Effect of harvest-to-cooling delay and precooling on Kufri Jyoti (Solanum tuberosum) potato quality

Precooling is the rapid removal of field heat in harvested crops to preserve their quality and increase their shelf life. The following study was conducted to understand the importance of precooling and to optimize the precooling condition to extend the storage life of potatoes. Therefore, the study was divided into two components. In the first part, the Kufri Jyoti potatoes were subjected to field heat for 0-64 h, then were precooled for 48 h before sending to cold storage for 60 days. The results demonstrated that when the time delay was doubled, starch content (SC) decreased by 15.86%, reducing sugar content (RSC) increased by 32.71%, ascorbic acid content (AAC) decreased by 5.94% and total plate count (TPC) increased by 20.06%. Microstructural changes in potatoes due to the exposure to field heat were visible in SEM images. These results suggested a decrease in the quality of potatoes with an increase in time delay between harvest and cooling. In the second part of the study, the potatoes were precooled for 48 h at different temperatures (T) (6 °C, 8 °C, and 10 °C) and relative humidity (RH) (87%, 91%, and 95%), and their effect was studied on the same quality parameters after storage. Regression models were developed for each response, and models with non-significant lack of fit were selected for optimization. The analysis of the observations has shown that precooling aided in better quality retention of potatoes during cold storage.

Cold shock precooling improves the firmness of chili pepper during postharvest storage and the molecular mechanisms related to pectin

This research was conducted to explore the influence of cold shock on the firmness, a quality marker in chili pepper during 0-21 d storage and determine mechanism by cold shock impacted pectin. Chili peppers were exposed to cold shock precooling (0 ± 2 °C water/ice mixture) for 0-, 30-, 90- and 150-min, respectively. Results showed that cold shock alleviated loss of firmness throughout storage. Firmness was positively associated with sodium carbonate-soluble pectin content (r = 0.44), methylation degree of CDTA-soluble pectin (r = 0.82) and water-soluble pectin (WSP, r = 0.87), but negatively associated with WSP content (r = -0.76), and the activities of β-galactosidase (r = -0.72) and pectinlyase (r = -0.74). Cold shock for 90 min was determined to be optimal. This study confirms the applicability of cold shock precooling to maintain firmness and thereby to extend the shelf life of chili pepper.

Ice Ingestion Maintains Cognitive Performance during a Repeated Sprint Performance in The Heat

This study investigated the effects of precooling via crushed ice ingestion on cognitive performance during repeated-sprint cycling in the heat. Nine males, non-heat acclimatised to heat (mean age: 28.2 ± 2.7 y; height: 175.7 ± 9.7 cm; body-mass: 76.9 ± 10.6 kg) completed a 30 min bout of repeated-sprint (36 × 4 s sprints, interspersed with 56 s rest-breaks) on a cycle ergometer in a climate chamber (35°C, 70% relative humidity). Crushed ice ingestion (7g·kg^-1, -0.4°C, ICE) or no cooling (CON) interventions were completed at rest, in the climate chamber, 30 min prior to exercise. Working memory was assessed via the serial seven test (S7) and the automated operation span task (OSPAN) at various time points before, during, and post-exercise. Core body temperature (T_c), forehead temperature (T_h), and thermal sensation (TS) were assessed throughout the protocol. Working memory significantly declined during exercise in CON as measured by S7 (p = 0.01) and OSPAN (p = 0.03); however, it was preserved in ICE with no change at the end of exercise in either S7 or OSPAN scores compared to baseline (p = 0.50, p = 0.09, respectively). Following precooling, T_h (-0.59°C, p < 0.001) and T_c (-0.67°C, p = 0.005) were significantly decreased in ICE compared to CON. At the end of the exercise, ICE significantly reduced T_c compared to CON (p = 0.03), but no significant differences were recorded for T_h. Further, TS was lower following precooling in ICE (p = 0.008) but not during exercise. In conclusion, ice ingestion significantly reduced T_h and T_c and facilitated maintenance of cognitive performance during repeated-sprint exercise in the heat, which may lead to better decision making.

Improvements in chitosan-based slurry ice production and its application in precooling and storage of Pampus argenteus

The effects of microbubbles in chitosan-based slurry ice production were investigated, and the efficiency of chitosan-based slurry ice was evaluated for silver pomfret (Pampus argenteus) precooling and storage at 0 °C. Microbubbles generated though agitation accelerated slurry ice production by promoting ice nucleation and eliminating supercooling. Higher bubble counts improved freezing, but overly large bubbles reduced the performance. The rheological properties of chitosan solutions were also investigaed, and solutions with higher viscosity formed more bubbles. Experiments investigating precooling rates, microbial concentrations, pH, thiobarbituric-acid-reactive substances, and total volatile basic nitrogen all confirmed that chitosan-based slurry ice had higher performance than flake ice or conventional slurry ice. Chitosan-based slurry ice can be used for precooling in the fish industry to reduce energy consumption, accelerate precooling, reduce microbial growth, and improve shelf life.

Effect of precooling on pain during local anesthesia administration in children: a systematic review

This study was conducted to determine how precooling reduces the subjective reported pain and objective pain and to evaluate the effectiveness of precooling the injection site before administration of local anesthesia in children. Electronic databases (PubMed, Ovid SP, Cochrane Central Register of Controlled Trials) were searched for publications from 1980 to 2020. Studies were screened for titles and abstracts, followed by full-text evaluation of included reports. Six studies were included in this systematic review. The primary outcome evaluated was the pain perception or the subjective pain reported by the child receiving the injection. The secondary outcome evaluated was objective pain evaluated in each study. Among 5 studies that evaluated child reported pain scores on a visual analogue scale (VAS), 4 studies reported lower scores in the precooling group and one study reported a higher VAS score in the precooling group than in children treated with 20% benzocaine topical anesthesia. Among 6 studies that evaluated the pain reaction of children by Sound Eye Motor (SEM) score, 4 studies reported a lower SEM score in the precooling group, one study reported no significant difference between the precooling and control groups, and one study reported higher SEM scores in the precooling group than in children treated with 20% benzocaine topical anesthesia. Within the limits of this systematic review, evidence suggests that precooling the injection site with ice can be an effective adjunct to topical anesthesia in reducing both subjective and objective pain during local anesthesia administration in children.

Effects of skin surface cooling before exercise on lactate accumulation in cool environment

PURPOSE

We assessed whether plasma lactate accumulation increased and the lactate threshold (LT) declined when the skin temperature was lowered by whole body skin surface cooling before exercise in cool, but not temperate, conditions, and whether the lowered LT was associated with sympathetic activation or lowered plasma volume (PV) by cold-induced diuresis.

METHODS

Ten healthy subjects performed a graded maximal cycling exercise after pre-conditioning under three different conditions for 60 min. Ambient temperature (using an artificial climatic chamber) and water temperature in a water-perfusion suit controlled at 25 and 34 °C in temperate-neutral (Temp-Neut); 25 and 10 °C in temperate-cool (Temp-Cool); and at 10 and 10 °C in cool-cool (Cool-Cool) conditions, respectively. Esophageal (T_es) and skin temperatures were measured; plasma lactate ([Lac]_p) and noradrenaline concentrations ([Norad]_p), and relative change in PV (%ΔPV) were determined before and after pre-conditioning and during exercise, and LT was determined.

RESULTS

After pre-conditioning, T_es was not different among trials, whereas the mean skin temperature was lower in Cool-Cool and Temp-Cool than in Temp-Neut (P < 0.001). During exercise, [Lac]_p and [Norad]_p were higher (P = 0.009 and P < 0.001, respectively) and LT was lower (P = 0.013) in Cool-Cool than in the other trials. The %ΔPV was not different among trials. LT was correlated with [Norad]_p during exercise (R = 0.50, P = 0.005).

CONCLUSIONS

Whole body skin surface cooling before exercise increases lactate accumulation and decreases LT with sympathetic activation when exercise is performed in a cool, but not in a temperate, environment.

Whole body precooling attenuates the extracellular HSP72, IL-6 and IL-10 responses after an acute bout of running in the heat

The impact of whole-body precooling on the extracellular heat shock protein 72 (eHSP72) and cytokine responses to running in the heat is undefined. The aim of this study was to determine whether precooling would attenuate post-exercise eHSP72 and cytokine responses. Eight male recreational runners completed two 90-minute bouts of running at 65% [Formula: see text]O₂max in 32 ± 0.9°C and 47 ± 6 % relative humidity (RH) preceded by either 60-minutes of precooling in 20.3 ± 0.3°C water (COOL) or 60 min rest in an air-conditioned laboratory (20.2 ± 1.7°C, 60 ± 3% RH; CON). eHSP72, TNF-α, IL-6, IL-10 IL-1ra were determined before and immediately after exercise. The elevation in post-exercise eHSP72 was attenuated after COOL (+0.04 ± 0.10 ng.mL^-1) compared to CON (+ 0.29 ± 0.26 ng.mL^-1;P < 0.001). No changes in TNF-α were observed at any stage. COOL reduced the absolute post-exercise change in IL-6 (P = 0.011) and IL-10 (P = 0.03) compared to CON. IL-1ra followed this trend (P = 0.063). A precooling-induced attenuation of eHSP72 and proinflammatory cytokines may aid recovery during multi-day sporting events, but could be counterproductive if a training response or adaptation to environmental stress is a desired outcome.

Effect of the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment

It has been demonstrated that precooling with ice slurry ingestion enhances endurance exercise capacity in the heat. However, no studies have yet evaluated the optimal timing of ice slurry ingestion for precooling. This study aimed to investigate the effects of varying the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment. Ten active male participants completed 3 experimental cycling trials to exhaustion at 55% peak power output (PPO) after 15min of warm-up at 30% PPO at 30°C and 80% relative humidity. Three experimental conditions were set: no ice slurry ingestion (CON), pre-warm-up ice slurry ingestion (-1°C; 7.5gkg^-1) (PRE), and post-warm-up ice slurry ingestion (POST). Rectal and mean skin temperatures at the beginning of exercise in the POST condition (37.1±0.2°C, 33.8±0.9°C, respectively) were lower than those in the CON (37.5±0.3°C; P<0.001, 34.8±0.8°C; P<0.01, respectively) and PRE (37.4±0.2°C; P<0.01, 34.6±0.7°C; P<0.01, respectively) conditions. These reductions increased heat storage capacity and resulted in improved exercise capacity in the POST condition (60.2±8.7min) compared to that in the CON (52.0±11.9min; effect size [ES]=0.78) and PRE (56.9±10.4min; ES=0.34) conditions. Ice slurry ingestion after warm-up effectively reduced both rectal and skin temperatures and increased cycling time to exhaustion in a warm environment. Timing ice slurry ingestion to occur after warm-up may be effective for precooling in a warm environment.

Effect of Preheating and Precooling on the Flexural Strength and Modulus of Elasticity of Nanohybrid and Silorane-based Composite

STATEMENT OF THE PROBLEM

Composite resin may be used in different temperatures; it is crucial to determine the effect of temperature on mechanical properties of nanohybrid and silorane-based composite.

PURPOSE

This in vitro study compared the flexural strength and modulus of elasticity of nanohybrid and silorane-based resin composite, at 4˚C, room temperature (25˚C), and 45˚C.

MATERIALS AND METHOD

In this experimental study, 60 specimens were prepared in a metal split mold (2×2×25mm). Two different resin composites, Filtek Z250 XT (3M/ ESPE) and Filtek P90 (3M/ESPE), were evaluated. The material were inserted into split molds at room temperature, 4˚C or 45˚C and cured with LED (1200 mW/cm(2)) for 20 seconds in four points (n=10). Then, a three-point bending test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min for measuring the flexural strength and flexural modulus of samples. The data were analyzed by the two-way ANOVA and Tukey test (p< 0.05).

RESULTS

The mean highest flexural strength was observed at 45˚C, showing statistically significant difference with flexural strength at 4˚C (p= 0.0001) and 25˚C (p= 0.003) regardless of the type of resin composite. The flexural modulus at 45˚C was highest, showing the statistically significant difference with flexural modulus at 4˚C (p= 0.0001) and 25˚C (p= 0.002). The flexural modulus was statistically different between nanohybrid and silorane-based resin composite (p= 0.01) in 25˚C and 45˚C, but there were no statistically significant differences between flexural strength of Filtek Z250 XT and Filtek P90 regardless of the temperatures (p= 0.062).

CONCLUSION

Preheating the resin composite at 45˚C improves flexural strength and modulus of nanohybrid and silorane-based resin composite. However, flexural strength and modulus of the tested materials were not affected by precooling. The flexural modulus of nanohybrid resin composite was significantly higher than silorane-based resin composite in 25˚C and 45˚C temperatures.

A simplified heat transfer model for predicting temperature change inside food package kept in cold room

A simple analytical heat flow model for a closed rectangular food package containing fruits or vegetables is proposed for predicting time temperature distribution during transient cooling in a controlled environment cold room. It is based on the assumption of only conductive heat transfer inside a closed food package with effective thermal properties, and convective and radiative heat transfer at the outside of the package. The effective thermal conductivity of the food package is determined by evaluating its effective thermal resistance to heat conduction in the packages. Food packages both as an infinite slab and a finite slab have been investigated. The finite slab solution has been obtained as the product of three infinite slab solutions describe in ASHRAE guide and data book. Time temperature variation has been determined and is presented graphically. The cooling rate and the half cooling time were also obtained. These predicted values, are compared with the experimentally measured values for both the finite and infinite closed packages containing oranges. An excellent agreement between them validated the simple proposed model.