University of California

For Abstracts

Control of discoloration on fresh-cut sunchoke tubers

Tianbo Wang (College of Food Science and Engineering, Shan Dong Agricultural University, Tai’an 271018, China), Qungguo Wang (College of Food Science and Engineering, Shan Dong Agricultural University, Tai’an 271018, China), Francis Pupin (Mann Lab, Dept. Plant Sciences, University of California, Davis CA 95616) and Marita Cantwell (Mann Lab, Dept. Plant Sciences, University of California, Davis CA 95616)

Sunchokes (Helianthus tuberosus L.) are inulin accumulating tubers native to North America that are edible raw or cooked, and have good potential as a fresh-cut product. Sunchokes perform well as fresh-cut slices except for the development of a reddish discoloration on the cut surface. Dip treatments with ethanol (5%) provided effective control of discoloration. Untreated or ethanol-treated sliced tubers were stored in air at 0 degrees C and 5 degrees C, with best quality of untreated slices (visual, color values) maintained at 0 degrees C, but ethanol treatments retarded discoloration at both temperatures. Ethanol treatment suppressed respiration rates, and reduced wound-induced PAL activity and phenolic concentrations. Controlled atmospheres of 3% O2 with 6 or 12% CO2 at 5 degrees C were less effective than ethanol dips to retard discoloration, although high CO2 atmospheres also retarded PAL activity and synthesis of phenolics. Techniques tested for increasing endogenous ethanol concentrations included holding tubers in a nitrogen atmosphere for up to 12 days at 10 degrees C, and using a static system after nitrogen flushing to allow accumulation of CO2 (up to 20%). These treatments were only partially effective to control slice discoloration. Another approach to retard discoloration was using preprocessing treatments including hot water dips plus a delay at 20 degrees C before cutting, and curing treatments (storage at 20 degrees C for 7 and 14 days). These treatments were effective to reduce discoloration on the fresh-cut slices.

Effect of harvest time on post-cutting quality of fennel (Foeniculum vulgare Mill.)

Capotorto Imperatrice (Department of Science of Agriculture, Food and Environment, University of Foggia , Italy), Maria Luisa Amodio (Department of Science of Agriculture, Food and Environment, University of Foggia , Italy), Giancarlo Colelli (Department of Science of Agriculture, Food and Environment, University of Foggia , Italy)

The maturity stage is a critical factor for the final quality of a fresh-cut product. The aim of this study was to evaluate the effect of different harvest time (HT) on post-cutting quality of fresh-cut fennels. Fennels cv. Tiziano were harvested from HT-1 (immature stage) to HT-7 (overmature stage), with HT-3 as a commercial maturity stage. After harvest, fennels were trimmed and cut into slices. For every HT, three replicates of 10 slices, were analyzed for visual quality (score), colour (L*, a*, b*), pH, total soluble solids, titratable acidity, total phenols, antioxidant activity and vitamin C contents. In addition, other 10 splices for each replicate were stored for 4 days at 5 degrees C in air and evaluated sensorially for visual quality and colour of the cut surface. Harvest time did not significantly affect the visual quality and color parameters of fresh-cut fennel while differences were found in total soluble solids that were significantly lower at HT-1 and increased until the end of harvesting. Total phenols and vitamin C contents showed similar trends, with lower values at HT-1 respect to HTs 2, 3 and 4, and then starting to decrease after HT-5. Fresh-cut fennel stored in air at 5 degrees C turned brown with no significant differences in visual quality and color parameters between HTs. In conclusion harvesting fennel during the full maturity stage keep higher values of phenols and vitamin C with a good sugar content; harvest date did not influence the browning of the cut surface during storage at 5 degrees C.

Elucidating the Wound Signal Mechanism in Fresh-cut Produce: Scientific Implications and Opportunities for Practical Applications and Novel Technologies

Luis Cisneros-Zevallos (Texas A&M University, College Station, Texas, USA)

Here we elucidate for the first time the wounding signal mechanism in fresh-cut produce. When wounding takes place as part of the fresh-cut processing operation of fruits and vegetables, a series of responses are elicited by the wounding stress including accelerated metabolism, quality changes, shorter shelf-life, decrease in vitamin C and synthesis of secondary metabolites of nutraceutical importance. Here we identify the primary and secondary signals involved in the wound response using different plant species like lettuce and carrots. Overall, once wounding is applied in fresh-cut produce a redox imbalance takes place with reactive oxygen species (ROS) playing a major role as secondary signals. In this presentation we will show in detail the different signals involved and their mode of action, the role of calcium ions as well as NADPH oxidase as generator of superoxide radicals and their effects in secondary metabolism as well as quality changes. In addition, by elucidating the signaling mechanism we will revisit the status of the actual technologies being used by the fresh-cut industry in relation to processing operations and the technologies being used to control browning in fresh produce. Furthermore, we will propose alternative approaches either by modifying current technologies or proposing novel technologies to enhance the quality of fresh-cut produce and/or enhance their nutritional content.

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Enhancing the shelf life and sensory quality of fresh cut mangos

Panita Ngamchuachit (Chulalongkorn University, Thailand), Hanne K. Sivertsen (Food Science & Technol., UCDavis), Diane M. Barrett (Food Science & Technol., UCDavis) and Elizabeth J Mitcham (Plant Sciences, UCDavis

Mango cultivar and ripeness stage at the time of cutting influences the quality of fresh-cut mango. Fresh-cut ‘Kent’ and ‘Tommy Atkins’ mangos were prepared from mangos of different initial ripeness stages (45 N, 35 N, and 25 N). Instrumental and sensory quality was assessed during 9 days of storage at 5 degrees C. The sensory profile of fresh-cut ‘Kent’ mango was predominant in fruity aroma, and overall aroma intensity, whereas fresh-cut ‘Tommy Atkins’ had less aroma, but had greater edge sharpness, edge fibrousness, moist and glossy appearance and fibrous texture. Consumers found ‘Kent’ more desirable than ‘Tommy Atkins’. The initial ripeness stage of 35 N for ‘Kent’ mango and 25 N for ‘Tommy Atkins’ mango were optimal for fresh-cut mango in terms of handling, visual quality, and quality maintenance during storage, and were well received by consumers. The effects of CaCl2 and calcium lactate on maintaining textural and sensory quality of fresh-cut “Kent” and “Tommy Atkins” mangos were also investigated. Mango cubes were subjected to CaCl2 and calcium lactate concentrations (0 M, 0.068 M, 0.136 M, 0.204 M) and dip times (0, 1, 2.5, 5 min). Quality was analyzed during 9 d of storage at 5 degrees C. ‘Tommy Atkins’ mango cubes became more orange, but also had more browning than Kent mango cubes during storage at 5 degrees C. Firmness retention was greater with mangos cubes treated with CaCl2 and the retardation was greater at higher calcium concentrations. Treatment at 10 degrees C with 0.136 M CaCl2 for 2.5 min for Tommy Atkins mangos and 1 min for Kent mangos was effective in retaining firmness during storage at 5 degrees C and was not disliked by consumers.

Extending shelf-life of minimally processed pumpkin with a carrageenan-based coating

Joanna, C.L.Y (MARDI), Latifah, M.N (MARDI), Siti Aisyah, A (MARDI), Zaulia, O (MARDI), Nur Azlin, R (MARDI), Nur Syafini, G (MARDI), Syed Abas, S.A. (MARDI)., Hairiyah, M (MARDI), Habsah, M (MARDI), Zaipun, M.Z (MARDI) and Nurul Adibah, M (MARDI)

Effect of carrageenan coating at different concentrations on minimally processed pumpkin cubes was studied. Pumpkin cubes were subjected to a 3 min dipping into a solution containing carrageenan-based (0.1, 0.3 and 0.5 %, w/v) and glycerol (0-1%, w/v) coating. Samples (130 - 150 g) were sealed packed into polypropylene container (volume: 450 ml). Physical (weight loss, appearance and colour), chemical (pH, titratable acidity, soluble solids concentration and ascorbic acid content) and sensory evaluations were assessed during storage at 2 degrees C (70% relative humidity), 3 or 4 days interval for 3 weeks. Uncoated and coated minimally processed pumpkin cubes were subjected to steaming process (100 degrees C) for 5-7 min and were cooled prior to sensory evaluation. Significant weight loss (p< 0.05) was found in uncoated pumpkin cubes and tends to have a drier appearance after 10 days of storage. Higher concentrations of the coating (0.3 and 0.5%) causes jelly film to form over the surface of pumpkin cubes and was able to prevent moisture loss. Appearance of microbial spoilage started to form on uncoated surface pumpkin cubes after 17 days of storage. From the study, no significant differences was found for colour (L, a and b values), firmness and chemical) variables among treatments throughout the storage period. Coated pumpkin cubes of 0.1, 0.3 and 0.5% of carrageenan were found to retain its colour, better texture and noted positive sensory scores until the end of the storage period compared to uncoated pumpkin cubes. The results indicated carrageenan coating of 0.1% was the most effective as coating treatment in term of sensory quality and able to prolong shelf-life of minimally processed pumpkin cubes up to 20 days.

Fresh Cut Process and Facility Design

Rudi Groppe

The Fresh Cut Process Line design and equipment selection presentation provides an overview of a typical fresh cut process line. This presentation is geared to be an introductory lesson in process design with a focus on equipment selection to implement the process plan. We will discuss the application of design zones and how they relate to sanitary equipment design.  The presentation will drill into the typical unit operations that apply to a fresh cut process line and highlight the latest ideas in providing a state of the art process line.

Understanding where pathogens existing and how they migrate in a process facility is the underling goal of The Sanitary Plant Design presentation. This presentation focuses on the application of sanitary design guiding principles and how they relate to both equipment design and facility design.  This presentation is designed to provide a basic understanding of the different hygienic zones that are based on a low risk to high risk assessment.  The presentation will cover typical components of a fresh cut facility from floors, walls to ceilings. We will also review floor drain systems and waste removal systems and electrical distribution systems and basic sanitary methods of manufacturing.

Fresh-cut Fruit Processing

(Alessandro Turatti) (Turatti North America)

Production of fresh-cut fruit is on the rise because consumers are increasingly aware of the importance of healthy dietary habits while looking for convenient and easy meal preparation, requiring a shorter amount of time. At the same time we are also seeing a radical change in the food available for meals eaten outside the home, whether this be at work or in school. Many of these food items represent an innovative and more practical way of eating fruit and drinking juice. Examples include peeled and cut fruit products, raw juices and fresh smoothies which are now readily available in cafeterias or in vending machines.

A fresh-cut fruit is a product whose original state has been physically altered by washing, slicing and peeling, while retaining its fresh nature. Indeed, it is precisely because it is fresh – free of preservatives and unpasteurized – that minimally processed fruit can retain its content of natural antioxidants, vitamins, fiber and minerals.

Nevertheless, despite the potential, processors of these types of products are facing numerous challenges not commonly encountered during fresh-cut vegetable processing. While not insurmountable, these difficulties encountered with fresh-cut fruit, require an higher and brand new level of technical and operational complexity. Research and technology will be required to assist all the stakeholders in this segment of the fresh-cut market to offer more convenient, safe and nutritional products, while guaranteeing continuously improved sustainable solutions. Automation and Food Safety will be the main guideline to providing a new generation of fresh-cut fruit products.

Non-thermal plasma for controlling postharvest decay of ‘Shiranuhi’ mandarin hybrid

PARK, KYUNG-JIN(Citrus research institute, National institute of horticultural and herbal science, RDA, Jeju 697-943, KOREA)AN, HYUN-JOO(Citrus research institute, National institute of horticultural and herbal science, RDA, Jeju 697-943, KOREA)KIM, SANG-SUK(Citrus research institute, National institute of horticultural and herbal science, RDA, Jeju 697-943, KOREA)

‘Shiranuhi’ mandarin hybrid([C. uhshiu × C. simensis] × C. reticulata) was produced as late-ripening citrus variety in Korea. ‘Shiranuhi’ mandarin is usually stored in cold warehouse under 5~10 degrees after harvesting. But, the cold storage of fruits has the demerits such as economic costs and malfunction of cold system. Recently, non-thermal plasma is introduced to prevent postharvest decay of fruits and vegetables. In this case, plasma was generated by the electrode plates. ‘Shiranuhi’ mandarin was stored under non-thermal plasma condition on May 18th 2014. The room temperature was 10 degrees, and the humidity was 70%. Total soluble solid and acidity were not significantly different between non-treated (NT) group and non-thermal plasma treatment (NPT) group for 50 days. Postharvest decay, however was induced by P. digitatum(green mold) and P. italicum(blue mold), and the second infection were reduced on NPT group significantly. In the decay rate, 19% was on NT group and 11% was on NPT group after 50 days. But the stem-end protrusion rot was induced on NPT group. The over-exposure of ozone gas and ionized hydrogen was the cause of symptom. So the optimum condition of non-thermal plasma has to be established depending on the kind of fruits and the scale of cold warehouse. That is, non-thermal plasma treatment prevents the postharvest decay, and the fruit quality of ‘Shiranuhi’ mandarin is not affected by non-thermal plasma during storage. Therefore non-thermal plasma treatment is considered as the convenient alternative for the fruit and fresh-cut products storage.

Preparation and Handling Fresh-Cut Root Vegetables

Merete Edelenbos (University of Aarhus, Department of Food Science, Aarslev, Denmark)

Root vegetables are among the most important food crops consumed worldwide. Root vegetables include true roots and specialized tubers and hypocotyls with a subterranean habit. The value of fresh-cut produce lies in their convenience, freshness and health properties. High quality produce can only be obtained from raw materials with an also high quality. The initial quality is determined by the genetic background, climatic conditions, cultivation practices, soil type, maturity at harvest and time in storage. The first step in handling is to wash and polish roots and to screen, sort, and grade, to remove soil and defective roots. Produce is peeled in a rotation carborundum drum or by knives to remove the outer skin. In this process, aroma and health promoting compounds can be lost if concentrated in the periderm. Up to 30 percent of solids are lost with mechanical abrasion. Cutting has a derived effect on quality; increased respiration and moisture losses, transitional ethylene production, evaporation of volatile compounds, mixing of enzymes and substrates and formation of volatiles, phenolics, and other secondary metabolites. Quality is less affected by sharp than blunt knives. Washing after cutting will remove cell exudate and lower incidence of microorganisms. However, washing also dilutes the contents of sensory and health promoting compounds. In spin drying, juice and washing water is removed and that affects flavour and taste. Processing has no or little effect on texture but can enhance tissue browning. Produce will dry out and lose moisture and change flavour if not packaged in appropriate material, with suitable moisture- and gas-barrier properties.

Processing and Handling of Fresh-cut Tropical Fruits

Latifah Mohd Nor, MARDI (Malaysia)

Consumer demand for healthful and convenient food began to merge with advances in processing and handling of fresh-cut fruit industries. The needs for tropical fruits to be marketed in fresh-cut/ready to eat forms is greater as compared to the temperate fruits due to the large fruit size, high price particularly early in the season, risk in obtaining poor quality pulp, difficulty in peeling/cutting and weight problems during transportation. Fresh-cut processing allows cut pieces to be carefully examined right to the fruit center. Thus it can be use as tool for quarantine treatment to enhance market access. The disruption of tissues and cell integrity during fresh-cut processing often increases respiration rate, ethylene synthesis, enzymatic browning and development of physiological disorders, which associated with increases in rates of other biochemical reactions responsible for changes in colour, flavor, texture and nutritional quality (sugar, acid and vitamin contents). Not only that, the damaged plant tissues also provide a nourishing medium for microbial growth. In view of the above, Malaysian Agricultural Research and Development Institute (MARDI), had undertaken intensive research in developing suitable fresh-cut processing techniques to cater the needs both for local and export markets. Due to the inherent nature of the tropical fruits (especially the skin and size), suitable mechanization inputs had also been developed to facilitate and speed up the processing time. New approaches in evaluating suitable postharvest treatments, improve packing systems and storage requirements became a main focus in the research and development activities. Pre-treatments to reduce microbial spoilage, excessive tissue softening and tissue browning are needed for quality improvement of fresh-cut pineapple. Modified atmosphere packaging by using seal or shrink wrapping shown to be effective for retail packing system. Temperature abuse occur during distribution and display, and some microorganism of concern may grow under low temperatures and modified atmospheres. Because of these potential hazards, the microbiological quality and safety of the fresh-cut fruits is of great concern. An effective sanitation program and strict adherence to good personal and process hygiene need to be employed during handling and market distribution to ensure safe and quality products delivered to the consumers. The beneficial outputs of the new approaches were observed during commercial trials of the selected tropical fruits to Hong Kong (2008 and 2014), Singapore (2009), Dubai (2010), Perth (2011) and Sydney (2013).

Quality and Shelf Life of Enzymatically Peeled and Segmented Citrus Fruits in Japan

Hidemi Izumi (Kinki University), Yuji Nakata (Kinki University), Ayano Inoue (Kinki University), Yoshihiko Ozaki (Kinki University)

Several Japanese citrus fruits, Hassaku, Sweet spring, May pummelo, and Satsuma mandarin, were either peeled by vacuum infusion of a pectinase solution or by hand and then the sections separated by hand. The citrus segments were then submerged in a cellulase solution to eliminate segment membranes. There were no significant differences in the microflora, nutrient value (ascorbic acid and ß-carotene contents), physiology (respiration and ethylene production rates), and physicochemical properties (texture, juice leakage, color index, and pH) between enzyme-peeled and hand-peeled segments of Hassaku, Sweet spring, and May pummelo. When enzyme-peeled Satsuma mandarin segments were compared with segments chemically-peeled using HCl and NaOH solutions in preparation for a conventional canned product, no differences were found in quality, except that the microbial diversity was less in enzyme-peeled segments and the respiration rate was less in chemically-peeled segments. Enzyme-peeled citrus segments were preferable to hand- or chemically-peeled segments for visual appearance. Enzyme-peeled Satsuma mandarin segments were stored in three types of package films with different O2 permeability to estimate the shelf life in a modified atmosphere packaging (MAP) at 10 degrees C. The CO2 approached an equilibrium of 3%, 5%, and 8% in respective packages after 4 days of storage. Microbiological, nutritional, and physicochemical quality of the segments was maintained throughout 6 days of storage regardless of the film’s package, suggesting that the shelf life of enzymatically peeled Satsuma mandarin segments as a fresh-cut produce is 6 days in a MAP at 10 degrees C.

Quality of Waterjet and Blade Cut Romaine Lettuce

Marita Cantwell (Dept. Plant Sciences, UC Davis, Davis, CA 95616 USA), Anderson Adriano Martins Melo (Universidade Federal de Viçosa, Viçosa, Brasil), Gyunghoon Hong (Dept. Plant Sciences, UC Davis, Davis, CA 95616) and Susanne Klose (R&D, Chiquita Brands NA/Fresh Express, Salinas CA 93901 USA)

Cutting fresh-cut produce is usually accomplished by stainless steel knives. Waterjet cutting employs a very small stream of high pressure water, with the type of nozzle, conveyor speed and water pressure being the main factors determining the quality of the cut. Two tests were conducted cutting romaine lettuce by an Urschel Translicer 2500 on a pilot process line using new or used and reconditioned (e.g., 3x used and sharpened) blades and by a KMT pilot waterjet system using standard or food grade nozzles. Cut romaine showed whitening dehydration and discoloration defects. In both tests, cut romaine had only minor differences in cut surface defects between blade and waterjet cutting when packaged in a modified atmosphere. However, large differences due to cutting treatments were observed in cut romaine stored in bags without modified atmosphere at 2.5 degrees C. In Test#1, pieces had very high quality with no differences between cutting method until after 15 days at 2.5 degrees C, when waterjet cut pieces had higher visual quality with less discoloration than blade cut pieces. New knife blades produced less damage on the cut surfaces than used and reconditioned blades. The food grade nozzle was superior to the standard waterjet nozzle and was the most important waterjet cutting parameter. In Test#2, discoloration appeared by day 8 in bags with no modified atmosphere at 2.5 degrees C and there were clear differences between the blade cutting and waterjet cutting. Potentially, improved cutting technology could reduce the need for extreme package atmospheres and/or ensure higher product quality with package leakers.

Response of plant tissue to wounding

Mikal Saltveit (UC Davis)
We are all aware that fresh-cut produce is alive, with all its accompanying attributes, but we often fail to consider what happens to the injured tissue as it responds to being wounded. The response to wounding can be physical (dependent on the current physical make-up of the tissue), biochemical (dependent on the existing chemicals within the tissue), and/or physiological (dependent on the ability of the wounded and adjacent tissue to physiological respond). Plant tissues have evolved an impressive, but very limited number of physiological responses to naturally occurring injuries. These responses can be desirable (e.g., wound healing of harvested root crops), or undesirable (e.g., lignification of vascular tissue, browning of cut surfaces). While most injuries incurred during fresh-cut preparation mimic naturally occurring injuries (e.g., cuts and abrasions), a few are so extensive (e.g., producing ‘baby’ carrots, cubing melons) that they can overwhelm the tissues ability to properly deal with them and elicit unexpected responses. The physiological response to these injuries may be mediated through a number of intermediates (i.e., wound signals, PGRs like ethylene). Understanding the limitations of natural responses and how to modulate them can be used to produce a more desirable fresh-cut product.

Sensory and physico-chemical characteristics of minimally processed tubers from “early” potato crops as affected by anti-browning dipping treatment and cultivar

Anita Ierna ( IVALSA, CNR, Section of Catania), Alessandra Pellegrino ( IVALSA, CNR, Section of Catania) , Isabella Di Silvestro ( ISAFOM, CNR, Section of Catania), Marina Buccheri (IAA, CREA, Milan)

Potato production in several Mediterranean countries is focused on the “early ” crop type. Due to the lack of data in literature on the qualitative traits of minimally processed “early” potatoes, we studied the effects of 3 anti-browning dipping treatments (sterile deionized water - SW; 0.2 % sodium bisulphite -SB as is usually used in the fresh –cut potato industry; 2.5% ascorbic acid + 2.5% citric acid -AA+CA) on the physico-chemical and sensory characteristics of tubers from eight cultivars (Antea, Arinda, Ditta, Liseta, Marabel, Matador, Mondial and Spunta) widely grown in the Mediterranean basin. Slices were packaged in pouches (15 cm x 20 cm) of PAPE 85 µm of layer- film selected since it is commonly used in the minimally processed potato industry- under passive modified atmosphere, stored at 8 ±1 degrees C. Overall, potatoes dipped in AA+CA solution allowed to obtaining in comparison to sulphited potatoes a better minimally processed product due to higher citric acid content (4.3 vs 2.9 mg 100 g-1 DM), ascorbic acid content (21.5 vs 12.2 mg 100 g-1 FW), antioxidant activity (41 vs 14 DPPH % reduction) and sensory characteristics (less browing and off-odour, more firm texture) . The best performances were shown by Arinda, Matador and Spunta, whereas Antea and Ditta appeared not suitable for minimally processed potatoes. Liseta, Marabel and Mondial provided an acceptable product . These results highlighted how the cultivar choice is a key aspect determining the overall quality of the minimally processed “early” tubers.

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