Pilot System for Process-Ready Brined Cucumbers

Pickling Cucumber Improvement Committee Meeting Abstract

Henry P. Fleming and Ervin G. Humphries

North Carolina State University

Procedures for the preservation of pickling cucumbers by brining have changed significantly over the past 50 years due to increasing environmental concerns with disposal of salt and organic wastes and demands for higher, more uniform quality of the brined products. However, waste control remains a serious concern for many companies, and demands for higher product quality and uniformity are increasing in the competitive food industry. The objective of the current project is to develop a palletized system for temporarily storing “process-ready” brined cucumbers. It is intended that the system be applicable for use by growers and/or processors of brined cucumbers and certain other vegetables. Potential advantages of the system to growers include: (1) an increase in marketing flexibility, and (2) value addition. Potential advantages to processors include: (1) elimination or significant reduction in salt and organic wastes, and (2) improved quality and uniformity of brined cucumbers.

Procedure. Cucumbers graded to size are washed, blanched, and cooled (optional for non-fermented) and aseptically transferred to the bag-in-box fermentation/storage container, along with brine and starter culture (if to be fermented) or sulfite (if to be non-fermented). The bag is filled and heat-sealed, and the container then stored until needed for processing.

Equipment. The washer consists of a bank of six high pressure flood nozzles, maintained at 90 psi for the initial four nozzles, through which recycled washwater is sprayed, and at 40 psi for the final two nozzles, through which fresh water is sprayed. The blancher is a ferris wheel type with ten sections that forcibly submerge cucumbers under the blanching water. Water temperature is held at ca. 178EF, and blanching time can be varied between 18 and 200 seconds. The cooling and transfer conveyor functions by circulating potable water through a reservoir of crushed ice and onto the blanched cucumbers as they are being transferred to the bag-in-box. The cucumbers are cooled sufficiently to equilibrate with the brine at 80-90EF. Several combinations of bags and boxes have been tested in the system with volumes of 264-330 gallons. Bags tested were 3-ply (4 mil), ultra-low density polyethylene (ULDPE), with or without one of the plies being nylon-coated to retard oxygen transmission. Boxes tested included both rigid and collapsible types constructed of plastic, wood, synthetic fibers, or cardboard.

Brine composition. Brines (45% v) for fermented cucumbers were composed to equalize with cucumbers (55% v) at 0.32% acetic acid, 2 or 4% NaCl, 0.13% Ca(OH)2 and 0.13% CaCl2, and pH. 4.7. Brines for non-fermented cucumbers were composed as described by McFeeters in this symposium.

Culture. Cultures of Lactobacillus plantarum, grown fresh in our laboratory or provided commercially in dehydrated form, were added to the cover brine of cucumbers to be fermented at a concentration of about 1 million per mL of total volume of the bag.

Brine-stock quality. The firmness, bloater index, color, and flavor of fermented and non-fermented sizes 1 and 2 cucumbers were excellent. Bloater index and texture for size 3 cucumbers were acceptable but less favorable.

Fermentation end-products. Fermentation of cucumbers was complete within 1 month, and resulted in typical final concentrations of 0.96% lactic acid, 0.28% acetic acid, and 0.04% sugar, and pH 3.5.

Storage stability. Fermented cucumbers taken from the bags and stored in glass jars were microbiologically stable for up to 1 year when 4% salt was present, but stability was variable at 2% salt. The ULDPE bag allowed sufficient oxygen transmission to permit oxidative yeasts to grow at the brine/plastic interface within about 2 months. The nylon-coated ULDPE retarded but did not sufficiently restrict oxygen permeation. Alternative methods to solve this problem are being investigated.

Finished pickle products. Strategies were developed to utilize the entire bag contents of fermented cucumbers in finished pickle products. The brine was filtered to remove bacterial cells and used in partial acidification of the products. Products successfully prepared included sweet chips, hamburger dill chips, process dill whole pickles, and fresh-pack dill chips acidified with fermentation brine. These products were subjected to taste panel evaluation and received favorable ratings, compared to typical commercially available products.

Conclusions. The bag-in-box concept offers the potential for waste reduction/elimination and improved product quality and uniformity based on these studies, but some technical concerns should be addressed. Furthermore, economic feasibility of a commercial-scale operation must be considered.

For further information, contact:

  • Dr. H. P. Fleming, Professor
    • USDA-ARS, Department of Food Science
    • North Carolina State University, Raleigh, NC 27695-7624
    • Telephone: 919-515-2979; Fax: 919-856-4361
    • E-mail: hfleming@unity.ncsu.edu
  • Dr. E. G. Humphries, Professor Emeritus
    • Department of Biological and Agricultural Engineering
    • North Carolina State University, Raleigh, NC 27695-7625
    • Telephone: 919-515-6728; Fax: 919-515-7760
    • E-mail: humphrie@eos.ncsu.edu

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