volatile compounds in dairy spreads stored at -18 °C was nearly constant or showed a rather low increase in the content during the storage period. Storage at higher temperatures (5 and 20 °C) resulted in an increase in the content of most of the volatiles after 40 days of storage. The profiles obtained were subjected to multivariate data analysis to determine the volatiles potentially responsible for oxidized off-flavors in dairy spread. The volatiles were divided into three groups: one correlated with storage temperature and 5 °C, one with storage time and 20 °C and the last with storage time alone. Most of the volatiles were found in the highest concentration after storage at 20 °C, but the content of some volatiles was highest after storage at 5 °C.     

Stability of Precured Beef Blends

Preblends of lean beef were prepared using 20% water, 75 ppm nitrite, 3 or 6% salt (based on raw meat wt.) and stored at – 10, 0 and 15°C for 3 days. The nitrite levels in preblends were drastically reduced at 15°C storage temperature; but, after the initial loss following nitrite addition, the residual nitrite remained almost unchanged for products stored at 0 and – 10°C. Samples stored at 15°C increased in microbial numbers during storage and neither 3% nor 6% salt prevented this increase. Samples at both salt levels stored at 0°C or – 10°C did not show a significant change in bacterial numbers during storage. Salt and storage temperature had a significant effect on TBA values, with 6% salt resulting in higher TBA values than 3% salt and storage at 15°C resulting in higher TBA values than storage at 0 or ?10°C.     

Localization,Growth, and Inactivation of Salmonella Saintpaul on Jalapeño Peppers

Abstract: Consumption of Salmonella-contaminated jalapeño peppers has been implicated in one of the largest foodborne illness outbreaks in the summer of 2008. The objective of this study was to investigate representative groups of native microflora and the distribution, growth, and inactivation of experimentally-inoculated Salmonella Saintpaul on jalapeño peppers. Two genetically modified strains of Salm. Saintpaul producing either green- or red-fluorescent protein were constructed and used in the study. Microbiological analyses showed that jalapeño peppers contained an average of 5.6 log units of total aerobic count and 3.5, 1.8, and 1.9 log units, respectively, of enterobacteriaceae, lactic acid bacteria, and yeast/mold per gram of tissue. Strains typical of Pseudomonas accounted for 8.3% of total aerobic count, and 0.2% of which exhibited pectolytic activity. On inoculated peppers, a vast majority (>90%) of Salm. Saintpaul was recovered from stem/calyx and only a small proportion recovered from fleshy pods. Growth of Salm. Saintpaul on peppers was indicated by an increase in the population of 3 log units after incubation of samples at 20 °C for 48 h. Fluorescent Salm. Saintpaul aggregates could be readily detected on stem/calyx using stereofluorescence imaging microscopy and scanning electron microscopy. Data presented showed that Salm. Saintpaul could survive for at least 8 wk on peppers stored at 4 °C. Immersion of inoculated peppers in 200 ppm of sodium hypochlorite, acidified sodium chlorite, or peroxy acetic acid for 10 min could reduce the number of Salm. Saintpaul on stem/calyx by 1.5 to 1.7 and that on flesh by 2.1 to 2.4 log units. Practical Application: Consumption of Salmonella-contaminated jalapeño peppers has been implicated in foodborne illness outbreaks. The vast majority of Salmonella Saintpaul recovered from inoculated jalapeño peppers (>90%) was from stem/calyx. Salmonella increased by 3 log units during storage at 68 °F (20 °C) for 48 h. Salmonella could survive for at least 8 wk on peppers stored at 4 °C. Immersion of inoculated peppers in 200 ppm of sodium hypochlorite, acidified sodium chlorite, or peroxyacetic acid for 10 min reduced Salmonella on stem/calyx by 1.5 to 1.7 log units, compared with reductions of 2.1 to 2.4 log units on flesh. These results highlight the need to consider the stem/calyx as the most likely area for contamination of jalapeño peppers, and to process this commodity accordingly to minimize exposure and cross-contaminations.     

Application of partial autoproteolysis to extraction of protein from Antarctic krill (Euphausia superba). Part 3. Changes in and yield of nitrogen substances during autoproteolysis of fresh and frozen krill

Respective utilities of the fresh and frozen (after a 10-month storage at ?21 °C) krill for precipitate production by means of partial autoproteolysis within 10–60 °C were compared. The highest yield of the precipitate was found at about 20 °C, regardless of the raw material used, although the optimal temperature ranges for the fresh and frozen krill were 20–30 °C and 10–20 °C, respectively. The main factors assisting the protein extraction during partial autoproteolysis were enzymatic protein hydrolysis in the fresh krill and the loosening of tissues brought about by water crystallization in the frozen krill.     

Effects of Processing Treatments on Recovery of Capsaicin in Jalapeno Peppers

Capsaicin content in frozen, cooked and canned jalapeno peppers was quantified using GLC analysis and compared to the capsaicin content in raw peper. The frozen peppers were blanched for 3 min and stored at -18°C; canned peppers were blanched for 3 min and processed at 100°C for 50 min; cooked peppers boiled at 100°C for 10 min. Results demonstrated a significant difference (a = 0.05) between each treatment and the raw pepper. Frozen and canned peppers retained approximately one-half of the capsaicinoid compounds that were present in raw pepper.     

Effect of canning and storage on carotenoids (vitamin A activity) and vitamin C in Spanish and Turkish oranges

Canning caused a small reduction in the vitamin C content of orange purée of both Spanish and Turkish varieties; subsequent storage for 24 months at 10°C caused complete loss of vitamin C. Carotenoids, however, were retained to a limited extent after storage and similar amounts were present at both room temperature and at 10°C. Most of the vitamin C in the flavedo was retained after 24 months' storage at - 20°C but there was a considerable fall when the frozen material was thawed and stored at room temperature for 4 days. Thirteen carotenoids were present in both varieties of purée, with three additional ones in the Spanish variety and one additional one in the Turkish variety. Despite the heating in acid conditions involved in the canning process, only two of the pigments, violaxanthin and flavoxanthin, isomerised from the all-trans to cis-trans isomers.     

Shelf Life and Quality of Freshly Squeezed, Unpasteurized, Polyethylene-Bottled Citrus Juice

Florida's chief orange and grapefruit cultivars were used to produce five freshly squeezed, unpasteurized, polyethylene-bottled juices using commercial conditions. Juices were stored at different temperatures. Shelf life depended primarily on storage temperature: ?1.7°C, 20–23 days; 1.1°C, 16–22 days; 4.4°C, 10–16 days; and 7.8°C, 5–8 days. Staleness was the primary off-flavor limiting shelf life at the three lower temperatures while spoilage with diacetyl was primarily responsible at 7.8°C. At the three lower temperatures, microbial counts generally decreased markedly during storage, while at 7.8°C, an increase was generally noted. Ascorbic acid retention after 2 wk of storage at the three lowest storage temperatures was about 91–93% for two orange juices and 86–88% for the grapefruit juice.     

Spore-forming bacteria in commercial cooked,pasteurised and chilled vegetable purées

In commercial purées of broccoli, carrot, courgette, leek, potato and split pea, pasteurized in their final packaging and analysed at two periods, Bacillus spp. were the dominant aerobic mesophilic bacteria (AMB). Initial numbers were generally lower than 2 log cfu g⁻¹. They increased up to 6–8 log cfu g⁻¹after about 20 days of storage at 10°C. At 4°C, numbers of AMB after 20 days were lower than 3 log cfu g⁻¹in potato purée, lower than 4 log cfu g⁻¹in leek purée, and between 3 and 6 log cfu g⁻¹in other products. Strict anaerobes were in markedly lower numbers than AMB. At all storage temperatures tested courgette purée usually showed the most rapid bacterial growth and spoilage. On this product, an increase in storage temperature from 4°C to 10°C resulted in a threefold reduction in time to 5 log cfu g⁻¹, and time to spoilage. Growth kinetics of AMB in courgette purée at 20°C, 15°C, 10°C, 6·5°C and 4°C were determined using a mathematical model. Three hundred and forty eight isolates were identified using the API system. Bacillus circulans, B. macerans and B. polymyxa were among the main species isolated from products stored at 4°C and 10°C, while B. subtilis and B. licheniformis were the dominant species in product stored at abuse temperature. Bacillus cereus was isolated from all storage conditions, but mostly from products stored at abuse temperature.     

Effect of storage temperature on galactose formation in UHT milk

Galactose has been studied from the standpoint of its suitability as a heat-induced parameter for processed milk. Galactose content in two directly and two indirectly UHT treated liquid milk samples were studied during storage until the end of its shelf-life (12 weeks) period at temperatures of 6, 20, 30, 40, and 50°C. No significant differences during storage were found with reference to the type of thermal process applied, nor with respect to the initial galactose content of the sample. Galactose formation was just directly related to storage time and temperature, being more significant at temperatures higher than 20°C. Galactose increased slightly during storage at ambient temperature (20°C) after the first weeks but kept constant under temperature of refrigeration until end of storage. Thermal history of the processed milk, mainly at a temperature above 20°C, could affect the usefulness of galactose as a heat-induced parameter.     

EFFECTS OF SHRINK FILM WRAP ON INTERNAL GAS CONCENTRATIONS, CHILLING INJURY, AND RIPENING OF HONEYDEW MELONS

Honeydew muskmelons (Cucumis melo L.) were individually wrapped with polyvinyl chloride (PVC) shrink film and stored at 2.5° or 7.5 °C for 21 days and examined, then held an additional 2 or 3 days at 20°C and examined again. Nonwrapped melons were the control. The concentration of CO₂ in the cavity of wrapped melons stored 21 days was 5.6% at 2.5°C, 9.1% at 7.5°C, but only 1.1% and 1.5% in the nonwrapped held at 2.5°C or 7.5°C, respectively. Wrapped fruit ripened slower than nonwrapped fruit during storage and subsequent holding at 20°C, after which time 70% of the wrapped melons were rated eating ripe, but 62% of the controls were overripe. Wrapped melons exhibited 30% less chilling injury (CI) symptoms than nonwrapped fruit stored at 2.5°C. The CI symptoms ranged from reddish-brown to dark-brown surface discolorations and sometimes included dry sunken areas of skin. Fresh weight loss was about 1 % in wrapped melons, but 5% in nonwrapped fruit, regardless of storage temperature. Decay incidence was about equal in wrapped and nonwrapped melons after storage at 2.5°C, but was greater for wrapped than nonwrapped melons after storage at 7.5°C. Soluble solids content was about 12.5% in wrapped and nonwrapped melons stored at either temperature.     

Bioactive amines changes in raw and sterilised milk inoculated with Pseudomonas fluorescens stored at different temperatures

The presence of bioactive amines in raw and sterilised milk inoculated with Pseudomonas fluorescens during storage at 4°C, 7°C and 10°C for 6 days was investigated. Spermine, spermidine, putrescine, serotonin and phenylethylamine were present in the samples immediately after milking. Histamine, cadaverine and tyramine were formed in the raw milk on the 4th day of storage at 10°C, increasing significantly afterwards. Cadaverine was formed during sterilisation. There was no significant change in amines, acidity, thermostability and alizarol tests throughout storage of the sterilised milk; however, a putrid smell was detected at every temperature on the 6th day. Therefore, raw or sterilised milk storage at 4–7°C should not exceed 4 days. Furthermore, raw milk should not be stored at 10°C.     

Effect of cream aging temperature and agitation on butter properties

Aging of cream is an important process to manage production time and to produce butter with consistent quality. The objective of this study was to evaluate the combined effect of temperature (5, 10, and 15°C) and agitation rate (0, 40, and 240 rpm) during aging of cream on the physical properties of cream and butter in a model system. Cream's solid fat content (SFC), melting behavior, and droplet size distribution were measured during and after 90 min of aging. Butter physical properties such as melting behavior, water content, and hardness were measured. The effects of agitation on SFC and droplet size are dependent on aging and churning temperature. Solid fat content increased faster at 5°C, and the maximum SFC was the highest at this temperature. An effect of agitation on SFC was observed only when cream was aged at 15°C. Agitating cream at 40 rpm increased the droplet size regardless of aging temperature. Two melting peaks, medium melting fraction (MMF) and high melting fraction (HMF), were found in cream samples aged at 5 and 10°C, but only a HMF melting peak was seen in the cream aged at 15°C. The enthalpy of MMF in the cream aged at 10°C with 40 rpm and without agitation was significantly lower than that in samples aged at 5°C regardless of agitation rate. Butter can be formed only from cream aged under certain conditions during 14.5 min of churning, which are 5°C with high agitation and 10°C regardless of agitation level. Butter produced with cream aged at 5°C with high agitation showed significantly higher MMF and total enthalpy values. However, no significant difference in enthalpy values was observed among the butter samples made from the cream aged at 10°C. Further crystallization of MMF occurred in the butter produced with cream aged at 10°C during 24 h of storage at 5°C, whereas no further crystallization occurred in the butter made with the cream aged at 5°C with high agitation. The hardest butter was obtained when cream was aged at 5°C with 240 rpm and at 10°C with 40 rpm. Softer butter was obtained when cream aged at 10°C with 240 rpm was used. This butter also had the highest water content. This study shows that butter hardness can be tailored by changing the aging conditions of the cream. Cream can be aged at higher temperature with low agitation without altering the hardness of butter. These results will help dairy producers to optimize butter making processes to obtain desired properties in the final product.     

Variations in Internal Color of Cooked Beef Patties

Seventeen commercially prepared patty formulations were cooked to internal temperature 71°C. Pink cooked color occurred in eight of the products and was due to incomplete denaturation of myoglobin. Although there was some relation between pH and cooked color, other factors seemed to be involved. When products were re-analyzed after 1 yr storage at -27°C, sixteen products were red/pink when cooked to 71°C. This increase in redness after frozen storage could not be explained. Cooking to internal temperatures between 81 and 87°C was necessary for complete disappearance of red/pink color. Premature browning, where a product looks well-done at temperatures lower than 71°C, occurred in one formulation.     

Developmental period and mortality of Gnathocerus maxillosus (F.) (Coleoptera,Tenebrionidae) under various conditions of temperature and humidity

When fed on a 10:1 mixture of wheat flour and yeast, Gnathocerus maxillosus (F.) completed development over the temperature range 20–35°C at most experimental humidities. As expected, the developmental period decreased with higher temperatures and humidities. However, at 100% r.h. insects were often overwhelmed by mould, nor did they survive at humidities below 33% r.h. Mortality exceeded 20 per cent except at the mid-range of humidities at 30°C and higher humidities at 27·5 and 25°C. These developmental data indicate that this pest is well adapted to storage conditions of cereals and other stored products.     

The influence of storage on aroma, soluble solids, acid and colour of sour cherries (Prunus cerasus L.) cv. Stevnsbær

The present study involved a laboratory scale experiment where the impact of post-harvest storage on the quality of sour cherries (Prunus cerasus L.) cv Stevnsbær was investigated. Cherries were stored for 7 days at temperatures of 2??°C, 10??°C, 20??°C, and 30??°C, and at 20??°C in combination with a 20% CO₂ atmosphere. Cherry quality was assessed by analysis of soluble solids, titrateable acids, anthocyanins and aroma compounds. The content of soluble solids of cherries decreased at storage temperatures above 10??°C. The anthocyanin content of cherries decreased during storage at all temperatures. A decrease, followed by an increase, in titrateable acid was observed for all temperatures except 2??°C. Aroma components were also affected by storage time and temperature. The level of benzaldehyde decreased during storage at higher temperatures, while those of eugenol and vanillin increased at all temperatures. The levels of "off" odour compounds, like acetic acid and fermentation alcohols, increased at higher temperatures during storage. The CO₂-enriched atmosphere (20%?CO₂) did not affect the different quality factors significantly.     

The effect of the high pressure homogenisation on the activity and stability of a commercial neutral protease from Bacillus subtilis

The activity of a commercial neutral protease from Bacillus subtilis after high pressure homogenisation (HPH) was investigated. The enzyme was processed up to 2000 bar, and the residual activity was measured from 20 to 70 °C during refrigerated storage. Moreover, the effect of HPH at high temperatures was evaluated. No improvement in the activities at 55–70 °C were observed after HPH, while an increase of approximately 30% in the 20 °C‐activity was reached after 2000 bar processing. Thus, HPH shifted the optimum temperature from 55 to 20 °C. The high temperature homogenisation caused no changes in 55 °C‐activity, but reduced 20 °C‐activity three times. It suggests that HPH modifies the protease configuration, changing enzyme performance (maximum activity condition), as the efficacy of lock‐and‐key mechanism is strictly dependent on enzyme spatial structure. The changes can be permanent or not, depending on homogenisation pressure, inlet temperature and enzyme storage conditions. Therefore, the HPH is a promising method to change protease characteristics.     

Optimizing storage temperature of liquid bovine semen diluted in INRA96

Temperature regulation of liquid bovine semen can be difficult in field situations. Two experiments were carried out to assess the effect of storage temperature on in vitro sperm characteristics and 60-d nonreturn rate (NRR) following artificial insemination (AI) of liquid bovine semen. In experiment 1, the effect of storage of liquid bovine semen in INRA96 diluent (IMV Technologies, L'Aigle, France) at 1 of 5 storage temperatures (5, 15, or 28°C, and fluctuating between 5 and 15°C or 5 and 28°C) on total and progressive motility and kinematic parameters was assessed objectively via computer-assisted sperm analyzer on d 0, 1, 2, 3, and 4 after collection. Fluctuating temperatures were designed to mimic day- to nighttime variation. In experiment 2, we assessed the field fertility of liquid semen stored at a constant 5 or 15°C or in an unregulated manner and compared with that of frozen-thawed semen (total of n = 106,738 inseminations). In experiment 1, we detected a linear decrease in motility with increased duration of storage. Semen stored at a constant 15°C or fluctuating between 5 and 15°C had greater total motility than semen held at 5 or 28°C or fluctuating between 5 and 28°C; however, semen stored at 15°C and fluctuating between 5 and 15°C did not differ from each other. Semen held at a constant 5 or 15°C or fluctuating between 5 and 15°C, although not differing from each other, had higher progressive motility scores than that held at 28°C or fluctuating between 5 and 28°C. Semen stored at a constant 28°C exhibited poor motility and velocity values but had high progressive motion values compared with that all other storage temperatures; however, the other storage temperatures did not differ from each other in relation to motility kinematics. In experiment 2, semen stored at a constant 5°C resulted in a lower 60-d NRR (62.5%) than storage at constant 15°C or unregulated temperature or frozen-thawed semen (73.6, 74.6, and 74.4%, respectively. In conclusion, sperm stored in IRNA96 are quite tolerant in terms of storage temperature, retaining acceptable motility between 5 and 15°C. Storing semen at a constant 15°C resulted in greater in vitro sperm motility and higher NRR rates than storage at 5°C and did not differ in NRR from frozen-thawed semen or semen stored at an unregulated temperature; however, lower storage temperatures were shown to be more detrimental to sperm in vivo than unregulated storage conditions.