Effect of mild heat-shock treatments on pink discoloration and physiological parameters in fresh-cut iceberg lettuce

AbstractFresh-cut lettuce is a very well-known salad for today's routines because it obliges minimal preparation to minimize the loss of health beneficial vitamins, minerals, antioxidants and other phytochemicals. It is a prodigious challenge to serve its consumers fresh. Quality of freshly processed lettuce under high CO2 modified atmosphere packaging (MAP) has been investigated as a realistic alternative technique for its preservation. Storage under high CO2 atmospheric treatments exhibited a significant impact in microbial development, electrolyte leakage, volatile metabolites and sensory quality of fresh-cut iceberg lettuce. This storage condition (MAP 1: 5 kPa O2 and 20 kPa CO2 balanced by N2 at 7 °C for 6 days) inhibited the growth of mesophilic bacteria and yeasts; delayed the enzymatic browning (cut-edges and intact surface) of fresh-cut iceberg lettuce and overall visual quality was also in acceptance limit. The development of off-odors was perceived in high CO2 MAP as a consequence of volatiles (ethanol and acetaldehyde) accumulation which was persisted at an inexcusable level during 6 days of storage periods.

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Heat shock factor 2 is required for maintaining proteostasis against febrile-range thermal stress and polyglutamine aggregation

Molecular Biology of the Cell ◽

10.1091/mbc.e11-04-0330 ◽

2011 ◽

Vol 22 (19) ◽

pp. 3571-3583 ◽

Cited By ~ 37

Author(s):

Toyohide Shinkawa ◽

Ke Tan ◽

Mitsuaki Fujimoto ◽

Naoki Hayashida ◽

Kaoru Yamamoto ◽

...

Keyword(s):

Thermal Stress ◽

Heat Shock ◽

Protein Misfolding ◽

Reproductive Organs ◽

Heat Shock Factors ◽

Mild Heat ◽

Promising Therapeutic Target ◽

Αb Crystallin ◽

Shock Proteins ◽

Polyglutamine Protein

Heat shock response is characterized by the induction of heat shock proteins (HSPs), which facilitate protein folding, and non-HSP proteins with diverse functions, including protein degradation, and is regulated by heat shock factors (HSFs). HSF1 is a master regulator of HSP expression during heat shock in mammals, as is HSF3 in avians. HSF2 plays roles in development of the brain and reproductive organs. However, the fundamental roles of HSF2 in vertebrate cells have not been identified. Here we find that vertebrate HSF2 is activated during heat shock in the physiological range. HSF2 deficiency reduces threshold for chicken HSF3 or mouse HSF1 activation, resulting in increased HSP expression during mild heat shock. HSF2-null cells are more sensitive to sustained mild heat shock than wild-type cells, associated with the accumulation of ubiquitylated misfolded proteins. Furthermore, loss of HSF2 function increases the accumulation of aggregated polyglutamine protein and shortens the lifespan of R6/2 Huntington's disease mice, partly through αB-crystallin expression. These results identify HSF2 as a major regulator of proteostasis capacity against febrile-range thermal stress and suggest that HSF2 could be a promising therapeutic target for protein-misfolding diseases.

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Tracking an Escherichia coli O157:H7–Contaminated Batch of Leafy Greens through a Pilot-Scale Fresh-Cut Processing Line

Journal of Food Protection ◽

10.4315/0362-028x.jfp-14-058 ◽

2014 ◽

Vol 77 (9) ◽

pp. 1487-1494 ◽

Cited By ~ 11

Author(s):

ANNEMARIE L. BUCHHOLZ ◽

GORDON R. DAVIDSON ◽

BRADLEY P. MARKS ◽

EWEN C. D. TODD ◽

ELLIOT T. RYSER

Keyword(s):

Escherichia Coli ◽

Membrane Filtration ◽

Fluorescent Protein ◽

Pilot Scale ◽

Escherichia Coli O157 ◽

E Coli ◽

Leafy Greens ◽

Iceberg Lettuce ◽

Processing Line ◽

Fresh Cut

Cross-contamination of fresh-cut leafy greens with residual Escherichia coli O157:H7–contaminated product during commercial processing was likely a contributing factor in several recent multistate outbreaks. Consequently, radicchio was used as a visual marker to track the spread of the contaminated product to iceberg lettuce in a pilot-scale processing line that included a commercial shredder, step conveyor, flume tank, shaker table, and centrifugal dryer. Uninoculated iceberg lettuce (45 kg) was processed, followed by 9.1 kg of radicchio (dip inoculated to contain a four-strain, green fluorescent protein–labeled nontoxigenic E. coli O157:H7 cocktail at 106 CFU/g) and 907 kg (2,000 lb) of uninoculated iceberg lettuce. After collecting the lettuce and radicchio in about 40 bags (~22.7 kg per bag) along with water and equipment surface samples, all visible shreds of radicchio were retrieved from the bags of shredded product, the equipment, and the floor. E. coli O157:H7 populations were quantified in the lettuce, water, and equipment samples by direct plating with or without prior membrane filtration on Trypticase soy agar containing 0.6% yeast extract and 100 ppm of ampicillin. Based on triplicate experiments, the weight of radicchio in the shredded lettuce averaged 614.9 g (93.6%), 6.9 g (1.3%), 5.0 g (0.8%), and 2.8 g (0.5%) for bags 1 to 10, 11 to 20, 21 to 30, and 31 to 40, respectively, with mean E. coli O157:H7 populations of 1.7, 1.2, 1.1, and 1.1 log CFU/g in radicchio-free lettuce. After processing, more radicchio remained on the conveyor (9.8 g; P < 0.05), compared with the shredder (8.3 g), flume tank (3.5 g), and shaker table (0.1 g), with similar E. coli O157:H7 populations (P > 0.05) recovered from all equipment surfaces after processing. These findings clearly demonstrate both the potential for the continuous spread of contaminated lettuce to multiple batches of product during processing and the need for improved equipment designs that minimize the buildup of residual product during processing.

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Humoral immune response upon mild heat-shock conditions in Galleria mellonella larvae

Journal of Insect Physiology ◽

10.1016/j.jinsphys.2007.06.003 ◽

2007 ◽

Vol 53 (11) ◽

pp. 1134-1144 ◽

Cited By ~ 44

Author(s):

Iwona Wojda ◽

Teresa Jakubowicz

Keyword(s):

Immune Response ◽

Heat Shock ◽

Humoral Immune Response ◽

Galleria Mellonella ◽

Mild Heat ◽

Humoral Immune

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Repeated mild heat shock delays ageing in cultured human skin fibroblasts

IUBMB Life ◽

10.1080/15216549800203162 ◽

1998 ◽

Vol 45 (4) ◽

pp. 753-759 ◽

Cited By ~ 7

Author(s):

Suresh Rattan

Keyword(s):

Heat Shock ◽

Human Skin ◽

Skin Fibroblasts ◽

Human Skin Fibroblasts ◽

Mild Heat

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Efficacy of chlorine, peroxyacetic acid and mild-heat treatment on the reduction of natural microflora and maintenance of quality of fresh-cut calçots (Allium cepa L.)

LWT ◽

10.1016/j.lwt.2018.05.005 ◽

2018 ◽

Vol 95 ◽

pp. 339-345 ◽

Cited By ~ 3

Author(s):

Lorena Zudaire ◽

Inmaculada Viñas ◽

Maribel Abadias ◽

Joan Simó ◽

Ingrid Aguiló-Aguayo

Keyword(s):

Heat Treatment ◽

Allium Cepa ◽

Peroxyacetic Acid ◽

Mild Heat ◽

Allium Cepa L ◽

Natural Microflora ◽

Fresh Cut

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Preferential deadenylation of Hsp70 mRNA plays a key role in regulating Hsp70 expression in Drosophila melanogaster

Molecular and Cellular Biology ◽

10.1128/mcb.14.6.3646-3659.1994 ◽

1994 ◽

Vol 14 (6) ◽

pp. 3646-3659

Author(s):

R P Dellavalle ◽

R Petersen ◽

S Lindquist

Keyword(s):

Drosophila Melanogaster ◽

Heat Shock ◽

Rna Processing ◽

Hsp70 Expression ◽

Hsp70 Mrna ◽

Mild Heat ◽

Endonucleolytic Cleavage ◽

Heat Shocks ◽

Low Efficiency ◽

Hsp70 Synthesis

Following a standard heat shock, approximately 40% of Hsp70 transcripts in Drosophila melanogaster lack a poly(A) tail. Since heat shock disrupts other aspects of RNA processing, this observation suggested that heat might disrupt polyadenylation as well. We find, however, that as the temperature is increased a larger fraction of Hsp70 RNA is polyadenylated. Poly(A)-deficient Hsp70 RNAs arise not from a failure in polyadenylation but from the rapid and selective removal of poly(A) from previously adenylated transcripts. Poly(A) removal is highly regulated: poly(A) is (i) removed much more rapidly from Hsp70 RNAs than from Hsp23 RNAs, (ii) removed more rapidly after mild heat shocks than after severe heat shocks, and (iii) removed more rapidly after a severe heat shock if cells have first been conditioned by a mild heat treatment. Poly(A) seems to be removed by simple deadenylation rather than by endonucleolytic cleavage 5' of the adenylation site. During recovery from heat shock, deadenylation is rapidly followed by degradation. In cells maintained at high temperatures, however, the two processes are uncoupled and Hsp70 RNAs are deadenylated without being degraded. These deadenylated mRNAs are translated with low efficiency. Deadenylation therefore allows Hsp70 synthesis to be repressed even when degradation of the mRNA is blocked. Poly(A) tail shortening appears to play a key role in regulating Hsp70 expression.

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Combined Effect of Dipping in Oxalic or in Citric Acid and Low O2 Modified Atmosphere, to Preserve the Quality of Fresh-Cut Lettuce during Storage

Foods ◽

10.3390/foods9080988 ◽

2020 ◽

Vol 9 (8) ◽

pp. 988

Author(s):

Bernardo Pace ◽

Imperatrice Capotorto ◽

Michela Palumbo ◽

Sergio Pelosi ◽

Maria Cefola

Keyword(s):

Citric Acid ◽

Respiration Rate ◽

Modified Atmosphere Packaging ◽

Packaging Material ◽

Combined Effect ◽

Modified Atmosphere ◽

Iceberg Lettuce ◽

Fresh Cut ◽

Main Factor

Leaf edge browning is the main factor affecting fresh-cut lettuce marketability. Dipping in organic acids as well as the low O2 modified atmosphere packaging (MAP), can be used as anti-browning technologies. In the present research paper, the proper oxalic acid (OA) concentration, able to reduce respiration rate of fresh-cut iceberg lettuce, and the suitable packaging materials aimed to maintaining a low O2 during storage, were selected. Moreover, the combined effect of dipping (in OA or in citric acid) and packaging in low O2 was investigated during the storage of fresh-cut iceberg lettuce for 14 days. Results showed a significant effect of 5 mM OA on respiration rate delay. In addition, polypropylene/polyamide (PP/PA) was select as the most suitable packaging material to be used in low O2 MAP. Combining OA dipping with low O2 MAP using PP/PA as material, resulted able to reduce leaf edge browning, respiration rate, weight loss and electrolyte leakage, preserving the visual quality of fresh-cut lettuce until 8 days at 8 °C.

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