Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
Food Science and Human Nutrition
Non Technical Summary
Nearly one-third of all food produced globally is lost or wasted, which accounts for approximately 1.3 billion tons per year. An estimated 15% of fish and seafood is wasted during processing, packaging, and distribution in North America and Oceania as a result of poor product quality. Thirty-one percent of fish and seafood losses in the United States occur at the consumer level, accounting for the highest estimated percentage of any commodity based on 2010 data. Thus, seafood of poor quality is the primary source of seafood waste once it reaches land.Seafood quality is not easily defined. Think of an instance where a fish has "gone bad". "Bad" seafood products are commonly associated with an unpleasant odor (or aroma) before cooking. Alternatively, seafood "freshness" is often used to describe a combination of pleasant sensory attributesFor example, a person smelling fresh mackerel might sense individual components of seaweed, cucumber, and pumpkin. Once "fresh" mackerel undergoes biochemical degradation, "freshness" decreases as product attributes are changed to aged seaweed, oxidized oil, trimethylamine, or ammonia.Therefore, to improve seafood quality, we must be able to identify specific seafood aromas that determine whether a seafood product is good or bad.Because foods are a mixture of organic and inorganic chemical compounds, we can separate and identify compounds using different extraction techniques and analytical chemistry instrumentation, like gas chromatography / mass spectrometry (GC/MS). What results from this analysis is a profile, or "aroma fingerprint", of chemical compounds unique to different types of seafood, whether raw or prepared. A number of researchers have been successful using this type of analysis to determine potential spoilage indicators for finfish, shrimp, oysters, and crabs as it relates to human sensory perception.By determining the volatile and semi-volatile organic compounds in Florida's shrimp, oysters, clams, and lobster by Headspace Solid-Phase Microextration (HS-SPME), multidimensional gas chromatography / mass spectrometry (MDGC/MS), and liquid chromatography / mass spectrometry (LC/MS), the individual identified aroma chemicals can be purchased or synthesized and used as standard reference aromas for quality assurance personnel training. By using the chemical name of the compounds identified from instrumental analysis as a descriptive attribute in a trained sensory panel, the definition of quality and/or seafood "freshness" becomes specific. Moreover, chemical names are assigned internationally by established nomenclature rules and could be used as global seafood quality descriptors. If a universal sensory lexicon is established, seafood imported to a domestic food company can rely on the quality assurance group's assessment that the product smells like trimethylamine and a foreign supplier will understand why the quality is considered poor or inadequate.Therefore, we hypothesize that volatile and semi-volatile aroma compounds in shrimp, oysters, clams, and lobster can be identified and used to develop a sensory lexicon based on chemical name which will then be used by the seafood industry to train quality assurance personnel to evaluate seafood quality objectively.
Animal Health Component
50%
Research Effort Categories
Basic
(N/A)
Applied
50%
Developmental
50%
Goals / Objectives
Objective 1: Identify chemical compounds by name found in raw and steamed shrimp, oysters, clams, and lobsters harvested from Florida waters and monitor changes during frozen storage.Solid-Phase Microextraction (SPME) is a method used to extract volatile aroma compounds from the headspace of a vial after equilibrium conditions between the sample and the headspace are met (Béné et al. 2001a). After 20 years of flavor analysis and thousands of peer-reviewed publications, headspace SPME has established itself as the most widely published extraction method for volatile organic compound analysis of foods.Semi-volatile compounds analyzed by UHPLC will be included as a part of the aroma fingerprinting that determines quality attributes. There are a number of aroma compounds found in seafood integral to flavor and quality that are considered semi-volatile. For example, geosmin is a compound directly related to muddy off-flavor and aroma and is responsible for the inferior flavor quality of many aquacultured finfish when compared to wild caught. Other semi-volatile compounds important to seafood quality include putracine, cadaverine, and indole, which are all difficult to extract by headspace solid phase microextraction (HS-SPME).Finally, Objective 1 will generate chemical data from raw and steamed shrimp, oysters, clams, lobster and evaluate changes in aroma during frozen storage after two, four, and over six months.Objective 2: Develop training procedures for industry using the aroma fingerprinting of raw and steamed Florida shrimp, oysters, clams, and lobster.Reliance on sensory experts in the seafood industry has been the tried and true methods to determine seafood quality, especially as it relates to the sensory techniques of the Food and Drug Administration, where instrumental correlations to sensory results are not currently used to measure seafood quality. Although sensory analysis alone is quite effective and efficient, resulting information obtained involves the potential for bias, panelist variability, and other consequences of subjective human data collection.Quantitative Flavor Profiling (QFP) is a modification of quantitative descriptive analysis (QDA). In QFP, only the essential flavor attributes of a product are studied, as opposed to QDA that profiles all sensory attributes of a product. QFP uses flavor descriptors and physical references to quantify compounds in a food product and is often correlated to instrumental analyses to validate results.
Project Methods
Sample AcquisitionTen kilograms each of fresh shrimp, oysters, clams, and lobsters from Florida will be purchased from a local seafood vendor every three months on four separate occasions, or as the harvest season allows for fresh seafood product acquisition. The seafood will be immediately transferred to large insulated coolers, buried in flake ice, and transported to the Aquatic Food Products Laboratory at the University of Florida. Seafood will be transferred to covered corrugated cardboard boxes in a -30°C walk-in freezer in the Aquatic Food Products Pilot Plant until repacking. Name of the local seafood market, country of origin, and date of purchase will be recorded.Fresh shrimp, oysters, clams and lobsters previously purchased will be removed from frozen storage, repacked in 100g increments, vacuum-sealed, and replaced in frozen storage at - 30°C within one hour. Vacuum-sealed sub samples will be removed from frozen storage, as needed for analysis, and defrosted in a laboratory refrigerator at 20°C.Sample Preparation for Volatile Aroma ExtractionApproximately 25g of either frozen shrimp, oysters, clams, or lobsters with equal amounts of salt (NaCl), by mass, will be placed into a 3.5 cup food processor, chopped/blended for approximately one minute until homogenized. Salt is often added to food samples intended for SPME extraction of foods with high moisture content by keeping emulsions from occurring and limiting microbiological growth. The seafood-salt mixture will be transferred to 40-mL amber glass solid-phase microextraction (SPME) vials, fitted with polypropylene caps and polytrifloroethylene / silicone septa. The SPME fiber assembly, when inserted and unsheathed in the vial for sampling, will be approximately 1 cm from the top of the seafood-salt mixture. SPME vial caps will then be wrapped with Parafilm to further seal the vial.SPME vials containing the seafood-salt mixture will be placed in a carbon fiber heating block designed for SPME sampling, beginning at 40°C. Studies will be conducted to determine the optimum time and temperature for SPME sampling. Optimal SPME sampling relies on equilibrium of volatile compounds in the headspace from the sample. In order to determine the optimal SPME extraction temperature, gas chromatography with flame ionization detection (FID) will be conducted until peak areas from increasing sampling temperatures plateau at their maximum.Volatile AnalysisThe PI's existing multidimensional gas chromatograph (MDGC) equipped with one injection port, two ovens, an FID, a single-quadrupole mass spectrometer (MS), and a Dean's switch will be used to analyze volatile compounds extracted from the seafood-salt mixture headspace by a divinylbenze / carboxen / polydimethylsiloxane (DVB/CAR/PDMS) SPME fiber. Results from the initial separation by FID are then "heart-cut" using software that programs the Dean's switch to activate and send selected compounds to a second GC oven through a separate capillary column and detection by MS. Analysis by MDGC-MS results in less background interference when comparing MS scans to a database, providing more robust similarity searching capabilities for MS fragmentation patterns. National Institute of Science and Technology (NIST) (Gaithersburg, MD) Mass Spectrometry Spectra Database versions 11, 11s, 14, 14s, and Flavor and Fragrance Natural and Synthetic Compounds GC/MS Library from Shimadzu (Columbia, MD) databases and select authentic standards will be used to identify volatile flavor compounds of shrimp, oysters, clams, and lobster analyzed by headspace SPME-MDGC/MS.Semi-volatile AnalysisA rapid Ultra High Perfomance Liquid Chromatography (UHPLC) method has previously been developed by co-PI Sarnoski to detect amino acids and biogenic amines in Tuna and Mahi-Mahi. The method should be easily modified to detect these compounds in shrimp, oysters, clams, and lobster. This method allows for the detection of 10 amino acids and the biogenic amines dimethylamine, putrescine, cadaverine, and histamine in less than 20 minutes. Briefly, the procedures of the method are as follows:Amines and amino acids are extracted by a modified method of Zhai et al. (2012) using 5% (w/v) trichloroacetic acid (TCA) and centrifugation. The amino acids and biogenic amines are used then derivatized with dansyl chloride for diode array detection. An Agilent 1290 series UHPLC system equipped with a Kinetex 1.3µm C18 100 ? UHPLC Column (50 x 2.1mm) (Phenomenex, Torrance, CA) will be used for analysis. Retention times and standard curves for dilutions of biogenic amines and amino acids standards will be used to identify and quantify the target compounds in the samples.Development of a Modified Quantitative Flavor Profiling (MQFP) MethodVolatile and semi-volatile organic compounds detected and identified by SPME-MDGC-MS and UHPLC will be purchased from various flavor chemical providers. Thousands of purified, food-grade flavor standards are available for purchase from companies such as Sigma-Aldrich.Headspace SPME-MDGC-MS analysis of pink shrimpshrimp, oysters, clams, and lobster will identify flavor compounds. In order to minimize convolution during sensory descriptive analysis training, the top ten most potent compounds will be acquired for initial training. The selected ten aroma compounds will be used as comparative standards and screened for panelist ability of sensory differentiation until five to ten useful compounds are identified for use in further training. The aforementioned five to ten aroma compounds and their standardized chemical names will act as the lexicon for shrimp, oyster, clam, and lobster quantitative descriptive sensory analysis using a modified quantitative flavor profiling (MQFP) method.Quantitative descriptive sensory analysis methods include the Flavor Profile Method, Texture Profile Method, Quantitative Descriptive Analysis (QDA®) Method, SpectrumTM Descriptive Analysis Method, Time-Intensity Descriptive Analysis, as well as several other established methods within the paradigm (Meilgaard, Civille and Carr 2016). In these methods, a group of 10-15 panelists are trained to identify and measure certain sensory attributes associated with the product they are evaluating. A panel moderator / leader provides samples of a food product to the group and asks them to identify unique sensory characteristics to establish a list of food product attributes that may be perceived by panelists during future analyses. Panelists are screened for their ability to detect and quantify sensory perceptions common to the group during training.A method of sensory analysis training that combines quantitative descriptive analysis (QDA), quantitative flavor profiling (QFP), and modern language learning techniques, will be developed in this objective. Some of the modifications of QDA and QFP methodology may involve the trainee wearing headphones equipped with a microphone where directions are given by the moderator through the headphones; recording sensory descriptors verbally produced by the trainee rather than writing or typing responses; automated aroma; providing visual cues by virtual reality to trainees as the aromas are delivered to assist with flavor compound language memorization; and that the training environment is highly portable or materials widely available so that training can be done in nearly any controlled environment across the globe.