RADIO FREQUENCY‐HOT WATER DIPS FOR POSTHARVEST CODLING MOTH CONTROL IN APPLES*

A combination radio frequency‐hot water dip method was examined as a potential quarantine treatment against fifth instars of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apples, Malus sylvestris (L.) var. domestica (Borkh.) Mansf., which were intended for export to Japan. The apples were initially exposed to 27.12‐MHz radio frequency energy at 12 kW for 2.75 min and were then submerged in a range of hot water dips (48–50C) for different durations. Efficacious tests were at 48C for >2 h, at 49C for >50 min and at 50C for >40 min. Fruit quality tests indicated that the best hot water parameters were at 50C for 40 min. Fruit quality after 2 weeks was cultivar dependent where “Fuji” apples tolerated heat treatment better than “Delicious” and “Gala” apples. None of the treated fruits were acceptable after 60 days. Regardless of cultivar, heat treatment resulted in loss of both peel and fresh colors, coupled with reduced firmness and increased external and internal damage.     

USING CAPACITIVE (RADIO FREQUENCY) DIELECTRIC HEATING IN FOOD PROCESSING AND PRESERVATION – A REVIEW

Capacitive (Radio Frequency) dielectric heating has great potential for achieving rapid and uniform heating patterns in foods, providing safe, high quality food products. This review describes and discusses the major technology behind capacitive (RF) dielectric heating in food processing and preservation, the current applications of the technology in the industry, the potential use of mathematical modeling for heating system design, and the major challenges facing the use of this technology in food processing. A vast amount of work is still necessary to further understand the dielectric properties of both food and packaging materials in order to refine system design and maximize performance of this technology in the field of packaged food products. Various economic studies will also play an important role in understanding the overall cost and viability of commercial application of this technology in food processing.     

RADIO FREQUENCY (RF) HEATING OF STARCH SOLUTIONS UNDER CONTINUOUS FLOW CONDITIONS: EFFECT OF SYSTEM AND PRODUCT PARAMETERS ON TEMPERATURE CHANGE ACROSS THE APPLICATOR TUBE

Studies were conducted to evaluate the effect of system and product parameters on the temperature change (ΔT) across a 1.5 kW radio frequency heater operating at 27.12 MHz. Starch solutions (1 to 4% w/w) were used at three different flow rates (0.35, 0.5 and 1 L/min) and four power levels (672, 912, 1152 and 1392 W). The average heating rate of starch solutions varied from 6 to 19C/min depending on flow rate, concentration and power level. The corresponding residence time varied from 1.5 to 4.3 min. Central composite designs involving power (830 to 1234 W) and starch concentration (1 to 4% w/w) at 0.5 L/min were used to study the effects of salt, pH and sugar. As expected fluid flow rate, power level and salt concentration had significant impact (P ± 0.05) on temperature change (ΔT) across the applicator tube. Although the interaction effect of salt and concentration influenced ΔT (P < 0.05), observed trends were not clear cut. Sugar and pH had no significant (P >0.05) influence on ΔT due probably to their relatively lower conductivities. However, the interaction effect of sugar and starch concentration affected ΔT. Correlations were developed for estimating ΔT across the tube as a function of power level, concentration, pH, added salt and sugar. Finally, dimensionless correlations involving the generalized Reynolds, Prandtl, Grashof numbers, dimensionless power and loss‐factor ratios were developed for estimating the temperature ratio (U) across the RF applicator.     

INCLUDING CHESTNUTS AND SUGAR BEET PULP IN DIETS FOR PIGS: THE EFFECTS ON THE QUALITY OF PORK MEAT AND THE SENSORY PROPERTIES OF DRY-CURED SAUSAGE (CHORIZO GALLEGO)

This research was aimed at evaluating how the inclusion of dried chestnuts and dried sugar beet pulp in diets for pigs affected the quality of pork meat and the sensory properties of dry-cured sausage ( chorizo gallego ). The meat from pigs that received a diet with chestnuts and sugar beet pulp (CBP) showed lower thiobarbituric acid values and higher water-holding capacity than meat from pigs fed a conventional diet (C). Significant differences were also observed between both batches in color parameters and fatty acid composition of the meat. In the sensory analysis of chorizo, the sausages manufactured with meat from pigs fed the CBP diet were significantly better rated than those with meat from pigs fed a C diet in appearance, odor, flavor, texture and overall score.

PRACTICAL APPLICATIONS

The inclusion of dried chestnuts and dried sugar beet pulp in diets for pigs during the fattening period allowed us to recover some of the ingredients more traditionally used in the feeding of pigs. This inclusion modifies some parameters of the resulting pork meat quality; (it decreases lipid oxidation and increases water-holding capacity and polyunsaturated fatty acid content) and also improves the sensory properties of any dry-cured product made with this pork meat.     

PREPARATORY STUDIES FOR THE IMPLEMENTATION OF NORM UNE 66020-1:2001 (OR NORM ISO 2859-1:1999) IN A CANNED MARINE FOOD FACTORY

The Spanish norm UNE 66020-1:2001 is equivalent to the international norm ISO 2859-1:1999 and deals with inspection by attributes of lots of material. In order to implement such a norm in a canned marine food factory (which manufactures mainly bluefin tuna in vegetal oil), some preliminary work was carried out. First, a careful study of the production process led to three possible sources of variation in the final weight of the cans produced, namely the canning machine, the cans used and the balance utilized for weighing. Afterward, each of these sources of variation was studied, which resulted in a value of the process average. This average shall enable the responsible authority of the company to set an acceptance quality limit, which should allow the application of the cited norm.

PRACTICAL APPLICATION

This work is expected to be considered an example of the studies that need to be carried out previously to the implementation of norm UNE 66020-1:2001 (i.e., norm ISO 2859-1:1999). Moreover, an additional point to highlight is the fact that this work is not a simulation but rather, it was developed in a real factory, devoted to the manufacturing of canned marine food.