Scanning Electron Microscopy Structure and Firmness of Papain Treated Apple Slices

\u27Mcintosh\u27 apple (Malus domesrica Borkh.) slices were treated with papain. Textural changes were recorded with an Instron Universal Testing Machine. Structural changes and distribution of microorganisms in apple tissues after treatment were observed with a scanning electron microscope (SEM). Apple slices submerg ed in a 1% papain solution were significantly firmer than apple slices submerged in the distilled water control for a 24 hour period (P \u3c 0.05). Three and four days after slicing , a significantly smaller decay index was observed on the apple slices submerged in papain solution than on the control slices. Under SEM, less severe cell wall breakdown was observed on the apple tissues treated with papain than on apple tissues without treatment. Less spores were also observed on the papain treated apple slices than apple slices without treatment. Apple tissues treated with papain solution and distilled water also demonstrated noticeable st ru ctural differences. The apple tissues treated with papain solution for 18 hours retained the original cell structure while the cells in the apple tissues treated with distilled water collapsed

Mechanical Properties of Rock With Intersection Structures and its Progressive Failure Mechanism

To investigate the influence of intersection structures on the mechanical properties and failure mechanisms of rock materials, a series of uniaxial compression tests on complete red sandstone specimens and specimens with various hole shapes (T-shape, cross-shape, and shaft-roadway-shape) were conducted by the Instron 1346 servo-controlled rock mechanics testing machine. Flac3D software and digital image correlation (DIC) were used to simulate the internal stress distribution of rock specimens and reproduce the process of fracture, i.e., cracks initiate, propagate, and coalesce with each other into macroscopic failure under progressive loading. The results show that the intersection structure has a signiflcant weakening effect on the mechanical properties of the rock. The rock strength, elastic modulus, and peak strain of specimens can be ranked as complete specimens > cross-shaped intersection structure specimens > T-shaped intersection structure specimens>shaft-roadway-shaped intersection structure specimens. The energy consumption ratio of the intersection structure specimens before the peak reaches more than 30%, which is approximately twice that of the intact specimens. The brittleness coefflcients of the four types of specimens are 0.18, 0.26, 0.21, and 0.20, respectively. The intersection structure specimens induced different degrees of tensile and compressive stress concentration zones on the top and bottom sides of the intersection center point. As a result, initial tensile cracks parallel to the loading direction and shear cracks leading to spalling failure on both sides of the holes were formed. With the increase of the axial stress, secondary tensile cracks extending on the opposite direction appeared at the upper and lower corners of the hole. When the far-fleld cracks that propagated along the diagonal line coalesced with secondary tensile cracks, macro shear-failure of the specimens appeared. With the increase in axial stress, the principal strain monitored during the fracture process of the specimens gradually increased, then it slowly decreased after the peak. The arched boundary of the T-shaped intersection structure specimen had good stability because of its advantage of suppressing the occurrence of the spalling failure. The shaft-roadway-shaped intersection structure could provide compensation space for the secondary tensile cracks due to the existence of the vertical well. The degree of inhibition of initial tensile cracks was so small that the type of specimens was highly prone to instability or failure.National Key Research and Development Program of China during the Thirteenth Five Year Plan Period: The Continuous Mining Theory and Technology on Spatiotemporal Synergism of Multi-mining Areas within a Large Ore Block for Deep Metal Deposit [2017YFC0602901]; Fundamental Research Funds for the Central Universities of Central South University [2018zzts215]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

SQ-Swin: a Pretrained Siamese Quadratic Swin Transformer for Lettuce Browning Prediction

Packaged fresh-cut lettuce is widely consumed as a major component of vegetable salad owing to its high nutrition, freshness, and convenience. However, enzymatic browning discoloration on lettuce cut edges significantly reduces product quality and shelf life. While there are many research and breeding efforts underway to minimize browning, the progress is hindered by the lack of a rapid and reliable methodology to evaluate browning. Current methods to identify and quantify browning are either too subjective, labor intensive, or inaccurate. In this paper, we report a deep learning model for lettuce browning prediction. To the best of our knowledge, it is the first-of-its-kind on deep learning for lettuce browning prediction using a pretrained Siamese Quadratic Swin (SQ-Swin) transformer with several highlights. First, our model includes quadratic features in the transformer model which is more powerful to incorporate real-world representations than the linear transformer. Second, a multi-scale training strategy is proposed to augment the data and explore more of the inherent self-similarity of the lettuce images. Third, the proposed model uses a siamese architecture which learns the inter-relations among the limited training samples. Fourth, the model is pretrained on the ImageNet and then trained with the reptile meta-learning algorithm to learn higher-order gradients than a regular one. Experiment results on the fresh-cut lettuce datasets show that the proposed SQ-Swin outperforms the traditional methods and other deep learning-based backbones

A Mathematical Model for Pathogen Cross-Contamination Dynamics During Produce Wash

One of the main challenges for the fresh-food produce industry is to ensure that the produce is free from harmful pathogens. A potential area of risk is due to cross-contamination in a sanitizing chlorine wash-cycle, where the same water is used to wash contaminated as well as non-contaminated produce. However, this is also an area where effective intervention strategies are possible, provided we have a good understanding of the mechanism of cross-contamination. Based on recent experimental work by Luo, Y. et al. A pilot plant scale evaluation of a new process aid for enhancing chlorine efficacy against pathogen survival and cross-contamination during produce wash, International Journal of Food Microbiology, 158 (2012), 133–139, we have built mathematical models that allow us to quantify the amount of cross-contamination of Escherichia coli O157:H7 from spinach to lettuce, and assessed the efficacy of the associated wash-cycle protocols

The use of redox potential to estimate free chlorine in fresh produce washing operations : possibilities and limitations

Maintaining free chlorine (FC) residual at appropriate pH values is a control approach used to prevent pathogen cross-contamination during tomato dump tank handling and fresh-cut produce washing operations. Oxidation reduction potential (ORP) is a rapid measurement of oxidant-based sanitizer strength, and has been used to estimate FC residual. However, factors, in addition to FC and pH, which influence ORP are not fully understood. This study examined the relationship between ORP and FC under chlorine demand (CLD) free conditions and during fresh produce washing. An equation predictive of FC was developed in the form logFC = f(ORP, ORP2, ORP.pH). A good correlation between ORP and logFC was maintained when other variables changed, but the resulting ORP-logFC curve changed (slope, intercept). A decrease in pH or temperature led to an increase in ORP. Using tap water to wash the produce instead of distilled water significantly changed the ORP. For different types of tested produce, i.e., fresh-cut carrot, onion, romaine and iceberg lettuce, and for whole tomatoes, increasing the product-to-water ratio (i.e., increasing the organics transferred into the water) led to a decrease in ORP for a specific FC residual. The choice of acidulant during washing also influenced ORP. Overall, the correlation of ORP with logFC is more reliable at the lower end (5 mg/L FC) than at the higher end (100 mg/L FC) of the FC range used in fresh produce washing. However, since the ORP in fresh produce wash water is affected significantly in multiple ways by the wash water and process conditions, the predicted FC values with ORP under certain fresh-cut produce washing conditions cannot be generalized for other conditions

Survival of Salmonella enterica and shifts in the culturable mesophilic aerobic bacterial community as impacted by tomato wash water particulate size and chlorine treatment

Particulates of harvest debris are common in tomato packinghouse dump tanks, but their role in food safety is unclear. In this study we investigated the survival of Salmonella enterica and the shifts in relative abundance of culturable mesophilic aerobic bacteria (cMAB) as impacted by particulate size and interaction with chlorine treatment. Particulates suspended in grape tomato wash water spanned a wide size range, but the largest contribution came from particles of 3–20 μm. Filtration of wash water through 330 μm, applied after 100 mg/L free chlorine (FC) wash, reduced surviving cMAB by 98%. The combination of filtration (at 330 μm or smaller pore sizes) and chlorinated wash also altered the cMAB community, with the survivors shifting toward Gram-positive and spore producers (in both lab-simulated and industrial conditions). When tomatoes and harvest debris inoculated with differentially tagged Salmonella were washed in 100 mg/L FC for 1 min followed by filtration, only cells originating from harvest debris survived, with 85 and 93% of the surviving cells associated with particulates larger than 330 and 63 μm, respectively. This suggests that particulates suspended in wash water can protect Salmonella cells from chlorine action, and serve as a vector for cross-contamination

Towards Online Multiresolution Community Detection in Large-Scale Networks

The investigation of community structure in networks has aroused great interest in multiple disciplines. One of the challenges is to find local communities from a starting vertex in a network without global information about the entire network. Many existing methods tend to be accurate depending on a priori assumptions of network properties and predefined parameters. In this paper, we introduce a new quality function of local community and present a fast local expansion algorithm for uncovering communities in large-scale networks. The proposed algorithm can detect multiresolution community from a source vertex or communities covering the whole network. Experimental results show that the proposed algorithm is efficient and well-behaved in both real-world and synthetic networks

Cross-cutting concepts to transform agricultural research

Agriculture is an important link to many issues that challenge society today, including adaptation to and mitigation of climate change, food security, and communicable and non-communicable diseases in animals and humans. Transformation of agriculture and food systems has become a priority for a range of federal agencies and global organizations. It is imperative that food and agricultural researchers effectively harness the global convergence of priorities to overcome research “silos” through deep and sustained systemic change. Herein, we identify intersections in federal and global initiatives encompassing climate adaptation and mitigation; human health and nutrition; animal health and welfare; food safety and security; and equity and inclusion. Many agencies and organizations share these priorities, but efforts to address them remain uncoordinated and opportunities for collaboration untapped. Based on the interconnectedness of the identified priority areas, we present a research framework to catalyze agricultural transformation, beginning with the research enterprise. We propose that transformation in agricultural research should incorporate (1) innovation, (2) integration, (3) implementation, and (4) evaluation. This framework provides approaches for food and agricultural research to contribute to sustainable, flexible, and coordinated transformation in the agricultural sector

Carboxymethyl cellulose capped zinc oxide nanoparticles dispersed in ionic liquid and its antimicrobial effects against foodborne pathogens

Zinc oxide nanoparticles (ZnO NPs) have been proven with antimicrobial function, but the high tendency to aggregate hinders their practical applications. To improve the dispersibility of ZnO NPs as antimicrobial agent, choline acetate (ChAc), a class of ionic liquids, was employed to facilitate the dispersion of ZnO NPs capped with carboxymethyl cellulose (CMC). In this study, ZnO-CMC NPs at various concentrations were added in DI water with or without ChAc followed by sonication. Uniform and small particles were observed in ChAc-dispersed ZnO-CMC (ChAc/ZnO-CMC) by atomic force microscopy and transmission electron microscopy, due to the formation of a double layer on their surface via the positive and negative charged ionic clusters from ChAc, thereby enhancing repulsion and inhibiting aggregation. The antimicrobial capacity was tested against two strains - Listeria monocytogenes (L. monocytogenes) and Escherichia coli K-12 (E. coli K-12), based on minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bacteria growth kinetics. The ChAc/ZnO-CMC exhibited the strongest antimicrobial activities as compared with commercial ZnO and as-prepared ZnO-CMC without ChAc. The antimicrobial capacity was related to occurrence of cytolysis, disruption of cell walls and ROS production. Overall, ChAc/ZnO-CMC NPs hold great potential as an antimicrobial agent and may be incorporated into different food packaging films and coatings