Homogenization and thermal processing reduce the concentration of extracellular vesicles in bovine milk.

Extracellular vesicles (EVs) in bovine milk confer beneficial physiologic effects to consumers. Industrial processing treatments may affect the amount or bioactivity of EVs intrinsic to bovine milk. We investigated how the content and concentration of EVs were affected by homogenization and thermal processing of raw bovine milk. Raw milk was processed by homogenization, low-temperature (LT) heat, or pasteurization [high-temperature short-time (HTST) and ultra-high-temperature (UHT)] in a pilot processing facility. EVs were isolated from the raw and processed bovine milk using differential ultracentrifugation and quantified using a nanoparticle tracking analyzer. Bovine milk EVs were assessed for total miRNA and protein concentrations standardized to particle count using a fluorometric assay. There were 1.01 × 1010 (±3.30 × 109) EV particles per ml of bovine milk. All industrial processing treatments caused >60% decrease in EV concentration compared to the raw bovine milk. Homogenization and heat treatments independently and additively reduced the content of EVs in bovine milk. The averages of total miRNA/particle and total protein/particle concentrations were elevated threefold by low-temperature heat-processing treatment relative to HTST and UHT pasteurizations. The average diameter of EVs was reduced by 11%-16% by low temperature compared to raw milk (127 ± 13 nm). Homogenization and pasteurization indiscriminately reduce the EV concentration of bovine milk. Smaller EVs with higher protein content resist degradation when processing bovine milk at sub-pasteurization temperature. This new foundational knowledge may contribute to food product development on the preservation of EVs in processed dairy products, including bovine milk-based infant formulas that some newborns are dependent on for adequate growth and development.

Exploring pathways to food science careers in Southern California: A case study in food science career development.

Southern California is a diverse region that is home to a high concentration of food science companies, with an increasing demand for additional food scientists and technologists to join this workforce. Despite this abundance of food science companies and the high demand for jobs, there is currently a shortage in the number of qualified food scientists and technologists in the region. This shortage is also observed within higher education, with declining enrollments in the food science graduate and undergraduate programs across Southern California. Here, we conduct a case study to explore the factors that influence students from Southern California to pursue or not pursue careers in food science. We surveyed both undergraduate and graduate students currently enrolled in food science as well as industry professionals in the region to determine sources of knowledge about the discipline, and motivations and barriers for pursuing careers in food science. We also surveyed high school educators in the region to gain additional perspectives on how food science is being introduced at the secondary level, if at all. Our results demonstrate that many students and high school educators are not knowledgeable about career options within food science and that students who are pursuing food science largely report similar motivations for pursuing the discipline as those currently working in the food science industry. We conclude by discussing implications for the food science education community within Southern California and beyond.

Resistance Training Threshold for Elevating Bone Mineral Density in Growing Female Rats.

The purpose of this study was to determine the minimum amount of resistance exercise that would stimulate bone formation yielding an elevation in bone mineral density (BMD) during the growth period in female rats. Female rats were randomly divided into: Control (Con, n=8), 3 ladder climb resistance-trained group (3LC, n=8), 4 ladder climb resistance-trained group (4LC, n=8), 5 ladder climb resistance-trained group (5LC, n=8), and 6 ladder climb resistance-trained group (6LC, n=8). All exercised groups were conditioned to climb a vertical ladder with weights appended to their tail 3 days/wk for a total of 6 wks. After 6 wks, left tibia BMD (g/cm2) was significantly greater for 4LC (0.197±0.003), 5LC (0.200±0.004) and 6LC (0.202±0.003) when compared to Con (0.185±0.006). Left femur BMD (g/cm2) was significantly greater for 4LC (0.260±0.005), 5LC (0.269±0.004) and 6LC (0.272±0.006) when compared to Con (0.244±0.006). There were no significant differences in tibia and femur BMD between 4LC, 5LC, and 6LC groups. The results suggest that during growth, a high volume of resistance exercise was required to elicit an elevation in BMD in females.

Effect of phytosanitary irradiation on the postharvest quality of Seedless Kishu mandarins (Citrus kinokuni mukakukishu).

Transnational trade of 'Seedless Kishu' mandarins (Citrus kinokuni mukakukishu) would require them to be subjected to a suitable phytosanitary treatment. Irradiation is used as an effective treatment for many fruit, but the effect on quality of kishu mandarins is unknown. 'Seedless Kishu' mandarins were treated with gamma irradiation (150, 400, and 1000Gy) and stored for three weeks at 6°C and then for one week at 20°C. Irradiation at 400 and 1000Gy promoted browning of the calyx end and fungal infection. Irradiation caused immediate reductions in pulp firmness, vitamin E, individual sugars and carotenoids but increased the content of organic acids, except ascorbic acid, and phenolic compounds. The volatile profile of tested fruit was also differentially altered by irradiation. Most of these initial changes were dose dependent. 'Seedless Kishu' mandarins are significantly sensitive to irradiation and are not suitable for treatment at the studied doses.

Effect of phytosanitary irradiation and methyl bromide fumigation on the physical, sensory, and microbiological quality of blueberries and sweet cherries.

BACKGROUND: The objective of this study was to determine whether irradiation could serve as a suitable phytosanitary treatment alternative to methyl bromide (MB) fumigation for blueberries and sweet cherry and also to determine the effect of phytosanitary irradiation treatment on survival of Salmonella spp. and Listeria monocytogenes on these fruit. 'Bluecrop' blueberries (Vaccinium corymbosum) and 'Sweetheart' cherries (Prunus avium) were irradiated at 0.4 kGy or fumigated with methyl bromide and evaluated for quality attributes during storage. RESULTS: Irradiation caused an immediate decrease in firmness of both fruit without further significant change during storage. Fumigated fruit, in contrast, softened by 11-14% during storage. Irradiation did not adversely affect blueberry and cherry shelf-life. MB fumigation did not impact blueberry and cherry quality attributes initially; however, fumigated fruit exhibited greater damage and mold growth than the control and irradiated samples during storage. Irradiation at 400 Gy resulted in a ∼1 log CFU g(-1) reduction in Salmonella spp. and Listeria monocytogenes counts, indicating that this treatment cannot significantly enhance safety. CONCLUSION: This study indicates that irradiation at a target dose of 0.4 kGy for phytosanitary treatment does not negatively impact blueberry and cherry quality and can serve as an alternative to methyl bromide fumigation. © 2016 Society of Chemical Industry.

Low-dose irradiation can be used as a phytosanitary treatment for fresh table grapes.

Grapes (Vitis vinifera var. Sugraone and Vitis labrusca var. Crimson Seedless) were treated with 400, 600, and 800 Gy and the effects on physicochemical factors were measured alongside sensory testing during 3 wk of storage. Significant changes in texture and color with irradiation and age were measured but little visual difference was seen between control and irradiated grapes. However, age had a greater effect on firmness than irradiation for Sugraone grapes. Irradiation did not significantly (P ≤ 0.05) affect the SSC/TA ratio, which increased during storage. The trained panel detected significant changes in the berry texture and rachis color but rated sweetness and flavor significantly higher (P ≤ 0.05) for irradiated Sugraone as compared to the control. Consumers liked both the untreated and 800 Gy treated Sugraone grapes, but liked the untreated grapes more for texture (P ≤ 0.05). However, there was no difference in liking between irradiated (600 Gy or 800 Gy) and control samples of Crimson Seedless for any attribute. The results show that there are varietal differences in response to irradiation but the overall maintenance in quality of irradiated grapes during 3 wk of storage indicates that irradiation can serve as a viable phytosanitary treatment.

The effect of gamma irradiation as a phytosanitary treatment on physicochemical and sensory properties of bartlett pears.

A major concern in exporting agricultural commodities is the introduction or spread of exotic quarantine pests to the new area. To prevent spread of insect pests, various phytosanitary measures are used. Worldwide commercial use of irradiation as a phytosanitary treatment has increased greatly in recent years; however, trade has been limited to tropical fruits. Bartlett pear is a major summer variety of California pears with great potential and market for export. In this study, the effect of gamma irradiation at dose levels of 400, 600, and 800 Gy on physicochemical properties and sensory attributes of early and late harvest Bartlett pears was investigated. Firmness and color changes indicate that irradiation delayed the ripening of pears by 1 d. For the early harvest pears, scarring, bruising, and off flavor were significantly increased at the highest irradiation dose (800 Gy). The appearance of early harvest 800 Gy irradiated pears was the only attribute that received significantly (P ≤ 0.05) lower scores than the control in consumer testing. For the late harvest pears, the 400 Gy fruit had lowest levels of scarring and bruising as rated by trained panelist but consumers did not score the control and 800 Gy fruit differently for any attribute. Titratable acidity, total soluble solids, and chroma were significantly (P ≤ 0.05) decreased and hue increased by irradiation for the early harvest pears. These results suggest that there was a difference in radiotolerance of early and late harvest pears, but in both cases, irradiation at 400 to 600 Gy seemed to maintain best quality.

High volumes of resistance exercise are not required for greater bone mineral density during growth.

PURPOSE: The purpose of this study was to determine the minimum amount of resistance exercise that would stimulate bone formation, via an elevation in bone mineral density (BMD), during the growth period in male rats. METHODS: Forty male rats were randomly divided into control group (Con, n = 8), one ladder climb resistance-trained group (1LC, n = 8), two ladder climb resistance-trained group (2LC, n = 8), three ladder climb resistance-trained group (3LC, n = 8), and four ladder climb resistance-trained group (4LC, n = 8). All exercised groups were conditioned to climb a vertical ladder with weights appended to their tail 3 d·wk(-1) for a total of 6 wk. RESULTS: After 6 wk, left tibia BMD (mean ± SE) was significantly greater for 2LC, 3LC, and 4LC (0.233 ± 0.003 g·cm(-2)) when compared with Con (0.218 ± 0.003 g·cm). Left femur BMD was significantly greater for 2LC, 3LC, and 4LC (0.318 ± 0.003 g·cm(-2)) when compared with 1LC (0.299 ± 0.008 g·cm(-2)) and Con (0.289 ± 0.010 g·cm(-2)).There were no significant differences in BMD between 2LC, 3LC, and 4LC groups. CONCLUSION: The results suggest that during growth, a low amount of resistance exercise was just as effective as high volumes of strength training for stimulating bone modeling.

Effect of irradiation on Salmonella survival and quality of 2 varieties of whole green onions.

Two varieties of green onions, Banner and Baja Verde, were inoculated with a cocktail of 3 Salmonella strains using dip and spot inoculation and irradiated at 0, 0.3, 0.6, 0.9, and 1.2 kGy using electron beam. Salmonella survivors were enumerated using a XLD underlay/TSAYE overlay plating method. The D values were in the range of 0.26 to 0.32 kGy depending on variety but not on the method of inoculation. This indicated that a 5-log reduction of Salmonella can be achieved at a dose of 1.6 kGy. For the quality study, both varieties of green onions were irradiated at 0, 1.5, 2.0, and 2.5 kGy and evaluated for changes in microbial counts, color, texture, and visual quality during storage at 4 °C. Irradiation reduced total plate counts and psychrotrophs by 3 logs. Although the counts increased during storage, they did not exceed the initial counts of control. No significant difference was observed in color and texture between irradiated samples and control. The control maintained good visual quality for about 13 d as compared to 15 d for 1.5 and 2.5 kGy samples. The 2.0 kGy samples maintained good visual quality for 17 d suggesting that irradiation can increase shelf life by reducing spoilage microorganisms but higher doses can be detrimental to quality. At the dose levels required to achieve a 5-log reduction in Salmonella, the shelf life of whole green onion can be extended. This study shows that irradiation can be used to enhance safety without adverse effects on quality.

Irradiation D values of Salmonella spp. in diced tomatoes dipped in 1% calcium chloride.

Outbreaks of salmonellosis have been associated with eating raw domestic tomatoes. In this study, we examined the efficiency of combined irradiation and a 1% calcium chloride dip to reduce the population of Salmonella enterica strains on diced tomatoes. Tomatoes were contaminated with nalidixic acid-resistant strains of S. Hartford, S. Montevideo, or a mixture of 5 strains (S. Hartford, S. Montevideo, S. Poona, S. Michigan, S. Gaminara). We irradiated tomatoes at various doses up to 0.9 kGy from an electron beam source to conduct a D-value study (decimal reduction time required to eliminate 90% of the organism). Surviving Salmonella populations were detected by standard and recovery plating methods. D-value results ranged from 0.26 to 0.39 kGy, indicating that a 5 log(10) CFU/g reduction in Salmonella spp. in diced tomatoes would require a dose of 1.3-1.95 kGy.

1% calcium chloride treatment in combination with gamma irradiation improves microbial and physicochemical properties of diced tomatoes.

The purpose of this study was to determine the effect of a combination of a 1% calcium chloride dip with low dose irradiation on microbial populations, and biochemical and physical properties, of fresh diced tomatoes during a two-week storage period. Vine tomatoes at the light-red stage (trial 1) and Celebrity tomatoes at the table ripe stage (trial 2) were diced, dipped in 1% CaCl(2), and irradiated at 1 kGy from a Co(60) source. Tomatoes were also contaminated with cocktail of nalidixic-acid resistant Salmonella strains (S. Poona, S. Hartford, S. Gaminara, S. Michigan, and S. Montevideo) and subjected to gamma irradiation. Calcium treatment alone stimulated ethylene production in the diced tomatoes, whereas irradiation treatment alone suppressed ethylene production. The combination of calcium and irradiation treatments resulted in no change in ethylene production compared to the nontreated control, but respiration rate was suppressed by both irradiation and calcium treatment. The calcium dip was found to limit irradiation-induced loss of firmness. Irradiation, by itself and in combination with calcium treatment, resulted in a >3 log CFU/g decrease in total aerobic counts and psychrotrophs. Additionally, irradiation at 1.5 kGy eliminated > 3 log CFU/g of Salmonella organisms from tomatoes contaminated with Salmonella. Counts continued to decrease to an undetectable level over the 11 day storage period. The results indicate that the combination of calcium treatment and irradiation can reduce the risk of disease due to pathogenic organisms such as Salmonella and can eliminate the problem of softening induced by irradiation.

Irradiation and chlorination effectively reduces Escherichia coli O157:H7 inoculated on cilantro (Coriandrum sativum) without negatively affecting quality.

Cilantro (Coriandrum sativum) inoculated with Escherichia coli O157:H7 at levels approximating 10(7) CFU/g was dipped in 200 ppm chlorine solution followed by low-dose gamma irradiation. Samples were plated on tryptic soy agar containing 50 microg/ml nalidixic acid (TSAN) as well as TSAN plates with two 7-ml layers of basal yeast extract agar (TSAN-TAL). Levels of E. coli O157:H7 recovered from both types of media were determined over 11 days. Chlorination alone reduced counts by just over 1.0 log cycle, whereas irradiation at 1.05 kGy resulted in a 6.7-log reduction, and a combination of irradiation and chlorination reduced counts more than 7 log cycles. Trained panels performed analytical sensory tests at time intervals for 14 days to detect changes in yellowing, tip burn, browning, black rot, sliminess, off-aroma, and off-flavor. Sensory tests found no significant differences among attributes over time or dose in samples irradiated at 1.08 to 3.85 kGy. This study showed that combination treatments of chlorination and low-dose irradiation can significantly reduce levels of E. coli O157:H7 in fresh cilantro while maintaining product quality.