Table 4b. Chemical analyses at red-ripe stage for pear tomatoes.

Treatment SSCz (°Brix) pH TTA (%) Sugar/acid ratio Initial (harvested at turning-breaker stage 3.7 cy 4.1 a 0.85 a 4.4 c Initial (harvested at red stage 4.9 a 4.2 a 0.65 b 7.5 b 5 °C/20 °C 4.4 ab 4.3 a 0.41 c 10.7 a 10 °C/20 °C 4.2 bc 4.1 a 0.67 b 6.4 bc 13 °C 3.8 c 4.1 a 0.53 bc 7.1 bc 20 °C 3.7 c 4.1 a 0.68 b 5.5 bc

zSSC = Soluble Solids Content; TTA = Total Titratable Acidity (citric acid equivalent). yColumns with different letters are significantly different at P < 0.5, according to Duncan’s Multiple Range Test.

Literature Cited Malundo, T. M. M., R. L. Shewfelt, and J. W. Scott. 1995. Flavor quality of fresh tomato (Lycopersicon esculentum Mill.) as affected by sugar and acid levels. Postharvest Biol. Technol. 6:103-110. Anonymous. 2002. Vegetable Acreage, Production, and Value; 2000-2001. Maul, F. 1999. Flavor of fresh market tomato (Lycopersicon esculentum Mill.) as in- Florida Agricultural Statistics Service. Orlando. http://www.nass.usda.gov/ fluenced by harvest maturity and storage temperature. Ph.D. Dissertation. fl/rtoc0ho.htm. Horticultural Sciences Department, University of Florida, Gainesville. 190 pp. Baldwin, E. A., J. W. Scott, M. A. Einstein, T. M. M. Malundo, B. T. Carr, R. L. Maul, F., S. A. Sargent, C. A. Sims, E. A. Baldwin, M. O. Balaban, and D. J. Hu- Shewfelt, and K. S. Tandon. 1998. Relationship between sensory and in- ber. 2000. Postharvest storage temperature affects tomato flavor and aro- strumental analysis for tomato flavor. J. Amer. Soc. Hort. Sci. 123:906-915. ma quality. J. Food Sci. 65:1228-1237. Chomchalow, S. 1999. Storage conditions and timing of ethylene treatment Moretti, C. L., S. A. Sargent, C. A. Sims, and R. Pushmann. 1997. Flavor alter- affect ripening uniformity and marketability of tomato fruits. M.S. Thesis. ation in tomato fruit due to internal bruising. Proc. Fla. State Hort. Soc. Horticultural Sciences Dept., University of Florida, Gainesville. 110:195-197. FAOSTAT. 2000. FAOSTAT Agricultural Data. Vegetable Production for Moretti, C. L., S. A. Sargent, D. J. Huber, and R. Puschmann. 1998. Chemical 1998. http://apps.fao.org/page/collections?subset = agriculture. composition and physical properties of pericarp, locule, and placental tissues Hardenburg, R. E., A. E. Watada, and C. Y. Wang. 1986. The Commercial of tomatoes with internal bruising. J. Amer. Soc. Hort. Sci. 123:656-660. Storage of Fruits, Vegetables, and Florist and Nursery Stocks. U.S. Dept. Sargent, S. A., A. J. Fox, F. Maul and R. C. Hochmuth. 1999. Postharvest qual- Agric. Agriculture Handbook 66. Washington, D.C. 136 pp. ity of greenhouse-grown tomatoes. Proc. Southeastern U.S. Greenhouse Kader, A. A., M. A. Stevens, M. Albright-Holton, L. L. Morris, and M. Algazi. Vegetable Growers Conf. May 19. pp. 35-46. 1977. Effect of fruit ripeness when picked on flavor and composition in U.S. Dept. of Agric. 1976. United States Standard for Grades of Fresh Market fresh market tomatoes. J. Amer. Soc. Hort. Sci. 102:724-731. Tomatoes. Agricultural Marketing Service, Washington, D.C.

Proc. Fla. State Hort. Soc. 115:84-86. 2002. CITRUS PEELING TECHNOLOGY FOR FLORIDA FRESH CITRUS

MOHAMED ISMAIL1 AND MARK THOMAS FDOC by Heinzen Manufacturing, Inc. (HMI) of Gilroy, Califor- Scientific Research Department nia. In 1999 a two-head peeling system capable of peeling 50 Florida Department of Citrus fruit per minute was built. Use of food grade pectinase enzyme 700 Experiment Station Road preparation facilitated the peeling process and was instrumen- tal to the success of the new peeling machine. The new peeling Lake Alfred, FL33850 unit has a 1 ft2 foot print and utilizes a number of blades to score the peel to a depth of approximately 2 mm. The rind is re- Additional index words. fresh-cut, convenience, consumption, moved using six spring-loaded members equipped with fixed automation barbs that impale and strip the peel off the fruit as it passes through the peeling unit. Several improvements have been in- Abstract. Changes in the life style in the U.S. and European so- corporated into the peeling unit since its introduction in 1999 cieties have resulted in increased demand for convenient, resulting in greater peeling efficiency and enhanced machine ready-to-eat and easy to prepare foods. This, along with de- durability. HMI is currently licensed to manufacture the peeling creased consumption of grapefruit prompted the Florida De- system and use of the technology is licensed to two compa- partment of Citrus (FDOC) to initiate a research program aimed nies. Marketing of fresh-cut citrus products by these compa- at enhancing fresh citrus fruit convenience. Development of an nies is expected to debut during the 2002-2003 citrus season. efficient peeling system for Florida oranges and grapefruit be- A U.S. patent was issued on April 16, 2002. came top priority of the Fresh Fruit Scientific Research Pro- gram. In 1998, a tabletop prototype peeler was built for the Increased demand for fresh-cut, ready-to-eat fruits and vegetables has made this category one of the fastest growing 1Corresponding author. segments in the food industry. Sales of fresh-cut produce in

84 Proc. Fla. State Hort. Soc. 115: 2002.

the U.S. reached $12 billion in 2000 (PMA, 2000). It has merous attempts were made to develop peeling machines for grown by more than 100% from $5 Billion in 1995 to $10.1 citrus. Among these are the following three examples. Billion in 1999 and sales are projected to reach $19 billion in 2003. 1. Polk (1942) developed and patented a machine designed Fresh-cut fruits are becoming increasingly visible in the to score and strip the peel off of citrus fruit. Fruit had to produce department of many supermarkets. Attractively be capped and oriented with the stem-end up, before it packaged watermelon, cantaloupe, honeydew melon and was thrusted through a scoring and stripping mechanism pineapple are at the top of the fresh-cut category (PMA, which removed the peel from top to bottom. 2000). The increase in consumption is attributed primarily to increased consumer demand for convenience. With the ex- 2. Del Ser Gonzalez (1991) patented a machine for peeling ception of small volume of largely imported orange and citrus fruit. The fruit had to be manually positioned and grapefruit sections packed in syrup and preservatives, fresh- the peel was scraped off as the fruit rotated. Peeling is ter- cut citrus presence in the market is negligible. In the 1960 minated when the color of the fruit flesh is detected. The and 1970’s, Florida was home to a large and viable citrus sec- ends are then removed. tioning industry, focused primarily on grapefruit. Almost 3.5 million boxes of grapefruit were sectioned and canned dur- 3. Foxcroft and Mansfield (1992) patented a citrus peeling ing the 1955-56 season (Wenzel et al., 1956). Increased labor machine designed to remove a plug of edible portions off cost and shortage of labor, however, have driven many plants of citrus fruit following removal of part of the top and out of business. bottom of fruit. Consumption of fresh grapefruit in the U.S. has been de- clining. In 1978-79 per capita consumption was estimated at It is not clear whether any of these machines had been 7.29 lbs. It decreased to 5.75 lb. in 1998-99, a 21% decline successfully used in a commercial citrus peeling operation. (Table 1). While consumption of other fruits had increased (USDA, 1999). Total Fresh grapefruit shipments have declined Florida Department of Citrus Development from 46.5 million cartons in 1990-91 seasons to 32 million car- of Citrus Peeling Machine tons in 1999-2000 seasons. Domestic grapefruit shipments alone declined from15.4 million cartons in 1999-2000 to In 1978 Dr. Joseph H. Bruemmer of the United States Cit- 13.14 million in 2001-2002 (Holford, 2002). In the meantime, rus and Subtropical Products Laboratory in Winter Haven, pear consumption was increased by 46%, strawberries by 94% Florida developed a process of peeling and sectioning citrus and oranges by 30% (Table 1). The decline in grapefruit con- fruit with the use of pectolytic enzymes (Bruemer et al., sumption is generally attributed to difficulty of peeling and 1978). The process was patented in 1981 (Bruemmer, 1981). eating and also to inconsistency of taste. Grapefruit was re- Evaluation of the enzyme infusion process developed by ported to be second only to pineapple fruit in difficulty of Breummer (1981,) led to the discovery that water infusion fa- preparation and eating (The Packer, 1997). cilitated peeling of citrus fruit by hand. This was followed by To enhance fresh grapefruit convenience and increase its the development and patenting of a nonenzymatic peeling consumption, we initiated in 1995 a project aimed at develop- method (Pao et al., 1996). Hand peeling of water infused ing commercially viable peeling methods for grapefruit. grapefruit under commercial conditions was found to be slow and tedious, compared to enzyme- infused fruit. Workers at the Pre-peeled Fruit, Inc. in Groveland, Florida indicated that History of Citrus Peeling Automation water infused fruit were much harder to peel and clean. It was also tiring to repetitively peel water infused for several hours Building machines to accomplish tedious and repetitive compared to enzyme infused fruit (pers. comm.). tasks has always been the goal of many men and women ever Development of a peeling machine for citrus was started since the inception of the industrial revolution. Today we en- in 1996 when we initiated separate meetings with representa- joy a large variety of inexpensive, prepared foods because of tives of three companies with proven history in food and inventions of automated bottling, canning and packaging ma- fresh-cut equipment manufacturing. Following extensive dis- chines that accomplish these tasks at a speed not previously cussions and evaluation, HMI of Gilroy, California was select- attained or imagined and with a high degree of precision. Nu- ed to build the first prototype peeler based on FDOC recommendations. A tabletop peeling unit was built. It con- sisted of pneumatically controlled piston which thrusts the Table 1. Per capita consumption of major fruits in the U.S. from 1978 to fruit through six circular blades and six barbs mounted on 1998. spring-loaded stainless-steel arms. Water infused, California Per capita consumption (Kg/person) navel oranges were tested, with mixed results. Some fruits were partly peeled, others were not peeled at all and some Commodity 1978-79 1998-99 % Change were severely damaged. Banana 9.18/20.2 12.99/28.6 41.5% In 1999, a two-head peeling (Fig. 1) system was subse- Grapes 1.40/3.1 3.31/7.3 136% quently built by HMI and delivered to the FDOC at Lake Al- Pears 1.04/2.3 1.53/3.4 46% fred. The machine was not successful in peeling water infused Strawberries 0.96/3.2 1.87/4.1 94% ‘Valencia’ oranges, however, it was much more effective in Grapefruit 3.31/7.3 2.61/5.7 -21% peeling enzyme-infused fruit, incubated for at least half an Orange 5.23/11.5 6.77/14.9 30% hour. In April 1999, a provisional patent application was filed with U.S. Patent and Trademark Office and an application for Source: Fruit and Tree Nuts Situation and Outlook/FTS-287/October a permanent patent was submitted in April 2000. On Apr. 16, 1999. Eco. Res. Ser., USDA.

Proc. Fla. State Hort. Soc. 115: 2002. 85

7. Remnants of the albedo are removed either manually or by subjecting fruit to a turbulent chilled water flume. This also results in reducing enzyme residue in the fruit. 8. Fruit is chilled to 40 °F before sectioning and packaging. 9. Fruit temperature must be maintained at 35-38 °F for qual- ity maintenance and maximum shelf life. Mechanical features of the FDOC Peeling Machine Each peeling unit is equipped with adjustable, program- mable logic controls and proximity sensors to control timing. Its compact design allows fruit to be scored and stripped of peel with a single stroke of the thruster. One of the most im- portant and significant features of the peeling machine is that orientation of fruit is not required, as is the case in most previ- ous inventions. This feature saves significant labor hours in Fig. 1. The 1999 citrus peeling machine equipped with two peeling heads, the peeling process and should result in reduced product cost. a hopper and conveyor. The machine peels fruit of different sizes ranging from count 80 oranges to count 36 grapefruit. Each peeling unit is capable of peeling 20-30 fruit per min. A peeling system consisting of 2002, patent number 6,371,014 titled “Fresh Commodity eight peeling units is expected to peel 160-240 fruit per min. Peeling System and Methods” was issued (Ismail, et al.). On Apr. 16, 2002, a Continuation-in-part patent application was Conclusion filed with the U.S. Patent and Trademark Office. The applica- tion included substantial changes in the design and construc- Automation of the peeling process for citrus fruit has tion of the peeling unit which have significantly increased its been achieved through development, construction and pat- efficiency and durability. enting of a simple, yet efficient citrus peeler. Each peeling unit has a small foot print and is capable of peeling 20-30 fruit per min. A multi-unit peeling system can achieve large vol- Enzyme Peeling System Features ume of peeled fruit in an 8-h shift. The manufacturing and marketing of the system, world-wide has been assigned to Hei- In order to ensure efficient production of wholesome nzen Manufacturing, Inc. Large scale production of fresh-cut fresh-cut citrus fruit, the following steps are recommended: citrus is expected to debut during the 2002-2003 season.

1. Fruit must be of good internal quality and free of cuts and Literature Cited bruises. Bruemmer, J. H., A. W. Griffin, and O. Onayemi. 1978. Sectionizing grape- fruit by enzyme digestion. Proc. Fla. State Hort. Soc. 91:112-114. 2. Fruit should be washed, thoroughly rinsed and sanitized. Bruemmer, J. H. 1981. Method for preparing citrus fruit with fresh fruit fla- vor and appearance. U.S. Patent No. 4,284,651. 3. An optional and very effective method of sanitation is to Del Ser Gonzales. 1992. Fruit peeling machine. U.S. Patent No. 5,133,250. dip fruit in heated water maintained at 176 °F for one Food and Agriculture Organization of the United Nations. 2000. World Fruit ° Production FAO Website http://apps.fao.org minute or 168 F for two min (Pao and Davis, 1999). Foxcroft, G. and C. R. Mansfield 1992. Peeler. U.S. Patent No.5,105,734. Holford, J. 2002. Florida Industry Shipment through June 30, 2002. Holford 4. Thorough perforation at multiple points to a depth of ap- & Associates, Inc. Vero Beach, FL. proximately 1 mm is necessary to allow effective infusion Ismail, M. A., S. Pao, M. Thomas, R. Groppe, and E. Davidson. 2002. Fresh commodity peeling system and method. U.S. Patent No. 6,371,014. with the enzyme solution. Pao, S. C., P. D. Petracek, and G. Eldon Brown. 1996. Nonenzymatic fruit peeling method. U.S. Patent No. 5,560,951. 5. Vacuum infusion of fruit is achieved by placing them in a Pao, S. and C. L. Davis. 1999. Enhancing microbiological safety of orange vacuum infusion chamber and lowering the pressure to juice by fruit immersion in hot water and chemical sanitizers. J. Food Pro- tection. 63:756-760. 27 in Hg Vac (91 Kpa) and maintaining fruit completely The Packer. 1997. Fresh Trend: A 1997 profile of the fresh produce consum- submerged for at least five minutes. When atmospheric er. Volume C111, No. 54. pressure is restored to the chamber, the enzyme solution PMA. 2000. Fresh-Cut Produce Industry Overview. Newark, Delaware, USA. enters the evacuated space in the fruit. USDA. 1962. Grapefruit Sections in Chemistry and Technology of Citrus, Cit- rus products and Byproducts. Agriculture Handbook 98:30-32. USDA. 1999. Fruit and tree nuts situation and outlook/FTS-287. 6. Infused fruit are held in either air or under water heated Wenzel, F. W., R. L. Huggart, E. L. Moore, J. W. Sites, E. J. Deszyck, R. W. Bar- to 100-120 °F to promote enzyme action and facilitate ma- ron, R. W. Olsen, A. H. Rouse, and C. D. Atkins. 1956. Quality of canned chine peeling. grapefruit sections from plots fertilized with varying amounts of potash. Proc. Fla. State Hort. Soc. 69:170-175.

86 Proc. Fla. State Hort. Soc. 115: 2002.